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While wildlife tourism may impact the animals it targets, it plays a critical role in public education and conservation awareness. Understanding changes in animal behaviour in response to tourism activities can inform the trade-offs between negative impacts and socioeconomic benefits. There are public claims that cage-diving activities may condition white sharks, Carcharodon carcharias , to interact with boats, and may potentially increasing risk of shark bites. We tracked the fine-scale movements of 73 white sharks in relation to cage-diving boats using acoustic telemetry between 2018 and 2022 at Neptune Islands, Australia, to investigate associative behaviour and factors potentially influencing residency and time spent in proximity to the cage-diving boats. White sharks spent gradually less time near cage-diving boats throughout their residency at the tourism site. This behaviour was consistent across individuals, years, sexes and sizes. Sharks, however, resumed their natural behaviours (i.e. initial amount of time near the cage-diving boats) each time they returned to Neptune Islands, suggesting that the observed habituation (i.e. loss of response to the stimulus used to attract sharks) did not last for long periods. These trends support the lack of long-term learnt behaviour of white sharks increasingly interacting with boats. Our results indicate that current management strategies such as regulating the number of days the industry can operate at the site and the amount of food-based attractant used, and reducing the amount of bait consumed can limit associative behaviour between white sharks and boats, while enabling continued opportunities for white shark tourism. Understanding how wildlife associate with humans can help ensure that best practices are in place for both the targeted animals and the people involved, particularly in the case of threatened and potentially dangerous species. • Shark responses to food-based attractant and tourism boats were reduced within days. • Natural behaviour resumed each time sharks returned to the tourism site. • Reduction in time near boats was consistent across sharks, years, sexes and sizes. • Residency varied across individuals but not time, supporting no long-term effects. • Current management and limited consumption of baits prevents conditioned behaviour. [ABSTRACT FROM AUTHOR]

Jumping spiders display some of the richest visually mediated behaviours in nature. Vision is indeed the most important sensory modality in these spiders where motion detection and response to visual stimuli allow key behaviours such as hunting, escaping from predators and mating. These spiders have been used in various experiments demonstrating the existence of good associative learning and memory abilities, whose mechanism parallels that found in vertebrates. Here we focused on the habituation and dishabituation (H/DH) paradigm, indicating either a gradual decrease in responsiveness to repeated visual stimuli (H), or a recovery in response wherein the reaction towards a known stimulus is enhanced (DH). H is an elementary form of nonassociative learning and memory, which is expected to vary from individual to individual. The link between personality and H/DH has been shown in many vertebrates, but rarely in invertebrates. The jumping spider Menemerus semilimbatus was used in our study to address the question of whether boldness is related to H/DH. In our protocol, habituation was assessed by repeatedly presenting a visual stimulus on a screen to spiders tethered on a locomotor compensator. In the same individuals, boldness was assessed in a walking arena equipped with a shelter. We found that M. semilimbatus habituated and dishabituated to our visual stimulus and that they differed along a shy–bold axis. However, contrary to our expectations, boldness was not related to learning. In consideration of these results, we speculate that the nature (neutral value) of the stimulus might have played a role in making learning independent from boldness. • We tested boldness and visual habituation in the spider Menemerus semilimbatus. • Spiders showed consistent boldness type in four behavioural parameters. • They reduced their response to the stimulus due to habituation. • They increased rotational movement in response to the first dishabituation stimulus. • Boldness was not related to habituation or dishabituation. [ABSTRACT FROM AUTHOR]

Human–wildlife interactions are increasing globally due to human population growth and development. Wildlife often develop an increased tolerance of humans through the learning processes of habituation, but habituation of large predators can increase risks to humans. Aversive conditioning is a management strategy that operationalizes learning to reduce wildlife tolerance of humans and thereby improve human safety. However, developed landscapes may select for wildlife phenotypes that are resistant to learning via aversive conditioning. We investigated American alligators', Alligator mississippiensis , response to capture and release (an assumed aversive experience) in coastal resort communities as a model system for understanding wildlife learning in human-dominated landscapes. Our objectives were to investigate whether the degree of human disturbance in the landscape was associated with baseline alligator tolerance of humans or mediated alligators' learning ability. We quantified tolerance using flight initiation trials and estimated learning ability as the response to capture and release using a 'before–after control impact' experimental design. Baseline alligator tolerance did not vary with disturbance, nor did the degree of disturbance impact alligator learning. However, alligators in areas where capture and release occurred were 1.5 times more likely to flee from an approaching human after treatment relative to before. Alligators in control units exhibited similar tolerance to humans over time. Alligator tolerance was also influenced by ambient weather, with alligators least tolerant of humans in cool and cloudy conditions and most tolerant in warm conditions, likely reflecting physiological constraints of ectothermy. While human-dominated landscapes may promote high tolerance of humans through habituation, our findings indicate that high tolerance does not preclude future learning by crocodilians and collectively lend credibility to the use of repeated capture and release as a potential form of aversive conditioning for crocodilians. • We investigated alligators' response to capture–release in human-dominated landscapes. • We examined relations between human disturbance and baseline tolerance and learning. • Baseline tolerance did not vary with disturbance but was influenced by ambient weather. • Alligators were less tolerant of approaching humans after experiencing capture–release. • The degree of landscape level human disturbance did not impact alligator learning. [ABSTRACT FROM AUTHOR]

• This study examined stress responses during preparation and speech stages in adults. • Cognitive load and RTs were higher during speech compared to preparation stages. • Emotional salience induced a negativity bias and activated low-frequency EEG bands. • High-frequency EEG bands plateaued, suggesting cognitive habituation over time. • Despite rising arousal, participants managed stress effectively with increased HRV. This study examined behavioral, electrophysiological (EEG), and autonomic responses to stress during the preparation and speech stages of five discourses among 26 adults. Participants underwent an increasingly stressful job-interview based on a modified Trier Social Stress Test, receiving feedback from an evaluative board. Findings showed increased RTs, higher cardiovascular responses [Pulse Volume Amplitude (PVA), and Heart Rate Variability (HRV)] and generalized increases in EEG frequency bands (delta, theta, alpha, beta, gamma) during the speech compared to the preparation stage. The rising emotional salience of the discourses induced a negativity bias and extensive low-frequency band activation (delta and theta) across the scalp in response to emotional demands. High-frequency bands exhibited a plateau effect, indicating less cognitive involvement as the discourses progressed. In our opinion, a possible interpretation is that this effect could be due to habituation mechanisms or coping strategies. Autonomic results revealed significant variations in PVA, with higher levels during the first discourse preparation, indicating substantial cognitive effort. Despite increased emotional arousal, participants managed stress effectively, as evidenced by increased HRV during the speech stage. Overall, during progressively increasing ecological psychosocial stress, individuals displayed marked emotional reactions in terms of low-frequency bands and cardiovascular indices, particularly during the first speeches rather than the preparation stages of an interview. [ABSTRACT FROM AUTHOR]

Optimal escape theory predicts that prey balance the costs and benefits of fleeing. However, the use of prior experience in prey escape decisions has been overlooked. Indeed, when repeatedly exposed to a nonlethal yet threatening stimulus, prey may adjust their escape response by habituating, delaying escape when repeatedly exposed to that stimulus, or by becoming sensitized, escaping sooner. Here, we investigated intrinsic and extrinsic drivers of short-term variation in flight initiation distance (FID, distance at initiating escape) in response to repeated human approaches in incubating female common eiders, Somateria mollissima. We predicted habituation to repeated exposure to threatening but nonlethal stimuli, reflected in decreased FID. We also expected increased habituation in females with a high current reproductive value (older breeders, females in good condition or laying large clutches) or brood value (early breeders). Last, we investigated whether changes in FID varied with threat level (i.e. different adult or nest predation risk or breeding habitat). The magnitude of change in FID was small and varied among individuals, depending on individual traits (body condition, clutch size and phenology) and perceived threat (island-specific adult predation risk). Accordingly, females in poorer body condition, that laid larger clutches or laid earlier in the season were more prone to become sensitized over repeated approaches. Consistent with the risk allocation hypothesis predicting a dampening of antipredator responses under chronic risk exposure, females were less prone to become sensitized when nesting on islands with high adult predation risk. These results underline the ability of animals to make plastic state- and context-dependent adjustments of antipredator behaviour when repeatedly confronted with nonlethal stimuli. Nevertheless, given the limited magnitude of within-individual, short-term adjustment of FID compared to the among-individual variation in FID, questions remain concerning the efficacy of these antipredator responses in a context of rapidly changing predation regimes. • The use of prior experience in guiding prey escape decisions has been overlooked. • We repeatedly measured flight initiation distance of incubating common eiders. • Individuals differed in their response to repeated human approaches. • Birds in poor condition, laying early or with large clutches became more sensitized. • Females were less prone to being sensitized under high adult predation risk. [ABSTRACT FROM AUTHOR]

Animal behaviour changes as individuals mature and these changes may affect not only average behaviour, but also behavioural variability within and between individuals. This could apply to escape behaviour, as behavioural variability might be particularly advantageous in predator-prey interactions, and prey individuals can adhere to different escape strategies. It is not yet known, however, if behavioural variability (unpredictability) is marked early in life, if it arises with time and how stable it is throughout ontogeny. We analysed the escape behaviour of the steppe grasshopper, Chorthippus dorsatus , using burst experiments repeated multiple times across four life stages. We quantified three aspects of escape behaviour and analysed the data using a multivariate double-hierarchical generalized linear model. Interindividual differences in average behaviour increased across life stages, resulting in an increase in population level variability. Unpredictability, however, remained relatively stable both within and across individuals. About 1.7–4.6% of the total phenotypic variance was explained by individual differences in unpredictability. Further, 2–6.5% was explained by differences between bursts of observations, such that interindividual differences in unpredictability explained a maximum of 11% of the total variance in escape behaviour at a given time. Our results indicate a stability of the unpredictability level in grasshopper escape behaviour, and that intraindividual variance in unpredictability is low, but that the overall magnitude of individual differences in escape behaviour increases with age. • Escape strategies of grasshoppers are relatively constant throughout life. • Jumps shift from left-directed in early life to straighter paths in adulthood. • Differences between individuals increase with time. • Habituation reduces frequency of escape jumps but does not change jump properties. [ABSTRACT FROM AUTHOR]

Wheel running endows aversion to a paired flavor in laboratory rats, reflecting a form of Pavlovian conditioning, where the contingency between the flavor and running is crucial for the development of flavor aversion. This study investigates the impact of additional wheel running (extra running) opportunities on the development of flavor aversion based on the contingent flavor-running training. All rats had access to a target solution, followed by the opportunity to run on 5 out of 10 training days. The three groups of rats differed in treatment on the remaining 5 days: Unsignaled rats ran after consuming familiar tap water, while signaled rats ran after ingesting a solution of another flavor (a cover cue), and control rats drank tap water without running. The post-training choice test revealed that the unsignaled rats exhibited a weaker aversion for the target flavor compared to the control rats, indicating an attenuating effect of the extra running on running-based conditioned flavor aversion. This "degraded contingency effect" remained unchanged when the running was signaled by another flavor cue: the target flavor preference of the signaled rats was equivalent to that of the unsignaled rats. The failure to obtain any effect of the second flavor on the target aversion suggests that the degraded contingency effect demonstrated here is better explained by either habituation or the comparator mechanism, rather than cue competition. [ABSTRACT FROM AUTHOR]

Extinction of fear and avoidance is not permanent and can return following contextual changes (termed renewal). The aim of the current study was to investigate the renewal of avoidance, threat expectancy, and fear ratings in an online avoidance task administered during the COVID-19 pandemic. One-hundred and two participants completed a task consisting of habituation, threat conditioning, avoidance conditioning, extinction with response prevention, and renewal. Tests for renewal occurred either in the original conditioning context (ABA, n = 52) or the extinction context (ABB, n = 50). Images of a quiet and a busy street served as relevant contexts. Renewal was evident whereby the ABA group showed a significant increase in threat expectancy when tested in the conditioning context, which had not been extinguished. This effect was not found for avoidance or fear ratings, nor for the ABB group who underwent the renewal test in the extinction context. The current study demonstrated differential renewal of threat expectancy in an online contextual avoidance paradigm. [ABSTRACT FROM AUTHOR]

• Mice freely sample odors from ports in their home cages hundreds of times per day. • Sampling rate increases by an odor of magnitude in response to an unexpected odor. • Increased sampling lasts for 24 h following introduction of an unexpected odor. We have developed a behavioral paradigm to study volitional olfactory investigation in mice over several months. We placed odor ports in the wall of a standard cage that administer a neutral odorant stimulus when a mouse pokes its nose inside. Even though animals were fed and watered ad libitum , and sampling from the port elicited no outcome other than the delivery of an odor, mice readily sampled these stimuli hundreds of times per day. This self-paced olfactory investigation persisted for weeks with only modest habituation following the first day of exposure to a given set of odorants. If an unexpected odorant stimulus was administered at the port, the sampling rate increased transiently (in the first 20 min) by an order of magnitude and remained higher than baseline throughout the subsequent day, indicating learned implicit knowledge. Thus, this system may be used to study naturalistic olfactory learning over extended time scales outside of conventional task structures. [ABSTRACT FROM AUTHOR]

• Insomnia presented with delayed habituation or reduced cortical inhibition. • We applied ceiling theory to explain abnormal CNV changes. • We used CNV and EEG to explain the cortical inhibition and habituation in insomnia. Cognitive dysfunction with abnormal cortical inhibition and habituation has frequently been found in patients with insomnia. And the so-called contingent negative variation (CNV) and EEG power spectral density (FFT) may be the best choice to explore the underlining pathophysiology. We used polysomnography (PSG) to record such objective PSG parameters. The amplitudes, latencies, areas of different CNV components such as oCNV, iCNV and tCNV, PINV have been selected and analyzed. Behavioral data such as manual reaction time (RT) has been analyzed. Spectral analysis was performed with fast Fourier transformation (FFT) on all channels to make a spectral analyses of EEG datas. The A-latency located in CZ or PZ were statistically longer in insomnia group than control group, the iCNV-latency located in insomnia group were statistically shorter than control group. The iCNV-amplitude located in insomnia group was lower than control group. The oCNV-amplitude or the tCNV-amplitude located in insomnia group was higher than control group. The oCNV-square, tCNV-square, or PINV-square located in insomnia group were significant larger than control group. β1 or β2 activity distributed in bilateral hemisphere were significantly increased in insomnia group than control group with different distributions. Our study revealed varied attentional and information processing in insomnia patients. Above all, we made a hypothesis with ceiling theory: Frontal lobe play an important role in maintaining cognitive processing, which needs much more energy consumption and leads to decreased fast EEG activity in frontal cortex, which contributes to reduced cortical inhibition, represented as abnormal CNV. [ABSTRACT FROM AUTHOR]

Learning is a process that allows animals to develop adaptive behavioural responses to novel situations within an individual's lifetime. The simplest form of learning, habituation, acts a fundamental filter mechanism, which allows animals to ignore irrelevant recurring stimuli, thereby freeing up fitness-related resources, such as time and energy, as well as neural capacity. Although earlier studies have demonstrated that habituation occurs in a variety of taxa ranging from insects to mammals, our knowledge of this process in elasmobranchs is limited. Sharks and rays face an increasingly popular shark-diving industry, so it is important to understand how sharks respond to attractants used by tourism operators. Our study investigated whether sharks habituate to the smell of a potential food source, which has been proposed as a sustainable alternative to actively feeding sharks. We exposed 11 captive juvenile sharks individually to the smell of squid for 4 min, three times per day for 21 days in the absence of a food reward. We found declining responses to the stimulus within and across daily exposure sessions, indicating both short- and long-term habituation. Our findings suggest that sharks learn to avoid wasting time and energy on inaccessible food sources. Given the decreasing response observed in our study, the use of olfactory cues only may have limitations in its efficacy to attract sharks for tourism purposes. Habituation may act as a driver of optimal foraging strategies, enabling sharks to quickly abandon low-yielding foraging patches in search of more productive sites. • We tested whether sharks habituate to olfactory cues. • Shark response to olfactory cues decreased over time. • Sharks showed both short- and long-term habituation. • Habituation may help optimize foraging strategies in sharks. • Olfactory cues alone may not suffice for shark tourism purposes. [ABSTRACT FROM AUTHOR]

Predation risk is a major driver of the distribution of prey animals, which typically show strong responses to cues for predator presence. An unresolved question is whether naïve individuals respond to mimicked cues, and whether such cues can be used to deter prey. We investigated whether playback of wolf sounds induces fear responses in naïve ungulates in a human-dominated landscape from which wolves have been eradicated since 1879. We conducted a playback experiment in mixed-coniferous and broadleaved forest that harboured three cervid and one suid species. At 36 locations, we played wolf sounds, sounds of local sheep or no sounds, consecutively, in random order, and recorded visit rate and group size, using camera traps. Visit rates of cervids and wild boar showed a clear initial reduction to playback of both wolf and sheep sounds, but the type of response differed between sound, forest type and species. For naïve wild boar in particular, responses to predator cues depended on forest type. Effects on visit rate disappeared within 21 days. Group sizes in all the species were not affected by the sound treatment. Our findings suggest that the responses of naïve ungulates to wolf sound seem to be species specific, depend on forest type and wear off in time, indicating habituation. Before we can successfully deter ungulates using predator sound, we should further investigate how different forest types affect the perception of naïve ungulates to these sounds, as responses to predator sound may depend on habitat characteristics. • Risk effects of cervids and wild boar differed between sound cue and forest type. • Ungulates habituated to predator playback within 3 weeks. • Responses of naïve ungulates to predator cues may be context dependent. [ABSTRACT FROM AUTHOR]

• Regular meditation practice reportedly affects sensory information processing. • Meditators reporting non-dual awareness during practice showed superior sensorimotor gating, relative to those without. • Subjective differences in meditation experience may be associated with differential sensory processing characteristics. Startle modulation paradigms, namely habituation and prepulse inhibition (PPI), can offer insight into the brain's early information processing mechanisms that might be impacted by regular meditation practice. Habituation refers to decreasing response to a repeatedly-presented startle stimulus, reflecting its redundancy. PPI refers to response reduction when a startling stimulus "pulse" is preceded by a weaker sensory stimulus "prepulse" and provides an operational measure of sensorimotor gating. Here, we examined habituation and PPI of the acoustic startle response in regular meditators (n = 32), relative to meditation-naïve individuals (n = 36). Overall, there was no significant difference between meditators and non-meditators in habituation or PPI, but there was significantly greater PPI in meditators who self-reported being able to enter and sustain non-dual awareness during their meditation practice (n = 18) relative to those who could not (n = 14). Together, these findings suggest that subjective differences in meditation experience may be associated with differential sensory processing characteristics in meditators. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to test the effectiveness of olfactory repellents (ORE) as a mitigation measure to reduce ungulate-vehicle collisions (UVC). In the first phase, an extensive field survey was undertaken while employing the Before-After Control-Impact (BACI) study design. On the basis of ungulate mortality, 134 road sections were monitored on foot along both roadsides once a week. The monitoring lasted fourteen weeks per year in both 2021 (Before period) and 2022 (After period). In the after period, 2022, ORE were applied within the impact segments. The second phase consisted of data verification and statistical analysis. The data revealed a decrease in UVC of 68%. The confidence interval of this estimate suggested, however, a great deal of uncertainty about the true value. Therefore, the data were pooled, and the Bayesian inference was applied. On the level of moderate evidence, ORE decreased the number of UVC by at least 43% and at most 60%. We also observed that the ORE effect was more pronounced in the first seven weeks after installation than in the following seven weeks, suggesting ungulate habituation to ORE. We have therefore concluded that for a short period (ideally corresponding to UVC peaks) ORE could be considered an effective safety measure for secondary roads. • We applied BACI to test olfactory repellents for reducing ungulate-vehicle collisions. • A high efficiency was found for the first seven weeks after installation. • Habituation to the repellents was detected after seven weeks from installation. • The olfactory repellents should be applied during peak periods of ungulate-vehicle collisions. [ABSTRACT FROM AUTHOR]

• Our study utilized stereo-electroencephalogram to investigate the dynamic interaction between attentional control and habituation processes in the prefrontal cortex, providing insights into how these fundamental mechanisms synergize during cognitive tasks. • Two distinct neural pathways within the subregions of prefrontal cortex are identified – a bottom-up dominant pathway orchestrated by the IFG, facilitating habitual responses, and a top-down dominant pathway modulated by the OFC, enabling attentional control to override ingrained habits. • Through an information model, we unveil unique patterns of information flow within the subregions of prefrontal cortex, particularly during color-word congruent and incongruent conditions, contributing to a comprehensive understanding of attentional regulation mechanisms. Attentional control, guided by top-down processes, enables selective focus on pertinent information, while habituation, influenced by bottom-up factors and prior experiences, shapes cognitive responses by emphasizing stimulus relevance. These two fundamental processes collaborate to regulate cognitive behavior, with the prefrontal cortex and its subregions playing a pivotal role. Nevertheless, the intricate neural mechanisms underlying the interaction between attentional control and habituation are still a subject of ongoing exploration. To our knowledge, there is a dearth of comprehensive studies on the functional connectivity between subsystems within the prefrontal cortex during attentional control processes in both primates and humans. Utilizing stereo-electroencephalogram (SEEG) recordings during the Stroop task, we observed top-down dominance effects and corresponding connectivity patterns among the orbitofrontal cortex (OFC), the middle frontal gyrus (MFG), and the inferior frontal gyrus (IFG) during heightened attentional control. These findings highlighting the involvement of OFC in habituation through top-down attention. Our study unveils unique connectivity profiles, shedding light on the neural interplay between top-down and bottom-up attentional control processes, shaping goal-directed attention. [ABSTRACT FROM AUTHOR]

Humans and nonhuman animals respond to food diversity by increasing intake and appetitive behaviors, reflecting enhanced valuation for items presented in the context of variety. Previous work on food variety effects has posited two main explanatory mechanisms. Variety could slow habituation processes by decreasing exposure to a single food item or could elicit contrast effects in which comparisons between items impact relative valuation. This study used three flavors of sucrose rewards to investigate rats' responses to qualitative reward variety in different variety contexts: low (2 flavors) and high (3 flavors) conditions. Control sessions used only a single flavored pellet (no variety). Animals were tested in low (10 trials), moderate (20 trials) and high consumption (30 trials) sessions. A trial within each session was defined as completion of the operant response and acquisition of the reward pellet. Cues associated with flavors were used to examine predictability and between-trial ('micro') variety. Indicators of a variety effect were found including faster responding for rewards during the variety context compared to an initial control (no variety) context. This decrease in response latency continued to be observed for some measures in post-variety control contexts. The most robust statistical finding of variety effects was found using trial-by-trial analysis, with shorter response latencies obtained for trials with outcomes differing from the preceding trial compared to successive trials with identical outcomes. These results have implications for understanding how a general reward context like variety impacts behavior, and for informing clinical approaches focusing on motivation and eating disorders. [ABSTRACT FROM AUTHOR]

• Second-order deception involves alternating between truths and lies to mislead. • We examined the relation between elementary second-order lying, ignorance attributions, and EFs in middle childhood. • Older children are less likely to tell second-order lies despite their slightly better executive functioning skills. • Second-order ignorance and verbal working memory positively predicts second-order lying. • Habituation could account for a better ability to tell truths to deceive compared to telling lies to deceive. In highly competitive contexts, deceptive intentions might be transparent, so conveying only false information to the opponent can become a predictable strategy. In such situations, alternating between truths and lies (second-order lying behavior) represents a less foreseeable option. The current study investigated the development of 8- to 10-year-old children's elementary second-order deception in relation to their attribution of ignorance (first- and second-order ignorance) and executive functions (inhibitory control, shifting ability, and verbal working memory). An adapted version of the hide-and-seek paradigm was used to assess children's second-order lie-telling, in which children were asked to hide a coin in either of their hands. Unlike the standard paradigm, the opponent did not consistently look for the coin in the location indicated by the children, so children needed to switch between telling simple lies and truths (elementary second-order lies about the coin location) to successfully deceive the recipient. The results showed that older children were less likely to tell elementary second-order lies. However, across the sample, when children decided to lie, this ability was positively related to their second-order ignorance attribution and their verbal working memory. Moreover, we obtained preliminary evidence for the presence of a habituation effect in second-order lying, with children being more accurate and having less variability in their truthful-to-deceive responses (this being the more frequently elicited response) than when telling lies to deceive. Our findings could have implications for understanding the mechanisms underlying children's ability to alternate between truths and lies to deceive. [ABSTRACT FROM AUTHOR]

• Voxel-wise GLM analysis failed to capture fMRI signal variability. • ROI-based ICC analysis differentiated fMRI signal reliability between stimuli. • Stimuli with negative emotional valence are more reliable than positive valence ones. • Emotional valence more than stimulus habituation impacts fMRI signal reliability. The emotional domain is often impaired across many neurological diseases, for this reason it represents a relevant target of rehabilitation interventions. Functional changes in neural activity related to treatment can be assessed with functional MRI (fMRI) using emotion-generation tasks in longitudinal settings. Previous studies demonstrated that within-subject fMRI signal reliability can be affected by several factors such as repetition suppression, type of task and brain anatomy. However, the differential role of repetition suppression and emotional valence of the stimuli on the fMRI signal reliability and reproducibility during an emotion-generation task involving the vision of emotional pictures is yet to be determined. Sixty-two healthy subjects were enrolled and split into two groups: group A (21 subjects, test-retest reliability on same-day and with same-task-form), group B (30 subjects, test-retest reproducibility with 4-month-interval using two equivalent-parallel forms of the task). Test-retest reliability and reproducibility of fMRI responses and patterns were evaluated separately for positive and negative emotional valence conditions in both groups. The analyses were performed voxel-wise, using the general linear model (GLM), and via a region-of-interest (ROI)-based approach, by computing the intra-class correlation coefficient (ICC) on the obtained contrasts. The voxel-wise GLM test yielded no significant differences for both conditions in reliability and reproducibility analyses. As to the ROI-based approach, across all areas with significant main effects of the stimuli, the reliability, as measured with ICC, was poor (<0.4) for the positive condition and ranged from poor to excellent (0.4–0.75) for the negative condition. The ICC-based reproducibility analysis, related to the comparison of two different parallel forms, yielded similar results. The voxel-wise GLM analysis failed to capture the poor reliability of fMRI signal which was instead highlighted using the ROI-based ICC analysis. The latter showed higher signal reliability for negative valence stimuli with respect to positive ones. The implementation of two parallel forms allowed to exclude neural suppression as the predominant effect causing low signal reliability, which could be instead ascribed to the employment of different neural strategies to cope with emotional stimuli over time. This is an invaluable information for a better assessment of treatment and rehabilitation effects in longitudinal studies of emotional neural processing. [Display omitted] [ABSTRACT FROM AUTHOR]

This study was to examine the relationship between preexposure to salt and stress-responsive resistance to acid, bile salt, and heat in Cronobacter sakazakii , Salmonella enterica serovar Enteritidis, Bacillus cereus , and Staphylococcus aureus. Stationary phase-grown cultures of C. sakazakii , S. Enteritidis, B. cereus or St. aureus were subjected to elevated concentrations of salt (maximally 14.0%), and the cells of each bacterium were allowed to grow at 37 °C for consecutive 6 d. The 6-d habituated cells were then subjected to acid (pH 2.0), 10% bile salt, and heat (60 °C) stresses. C. sakazakii , S. Enteritidis, and St. aureus were more sensitive to acid after the habituation process than their stationary phase-grown counterparts. Although the 0.5% salt-habituated cells of B. cereus better survived at a subsequent acid challenge than did the nonhabituated cells of this bacterium, there were no significant (p < 0.05) differences in the Gompertz-derived growth kinetics between salt-habituated and nonhabituated cultures. Similarly, C. sakazakii and S. Enteritidis cells preexposed to salt was far more heat-sensitive, whereas the preexposure of B. cereus and St. aureus to 0.5 and 8.0% salt, respectively, resulted in their increased survival against heat as compared with their nonhabituated control. Nevertheless, the resultant growth parameters revealed that salt has no clear inducive effect on the acquisition of resistance responses to heterogeneous stresses. Overall, the habituation to different concentrations of salt may variably influence the ability of C. sakazakii , S. Enteritidis, B. cereus , and St. aureus to resist acid, bile salt, and heat stresses. • Habitation of salt altered the resistance of pathogens against subsequent stresses. • Cell elongation was observed for salt-habituated rod-shape bacteria. • Habituation to 0.5% salt cross-protected B. cereus against acid. • Habituation to 0.5% and 8% salt cross-protected B. cereus and St. aureus against heat. • Stress response of salt-habituated pathogens varied depending on pathogen type. [ABSTRACT FROM AUTHOR]

Abstract Despite prior extensive investigations of the interactions between the amygdala and prefrontal cortex, few studies have simultaneously considered activation and structural connectivity in this circuit, particularly as it pertains to adolescent socioemotional development. The current multi-modal study delineated the correspondence between uncinate fasciculus (UF) connectivity and amygdala habituation in a large adolescent sample that was drawn from a population-based sample. We then examined the influence of demographic variables (age, gender, and pubertal status) on the relation between UF connectivity and amygdala habituation. 106 participants (15–17 years) completed DTI and an fMRI emotional face processing task. Left UF fractional anisotropy was associated with left amygdala habituation to fearful faces, suggesting that increased structural connectivity of the UF may facilitate amygdala regulation. Pubertal status moderated this structure-function relation, such that the association was stronger in those who were less mature. Therefore, UF connectivity may be particularly important for emotion regulation during early puberty. This study is the first to link structural and functional limbic circuitry in a large adolescent sample with substantial representation of ethnic minority participants, providing a more comprehensive understanding of socioemotional development in an understudied population. Highlights • Left uncinate fasciculus fractional anisotropy related to left amygdala habituation. • Pubertal status moderated this relation, association was stronger in less mature. • Limbic connectivity may be important for emotion regulation in early puberty. [ABSTRACT FROM AUTHOR]

Highlights • Infants showed similar perception narrowing in face and speech domains. • Narrowing in face and speech were not correlated at 6 months. • Narrowing in face and speech were negatively correlated at 9 months. • Narrowing in face and speech were positively correlated at 12 months. Abstract Although prior research has established that perceptual narrowing reflects the influence of experience on the development of face and speech processing, it is unclear whether narrowing in the two domains is related. A within-participant design ( N = 72) was used to investigate discrimination of own- and other-race faces and native and non-native speech sounds in 3-, 6-, 9-, and 12-month-old infants. For face and speech discrimination, whereas 3-month-olds discriminated own-race faces and native speech sounds as well as other-race faces and non-native speech sounds, older infants discriminated only own-race faces and native speech sounds. Narrowing in face and narrowing in speech were not correlated at 6 months, negatively correlated at 9 months, and positively correlated at 12 months. The findings reveal dynamic developmental changes in the relation between modalities during the first year of life. [ABSTRACT FROM AUTHOR]

Highlights • An action that delivers an ingestible substance can become linked directly to postingestive sensations. • This linking accompanies chunking when the final action in the chunked series is consummatory. • A stimulus then evokes recall of the action and this evokes anticipation of the postingestive sensations. • This enables the rate of the action to be directly sensitive to the current motivational state. • It prevents the rate from being sensitive to either outcome devaluation or contingency degradation. Abstract In animal behavioral experiments, extended training causes instrumental actions that deliver ingestible substances to lose sensitivity to outcome devaluation and contingency degradation, and to gain direct sensitivity to the current motivational state. These features of habitual control have been attributed to a process that relies on stimulus-response (S-R) associations linking the context to instrumental actions and Pavlovian associations linking the same context to orally-sensed properties of substances attained there. This Pavlovian process was conceived based on the results of irrelevant incentive experiments, but it is not supported by the results of all such experiments. An alternative process is therefore proposed here. In this process, recall of the instrumental action is evoked by an S-R association, but the rate at which this action is then performed is controlled by anticipation of postingestive sensations that have frequently followed it. This anticipation relies on recall of an association linking the action directly to the postingestive sensations. This association is learned during the formation of a chunked action series that begins with the instrumental action and ends with a consummatory response. It enables a prediction of subjective value that is directly influenced by the current motivational state, but is not influenced by devaluation or non-contingent delivery of the substance that has produced the postingestive sensations. [ABSTRACT FROM AUTHOR]

Highlights • Repetitive non-nociceptive stimulation is known to decrease in nociceptive signaling. • The anti-nociceptive effect of repetitive stimulation is a form of generalized habituation. • Endocannabinoid signaling is required for generalized habituation. • This generalized habituation is remarkably persistent. Abstract Repetitive activation of non-nociceptive afferents is known to attenuate nociceptive signaling. However, the functional details of how this modulatory process operates are not understood and this has been a barrier in using such stimuli to effectively treat chronic pain. The present study tests the hypothesis that the ability of repeated non-nociceptive stimuli to reduce nociception is a form of generalized habituation from the non-nociceptive stimulus-response pathway to the nociceptive pathway. Habituation training, using non-nociceptive mechanosensory stimuli, did reduce responses to nociceptive thermal stimulation. This generalization of habituation to nociceptive stimuli required endocannabinoid-mediated neuromodulation, although disrupting of endocannabinoid signaling did not affect "direct" habituation of to the non-nociceptive stimulus. Surprisingly, the reduced response to nociceptive stimuli following habituation training was very long-lasting (3–8 days). This long-term habituation required endocannabinoid signaling during the training/acquisition phase, but endocannabinoids were not required for post-training retention phase. The implications of these results are that applying principles of habituation learning could potentially improve anti-nociceptive therapies utilizing repeated non-nociceptive stimulation such as transcutaneous nerve stimulation (TENS), spinal cord stimulation (SCS), or electro-acupuncture. [ABSTRACT FROM AUTHOR]

Highlights • Smaller caudal ACC specifically was associated with greater SCR across trials. • Smaller caudal and rostral ACC interacted with PTSD on SCR across trials. • Smaller caudal and rostral ACC interacted with PTSD on SCR over threat conditions. • Smaller caudal ACC appears to be associated with habituation delay. • Small ACC × PTSD interaction is linked to habituation delay and elevated arousal. Abstract Posttraumatic stress disorder (PTSD) is associated with fear response system dysregulation. Research has shown that the anterior cingulate cortex (ACC) may modulate the fear response and that individuals with PTSD have abnormalities in ACC structure and functioning. Our objective was to assess whether ACC volume moderates the relationship between PTSD and fear-potentiated psychophysiological response in a sample of Gulf War Veterans. 142 Veteran participants who were associated with a larger study associated with Gulf War Illness were exposed to no threat, ambiguous threat, and high threat conditions in a fear conditioned startle response paradigm and also provided MRI imaging data. PTSD was assessed using the Clinician Administered PTSD Scale (CAPS). Decreased caudal ACC volume predicted greater psychophysiological responses with a slower habituation of psychophysiological magnitudes across trials (p < 0.001). PTSD diagnosis interacted significantly with both caudal and rostral ACC volumes on psychophysiological response magnitudes, where participants with PTSD and smaller rostral and caudal ACC volumes had greater psychophysiological magnitudes across trials (p < 0.05 and p < 0.001, respectively) and threat conditions (p < 0.05 and p < 0.005). Our results suggest that ACC volume may moderate both threat sensitivity and threat response via impaired habituation in individuals who have been exposed to traumatic events. More research is needed to assess whether ACC size and these associated response patterns are due to neurological processes resulting from trauma exposure or if they are indicative of a premorbid risk for PTSD subsequent to trauma exposure. [ABSTRACT FROM AUTHOR]

Highlights • Zebrafish explored more the new object in comparison to the familiar object. • Zebrafish explored the object in the novel location in comparison to the familiar location. • Control and 5 μM MK-801-treated animals explored the familiar object in comparison to the new object. • MK-801-treated animals did not show a preference for the familiar or novel location. • Habituation alters cortisol and performance in object recognition and object location tasks. Abstract This study aims to establish a protocol for evaluating the object recognition memory and object location tasks in zebrafish. We evaluated novel the object recognition memory and analyzed the exploration time of the objects during training and testing. Zebrafish explored more the new object in comparison to the familiar object (61% of exploration time during test session). We also tested the object location task and measured the exploration time of each object in the familiar and novel object location. There was a preference to explore the object in the novel location (63% of exploration time during test session). The effect of the non-competitive NMDA receptor antagonist MK-801 was investigated on the object recognition and object location memory. Control (water only) and treated animals (5 μM MK-801) presented a significant preference in exploring the familiar object in comparison to the new object (66 and 68% of exploration time, respectively, during test session); however, 10 μM MK-801-treated animals did not show differences in the exploration time of the objects. In the object location task, the animals treated with the 5 or 10 μM MK-801 did not show a preference for the familiar or novel location whereas the control group had a higher preference in exploring the object in the familiar location (64% of exploration time during test session). Considering the different responses of the control group between original task and in the regimen treatment, we evaluated the impact of habituation on cortisol levels of animals in three different protocols: (1) habituated at the experiment apparatus for 3 days (C1 condition), (2) habituated at the experiment apparatus for 3 days plus treatment tank exposure at fourth day (C2 condition), (3) habituated at the treatment tank and experiment apparatus for 3 days and exposed to treatment tank again at fourth day (C3 condition). The results showed higher levels of cortisol in animals submitted to C2 and C3 conditions compared to animals submitted to C1. When introduced to an acute stressor during C1 condition, we observed an increase in the cortisol levels and an absence of preference for the objects in comparison to control group, which had a preference for novel object and novel location. Fluoxetine treatment induced a decrease in cortisol levels and an absence of preference for the objects in C2 and C3 conditions in comparison to control group, which had a preference for familiar object. However, fluoxetine treatment induced a preference to the novel location in C2 and C3 conditions in comparison to control group, which had a preference for familiar location. These results indicate that treatment tank exposure induced a different performance in object recognition and object location memory due to stress responses. Therefore, these tasks are prone to evaluate memory in physiological and pathological conditions, but its use is limited due to sensitivity to stress caused by manipulation. [ABSTRACT FROM AUTHOR]

Abstract Most neuroscience cognitive experiments involve repeated presentations of various stimuli across several minutes or a few hours. It has been observed that brain responses, even to the same stimulus, evolve over the course of the experiment. These changes in brain activation and connectivity are believed to be associated with learning and/or habituation. In this paper, we present two general approaches to modeling dynamic brain connectivity using electroencephalograms (EEGs) recorded across replicated trials in an experiment. The first approach is the Markovian regime-switching vector autoregressive model (MS-VAR) which treats EEGs as realizations of an underlying brain process that switches between different states both within a trial and across trials in the entire experiment. The second is the slowly evolutionary locally stationary process (SEv-LSP) which characterizes the observed EEGs as a mixture of oscillatory activities at various frequency bands. The SEv-LSP model captures the dynamic nature of the amplitudes of the band-oscillations and cross-correlations between them. The MS-VAR model is able to capture abrupt changes in the dynamics while the SEv-LSP directly gives interpretable results. Moreover, it is nonparametric and hence does not suffer from model misspecification. For both of these models, time-evolving connectivity metrics in the frequency domain are derived from the model parameters for both functional and effective connectivity. We illustrate these two models for estimating cross-trial connectivity in selective attention using EEG data from an oddball paradigm auditory experiment where the goal is to characterize the evolution of brain responses to target stimuli and to standard tones presented randomly throughout the entire experiment. The results suggest dynamic changes in connectivity patterns over trials with inter-subject variability. Highlights The goal of this paper is to develop statistical approaches to modeling dynamic brain connectivity in signals recorded across replicated trials in an experiment. • Under the Markovian regime-switching vector autoregressive model (MS-VAR) models, signals switch between different states both within a trial and across trials. • The second approach, slowly evolutionary locally stationary process, characterizes the observed EEGs as a mixture of oscillatory activities at various frequency bands. • The SEv-LSP model uses the Fourier waveforms as building blocks and captures the dynamic nature of the amplitudes and cross-correlations of the band-oscillations. • The MS-VAR' model captures abrupt changes but the SEv-LSP model directly gives interpretable results and does not suffer from model misspecification. [ABSTRACT FROM AUTHOR]

Children with autism spectrum disorder (ASD) exhibit difficulties processing and encoding sensory information in daily life. Cognitive response to environmental change in control individuals is naturally dynamic, meaning it habituates or reduces over time as one becomes accustomed to the deviance. The origin of atypical response to deviance in ASD may relate to differences in this dynamic habituation. The current study of 133 children and young adults with and without ASD examined classic electrophysiological responses (MMN and P3a), as well as temporal patterns of habituation (i.e., N1 and P3a change over time) in response to a passive auditory oddball task. Individuals with ASD showed an overall heightened sensitivity to change as exhibited by greater P3a amplitude to novel sounds. Moreover, youth with ASD showed dynamic ERP differences, including slower attenuation of the N1 response to infrequent tones and the P3a response to novel sounds. Dynamic ERP responses were related to parent ratings of auditory sensory-seeking behaviors, but not general cognition. As the first large-scale study to characterize temporal dynamics of auditory ERPs in ASD, our results provide compelling evidence that heightened response to auditory deviance in ASD is largely driven by early sensitivity and prolonged processing of auditory deviance. [ABSTRACT FROM AUTHOR]

Arid-zone birds trade-off dehydration and hyperthermia during hot weather, as they are dependent on evaporative cooling when air temperature approaches or exceeds body temperature. Water points in many arid ecosystems become surrounded by piospheres, exposing drinking birds to high radiant heat loads and exacerbating this trade-off. This challenge will be aggravated under climate warming. One possible mitigation approach is to reduce heat loads birds experience when seeking water. We experimentally shaded water points on farmland in the Kalahari. We used a Before–After Control–Impact design to assess the impact of artificial shade on species, visitation rates and visitation patterns of drinking birds. The number of species drinking was not affected by the introduction of shade, but overall visitation rates declined, despite a habituation period prior to data collection and increased use of shaded water points during the heat of the day. Of the ten most common species, one –the smallest species in the study - significantly increased and four significantly reduced visitation rates to experimentally shaded water points. Providing shade benefited few species overall, perhaps because of increased perceived predation risk. Future work should investigate the impacts of shader design in order to develop this method as a conservation tool. [ABSTRACT FROM AUTHOR]

Learning by observing others has been acknowledged as a powerful learning strategy. Whereas in several species observation of fear conditioning or other operational procedures can improve subsequent performance during actual learning, much less attention has been paid to observational learning of spatial discrimination tasks. To this end, we developed a set of procedures in which the spatial memory of adult rats, Rattus norvegicus , was tested in an eight-arm radial maze. Moreover, in view of controversial information concerning the incidence of mistakes made by demonstrators on the effectiveness of observational learning, our observer rats watched experienced or nontrained demonstrators. Food-deprived observers and demonstrators were initially habituated to the maze with all arms baited. Then observers were placed in a mesh cage positioned above the maze while a demonstrator rat was locating the spatial position of three baited arms. Rats observing conspecifics progressively learning the spatial discrimination improved subsequent performance compared to a control group watching an empty maze, but only if the configuration of baited arms presented during demonstration and testing matched. Therefore, rats integrated relevant spatial information during observation and used it efficiently when their spatial discrimination was tested in the maze. However, when the information was provided by trained demonstrators, making no mistakes and visiting only baited arms, observer rats failed to exhibit improved performance. Nevertheless, when given an initial habituation without food rewards, rats were subsequently able to benefit from observation of trained demonstrators thus showing that watching mistakes was not necessary for successful observational learning. Together, these findings indicate that rats can acquire spatial information via observation enabling more pertinent search strategies during testing and that for observation to be beneficial, what is observed must be sufficiently relevant or novel to complement existing knowledge (here initial habituation with or without rewards). [ABSTRACT FROM AUTHOR]

Huber and O'Reilly (2003) proposed that neural habituation exists to solve a temporal parsing problem, minimizing blending between one word and the next when words are visually presented in rapid succession. They developed a neural dynamics habituation model, explaining the finding that short duration primes produce positive priming whereas long duration primes produce negative repetition priming. The model contains three layers of processing, including a visual input layer, an orthographic layer, and a lexical-semantic layer. The predicted effect of prime duration depends both on this assumed representational hierarchy and the assumption that synaptic depression underlies habituation. The current study tested these assumptions by comparing different kinds of words (e.g., words versus non-words) and different kinds of word-word relations (e.g., associative versus repetition). For each experiment, the predictions of the original model were compared to an alternative model with different representational assumptions. Experiment 1 confirmed the prediction that non-words and inverted words require longer prime durations to eliminate positive repetition priming (i.e., a slower transition from positive to negative priming). Experiment 2 confirmed the prediction that associative priming increases and then decreases with increasing prime duration, but remains positive even with long duration primes. Experiment 3 replicated the effects of repetition and associative priming using a within-subjects design and combined these effects by examining target words that were expected to repeat (e.g., viewing the target word ‘BACK' after the prime phrase ‘back to'). These results support the originally assumed representational hierarchy and more generally the role of habituation in temporal parsing and priming. [ABSTRACT FROM AUTHOR]

• The ability to process expressive facial movements developed in the first year of life. • Nine-month-olds could perceive happy from facial movements. • Three-month-olds perceived lower-level visual properties in facial movements. • Experience shapes infants' ability to perceive emotions from facial movements. Perceiving facial expressions is an essential ability for infants. Although previous studies indicated that infants could perceive emotion from expressive facial movements, the developmental change of this ability remains largely unknown. To exclusively examine infants' processing of facial movements, we used point-light displays (PLDs) to present emotionally expressive facial movements. Specifically, we used a habituation and visual paired comparison (VPC) paradigm to investigate whether 3-, 6-, and 9-month-olds could discriminate between happy and fear PLDs after being habituated with a happy PLD (happy-habituation condition) or a fear PLD (fear-habituation condition). The 3-month-olds discriminated between the happy and fear PLDs in both the happy- and fear-habituation conditions. The 6- and 9-month-olds showed discrimination only in the happy-habituation condition but not in the fear-habituation condition. These results indicated a developmental change in processing expressive facial movements. Younger infants tended to process low-level motion signals regardless of the depicted emotions, and older infants tended to process expressions, which emerged in familiar facial expressions (e.g., happy). Additional analyses of individual difference and eye movement patterns supported this conclusion. In Experiment 2, we concluded that the findings of Experiment 1 were not due to a spontaneous preference for fear PLDs. Using inverted PLDs, Experiment 3 further suggested that 3-month-olds have already perceived PLDs as face-like stimuli. [ABSTRACT FROM AUTHOR]

• We studied habituation and novelty detection via EEG and fNIRS at 1, 5 & 18 months. • fNIRS and EEG responses were correlated for habituation (1&5 m) and novelty (5&18 m). • Findings represent the first converging longitudinal infant fNIRS and EEG responses. • Responses were associated across a wide age band despite using different stimuli. • Cross-modality correlations may be strongest at times of great developmental change. Habituation and novelty detection are two fundamental and widely studied neurocognitive processes. Whilst neural responses to repetitive and novel sensory input have been well-documented across a range of neuroimaging modalities, it is not yet fully understood how well these different modalities are able to describe consistent neural response patterns. This is particularly true for infants and young children, as different assessment modalities might show differential sensitivity to underlying neural processes across age. Thus far, many neurodevelopmental studies are limited in either sample size, longitudinal scope or breadth of measures employed, impeding investigations of how well common developmental trends can be captured via different methods. This study assessed habituation and novelty detection in N = 204 infants using EEG and fNIRS measured in two separate paradigms, but within the same study visit, at 1, 5 and 18 months of age in an infant cohort in rural Gambia. EEG was acquired during an auditory oddball paradigm during which infants were presented with Frequent, Infrequent and Trial Unique sounds. In the fNIRS paradigm, infants were familiarised to a sentence of infant-directed speech, novelty detection was assessed via a change in speaker. Indices for habituation and novelty detection were extracted for both EEG and NIRS We found evidence for weak to medium positive correlations between responses on the fNIRS and the EEG paradigms for indices of both habituation and novelty detection at most age points. Habituation indices correlated across modalities at 1 month and 5 months but not 18 months of age, and novelty responses were significantly correlated at 5 months and 18 months, but not at 1 month. Infants who showed robust habituation responses also showed robust novelty responses across both assessment modalities. This study is the first to examine concurrent correlations across two neuroimaging modalities across several longitudinal age points. Examining habituation and novelty detection, we show that despite the use of two different testing modalities, stimuli and timescale, it is possible to extract common neural metrics across a wide age range in infants. We suggest that these positive correlations might be strongest at times of greatest developmental change. [ABSTRACT FROM AUTHOR]

The present research examined whether happy and unhappy people perceived the value of Olympic medals (i.e., Gold, Silver, and Bronze) differently. We hypothesized that, compared to unhappy people, happy people would perceive greater value for silver and bronze medals in relation to a gold medal because happy people habitually savor even small things more than unhappy people. In support of our argument, happy relative to unhappy participants preferred more the total-medal method (i.e., counting all medals, regardless of color) over the gold-first method (i.e., counting only gold medals) for the Olympic medal ranking (Study 1). In addition, happy people believed that smaller numbers of silvers and bronzes would be equal to one gold in value than unhappy people (Studies 2 and 3). Moreover, the belief about the frequency-not-intensity principle of happiness mediated the effects of happiness on the perception of the value of medals (Study 3). [ABSTRACT FROM AUTHOR]

Sex differences are a well-known phenomenon in Alzheimer's disease (AD), with women having a higher risk for AD than men. Many AD mouse models display a similar sex-dependent pattern, with females showing earlier cognitive deficits and more severe neuropathology than males. However, whether those differences are relevant to human disease is unclear. Here we show that in AD mouse models that overexpress amyloid precursor protein (APP) under control of the prion protein promoter (PrP), female transgenic mice have higher APP expression than males, complicating interpretations of the role of sex-related factors in such models. By contrast, in a tTa:APPsi model, in which APP expression is driven by the tetracycline transactivator (tTa) from the CaMKIIα promoter, there are no sex-related differences in expression or processing of APP. In addition, the levels of Aβ dimers and tetramers, as well as Aβ peptide accumulation, are similar between sexes. Behavioral testing demonstrated that both male and female tTa:APPsi mice develop age-dependent deficits in spatial recognition memory and conditional freezing to context. These cognitive deficits were accompanied by habituation-associated hyperlocomotion and startle hyper-reactivity. Significant sex-related dimorphisms were observed, due to females showing earlier onsets of the deficits in conditioned freezing and hyperlocomotion. In addition, tTa:APPsi males but not females demonstrated a lack of novelty-induced activation. Both males and females showed atrophy of the dentate gyrus (DG) of the dorsal hippocampus, associated with widening of the pyramidal layer of the CA1 area in both sexes. Ventral DG was preserved. Sex-related differences were limited to the DG, with females showing more advanced degeneration than males. Collectively, our data show that the tTa:APPsi model is characterized by a lack of sex-related differences in APP expression, making this model useful in deciphering the mechanisms of sex differences in AD pathogenesis. Sex-related dimorphisms observed in this model under conditions of equal APP expression between sexes suggest a higher sensitivity of females to the effects of APP and/or Aβ production. [ABSTRACT FROM AUTHOR]

The cellular and molecular basis of long-term memory in vertebrates remains poorly understood. Knowledge regarding long-term memory has been impeded by the enormous complexity of the vertebrate brain, particularly the mammalian brain, as well as by the relative complexity of the behavioral alterations examined in most studies of long-term memory in vertebrates. Here, we demonstrate a long-term form of nonassociative learning—specifically, long-term habituation (LTH)—of a simple reflexive escape response, the C-start, in zebrafish larvae. The C-start is triggered by the activation of one of a pair of giant neurons in the zebrafish’s hindbrain, the Mauthner cells. We show that LTH of the C-start requires the activity of NMDA receptors and involves macromolecular synthesis. We further show that the long-term habituated reflex can by rapidly dishabituated by a brief tactile stimulus. Our results set the stage for rigorous, mechanistic investigations of the long-term memory for habituation of a reflexive behavioral response, one that is mediated by a relatively simple, neurobiologically tractable, neural circuit. Moreover, the demonstration of NMDAR and transcriptionally dependent LTH in a translucent vertebrate organism should facilitate the use of optical recording, and optogenetic manipulation, of neuronal activity to elucidate the cellular basis of a long-term vertebrate memory. [ABSTRACT FROM AUTHOR]

People have written about habituation, a process that leads to decreased responsiveness to a stimulus, as well as its counterpart, sensitization, or an increased responsiveness to a stimulus, for over 2000 years. And, while intensive research in the last century has led to well-supported generalizations about mechanisms of habituation, we have not developed a ‘natural history’ of habituation and tolerance that would help us predict, based on life history and natural history variation, how species will respond to humans and anthropogenic stimuli. The need for predictive models has never been greater. In this essay I will review generalizations about these learning processes and point out how a clear understanding of mechanism can be used to inform wildlife management and generate testable management interventions. I will also highlight unanswered questions about habituation and sensitization, and establish the groundwork for developing a natural history of habituation and tolerance. [ABSTRACT FROM AUTHOR]

Sensory specific satiety (SSS) describes the decline in pleasantness associated with a food as it is eaten relative to a food that has not been eaten (the 'eaten' and 'uneaten' foods, respectively). The prevailing view is that SSS is governed by habituation. Nevertheless, the extent to which SSS results solely from this 'low-level' process remains unclear. Three experiments were conducted to explore the hypothesis that 'top-down' cognitive activity affects the expression of SSS; specifically, we manipulated participants' expectations about whether or not they would have access to alternative test foods (uneaten foods) after consuming a test meal (eaten food). This manipulation was motivated by 'Commodity Theory,' which describes the relative increase in value of a commodity when it becomes unavailable. We tested the hypothesis that a decline in the pleasantness and desire to eat the eaten food is exaggerated when uneaten foods are unavailable to participants. None of our findings supported this proposition - we found no evidence that SSS is dependent on top-down processes associated with the availability of other uneaten test foods. [ABSTRACT FROM AUTHOR]

Personality differences are widespread throughout the animal kingdom and can have important ecological and evolutionary consequences. Despite a rapidly increasing body of literature, large (marine) vertebrates remain underrepresented in personality research. Given their unique life history traits (e.g. slow growth rate, slow reproduction rate, long life span) and their pivotal role in ecosystem processes, this is an important gap in our current knowledge. Here we investigated consistency and plasticity in movement behaviour of wild juvenile lemon sharks, Negaprion brevirostris , by repeatedly subjecting sharks to open field tests. First, we investigated the presence of interindividual differences in movement behaviour in a novel open field. Second, we investigated the effect of trial repetition on movement behaviour to understand whether movement in a novel open field reflects a reaction to novelty, or general activity. Third, we estimated individual differences in habituation/sensitization rates over trial repetition and studied how the habituation rate was predicted by the initial movement rate. We found consistent individual differences in movement behaviour during the open field tests. Sharks showed habituation in movement behaviour (i.e. decrease) over repeated trials indicating that the movement behaviour during the first trials is a reaction to novelty, and not general activity. Individuals, however, differed in their rate of habituation (i.e. plasticity) and this rate was negatively related to an individual's movement behaviour in the first open field trial. In addition to showing individual differences in consistency and plasticity in juvenile lemon sharks, our study emphasizes the importance of examining the validity of personality tests when adapting them to new species. [ABSTRACT FROM AUTHOR]

Attention is known to be crucial for learning and to regulate activity-dependent brain plasticity. Here we report the opposite scenario, with plasticity affecting the onset-driven automatic deployment of spatial attention. Specifically, we showed that attentional capture is subject to habituation, a fundamental form of plasticity consisting in a response decrement to repeated stimulations. Participants performed a visual discrimination task with focused attention, while being occasionally exposed to a distractor consisting of a high-luminance peripheral onset. With practice, short-term and long-term habituation of attentional capture emerged, making the visual-attention system fully immune to distraction. Furthermore, spontaneous recovery of attentional capture was found when the distractor was temporarily removed. Capture, however, once habituated was surprisingly resistant to spontaneous recovery, taking from several minutes to days to recover. The results suggest that the mechanisms subserving exogenous attentional orienting are subject to profound and enduring plastic changes based on previous experience, and that habituation can impact high-order cognitive functions. [ABSTRACT FROM AUTHOR]

Reflexes are often insuppressible, predictable, and susceptible to external control. In contrast, conscious thoughts have been regarded as whimsical, ‘offline,’ and shielded from external control. Recent advances suggest that conscious thoughts are more reflex-like and susceptible to external control than previously thought. In one paradigm, high-level conscious thoughts (subvocalizations) are triggered by external control, as a function of external stimuli and experimenter-induced action sets. It has been hypothesized that these conscious contents are activated involuntarily and in a reflex-like manner. If such is the case, then these activations should possess a well-known property of the reflex: habituation. Accordingly, we found that involuntary high-level cognitions (subvocalizations) habituated (i.e., were less likely to arise) after repeated stimulation. As in the case of the habituation of a reflex, this novel effect was stimulus-specific. We discuss the implications of this finding for theories about consciousness and about psychopathological phenomena involving undesired, involuntary cognitions. [ABSTRACT FROM AUTHOR]

Cerebral blood volume (CBV) fMRI with ultrasmall superparamagnetic iron oxide particles (USPIO) as a contrast agent was used to investigate olfactory processing in rats. fMRI data were acquired in sixteen 0.75-mm coronal slices covering the olfactory bulb (OB) and higher olfactory regions (HOR), including the anterior olfactory nucleus and piriform cortex. For each animal, multiple consecutive fMRI measurements were made during a 3-h experiment session, with each measurement consisting of a baseline period, an odorant stimulation period, and a recovery period. Two different stimulation paradigms with a stimulation period of 40 s or 80 s, respectively, were used to study olfactory processing. Odorant-induced CBV increases were robustly observed in the OB and HOR of each individual animal. Olfactory adaptation, which is characterized by an attenuation of responses to continuous exposure or repeated stimulations, has different characteristics in the OB and HOR. For adaptation to repeated stimuli, while it was observed in both the OB and HOR, CBV responses in the HOR were attenuated more significantly than responses in the OB. In contrast, within each continuous 40-s or 80-s odor exposure, CBV responses in the OB were stable and did not show adaptation, but the CBV responses in the HOR were state dependent, with no adaptation during initial exposures, but significant adaptation during following exposures. These results support previous reports that HOR plays a more significant role than OB in olfactory habituation. The technical approach presented in this study should enable more extensive fMRI studies of olfactory processing in rats. [ABSTRACT FROM AUTHOR]

Establishing the neurocircuitry involved in inhibiting fear is important for understanding and treating anxiety disorders. To date, extinction procedures have been predominately used to examine the inhibition of learned fear, where fear is reduced to a conditioned stimulus (CS) by presenting it in the absence of the unconditioned stimulus (US). However, learned fear can also be reduced by habituation procedures where the US is presented in the absence of the CS. Here we used expression of the activity marker c-Fos in rats to compare the recruitment of several forebrain structures following fear habituation and extinction. Following fear conditioning where a tone CS was paired with a loud noise US, fear was then reduced the following day by either presentation of the CS or US alone (i.e. CS extinction or US habituation, respectively). This extinction and habituation training recruited several common structures, including infralimbic cortex, basolateral amygdala, midline thalamus and medial hypothalamus (orexin neurons). Moreover, this overlap was shared when examining the neural correlates of the expression of habituation and extinction, with common recruitment of infralimbic cortex and midline thalamus. However, there were also important differences. Specifically, acquisition of habituation was associated with greater recruitment of prelimbic cortex whereas expression of habituation was associated with greater recruitment of paraventricular thalamus. There was also less recruitment of central amygdala for habituation compared to extinction in the retention phase. These findings indicate that largely overlapping neurocircuitries underlie habituation and fear extinction and imply common mechanisms for reducing fear across different inhibitory treatments. [ABSTRACT FROM AUTHOR]

Assessment of learning ability in nonhuman primate (NHP) models is sometimes requested by regulatory authorities. The double choice object discrimination task using a Wisconsin General Testing Apparatus (WGTA) approach is typically being applied. In this study, the WGTA approach was performed on 66 juvenile cynomolgus monkeys aged 8–9 months in the predose phase of juvenile toxicity assessment. In addition, reversal learning data of seven control animals/gender were obtained for the weeks 25 and 52 of dosing. Gender differences in the number of days required to pass the habituation, learning or reversal learning phases were statistically comparable, males and females may be combined for statistical analysis. At first instance, the habituation phase was passed on average after 6.4 days, and the learning test on average after 8.6 days with improvement to 2.0–2.6 days for habituation and 6.4–6.7 days for learning in weeks 52. Power analysis (α = 0.05, one-sided t- test) revealed a sample size of 8 and 41 to predict a 50% and 20% difference, respectively. In conclusion, examination for learning ability, but not for memory ability (during repeated testing) is feasible in juvenile NHPs using the WGTA approach. [ABSTRACT FROM AUTHOR]

Investigation of the eyeblink response of humans to auditory and tactile stimulation focused on the determinants of the so called incremental stimulus intensity effect. In Experiment 1, two groups of participants were exposed to 100 tones from 60 to 87-dB in intensity. In Group Incremental, the tones increased from 60- to 87-dB in 3-dB steps, whereas participants in Group Random received the same intensities in a pseudorandom order. The performance of the two groups was compared to Group Constant that received all 100 tones at 90-dB intensity and to a fourth group, named “Apparatus” that received no stimulation. In a subsequent testing block, the results indicated that there was less responding to a 90-dB tone in the Incremental than in the other three groups, which replicates the incremental stimulus intensity effect. The novel observation was that there was also significantly less responding in the Incremental than in the other three groups to an untrained tactile stimulus, suggesting that the differences between the conditions may have implicated differences in a more general sensitization, in addition to any differences in stimulus-specific habituation. Experiment 2 demonstrated that repetition of tones at a fixed intensity caused a decrease in responding to the tones, but also an increase in responding to a novel tactile stimulus, as compared to an untrained condition. These results are discussed in terms of the interpretation of the incremental stimulus intensity effect suggested by Davis and Wagner (1969) and the AESOP ( Wagner & Brandon, 1989 ) treatment of habituation and sensitization. [ABSTRACT FROM AUTHOR]

Social recognition is an integral component of behaviour that underlies many much larger behavioural suites. For example, monogamous pair bonding is relatively meaningless if an individual cannot recall with whom the bond was with. The prairie vole, Microtus ochrogaster , is a socially monogamous rodent, well known for its long-term pair bonds between males and females. Although previous work has shown that bonded males reliably spend more time with their pair-mate over an unfamiliar female, recent work has demonstrated that single male prairie voles do not discriminate between females. This discrepancy raises the important question: do paired males distinguish between nonmate females? We asked whether pair bonding alters the expression of social recognition in male voles by comparing social recognition of single and pair-bonded males using the habituation/dishabituation paradigm. We found that pair-bonded, but not single male prairie voles showed social recognition of (nonmate) females, suggesting a shift in cognitive behaviour after pair bond formation. This difference was not due to differences in motivation to engage in social exchanges, as males attempted to contact unfamiliar females at similar levels. Based on these data, we speculate that the stage of life (single or bonded) influences the relevance of attending to social information of same- and opposite-sex conspecifics. [ABSTRACT FROM AUTHOR]

Words with negative valence capture attention and this increase in attentional resources typically enhances perceptual processing. Recently, data using continuous flash suppression (CFS) appear to contradict this. In prior research when Chinese words were unconsciously presented in CFS and contrast was raised until the word was identified, RTs to identify words with negative valence were slower than RTs to words with neutral valence. This result might be limited to situations where a logographic writing system is used and could reflect a type of cognitive aftereffect where previewing the word causes habituation. Data ( N = 60) indicate that results generalize from a logographic (Chinese) to an orthographic writing system (English). In addition, when words were previewed in CFS RTs were slowed for words with negative valence relative to words with neutral valence and this was reversed when words were shown binocularly. Implications for theories of unconscious word processing and cognitive aftereffects are discussed. [ABSTRACT FROM AUTHOR]

Introduction Acute stress induces increases in plasma inflammatory mediators, which do not habituate to repeated stress. Inflammation is a risk factor for age-related illnesses, highlighting the need to understand factors controlling inflammation. No studies have examined changes in pro- and anti-inflammatory gene expression in response to repeated acute stress in humans. Methods RNA was isolated from peripheral blood before, 30 and 120 min after exposure of n = 32 healthy human participants to the Trier Social Stress Test (TSST) on two days. Gene expression of interleukin (IL)-6, IL-1β, nuclear factor (NF)-κB and IκB was measured repeatedly on both days. We further assessed leukocyte numbers, plasma IL-6, and salivary cortisol. Results Stress induced IL-6 ( F = 44.7; p < 0.001) and cortisol responses ( F = 18.6; p < 0.001). Cortisol responses habituated ( F = 5.1, p = 0.003), but IL-6 responses did not (n.s.). All genes increased in response to initial stress (IL-6: F = 3.8; p = 0.029; IL-1β: F = 7.1; p = 0.008; NF-κB: F = 5.1; p = 0.009; IκB: F = 4.7; p = 0.013) and showed habituation to repeated stress (IL-6: t = 2.3; p = 0.03; IL-1β: t = 3.9; p = 0.001; NF-κB: t = 2.1; p = 0.041; IκB: t = 3.1; p = 0.005). Day 1 responses of IL-1β and IκB were not explained by changes in leukocyte populations, but IL-6 and NF-κB, as well as most day 2 changes were not independent of leukocyte populations. Conclusions Stress response and habituation of pro- and anti-inflammatory gene expression as found here might indicate that even on an intracellular level, inflammatory responses to acute stress are adaptive in that they respond to initial, but habituate to repeated, similar stress. Future studies will need to test whether non-habituation is predictive of disease. [ABSTRACT FROM AUTHOR]

Marine non-consumptive wildlife-oriented tourism, whereby tourists observe and/or interact closely with animals, without purposely having a detrimental effect on them, has been growing globally in recent decades. Human-mediated feeding (provisioning) is widely used by tour operators to attract target species, facilitate viewing and interaction with tourists. Although potential effects of such provisioning on terrestrial fauna have been given moderate scientific research attention, equivalent research in the marine environment is limited. Effects of provisioning marine wildlife may include direct habituation, behavioural change, and/or dietary impacts among individuals and species. There may also be disruption to the species associated assemblage. It was found that the literature on the effects of non-consumptive wildlife tourism is fragmented and results from different areas and taxa are frequently contradictory. Most studies appeared to be of a few years duration, at most. This reflects the relative immaturity of the industry – many enterprises studied typically commenced within the 1990s. Studies (other than fish) tended to focus on a focal species with few addressing the wider implications for the associated assemblage. Supplementary feeding may also have impacts on the health and wellbeing of provisioned animals. It is concluded that such nature tourism is often not benign – focal species and their assemblage are often disrupted. We conclude that funding to better understand the impacts and thus address them is imperative. To supplement funding for the research and monitoring required, an additional charge could incorporated into the fee charged to those engaging in marine wildlife tourism. [ABSTRACT FROM AUTHOR]