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This study had two research objectives. The first was to examine age-related differences in the fluency of speech outputs, as prior research contains conflicting findings concerning whether older adults produce more disfluency than younger adults. The second was to examine cognitive individual differences, and their relationship with the production of disfluency. One hundred and fifty-four adults completed a story re-telling task, and a battery of cognitive measures. Results showed that younger adults produced more um’s and fewer repetitions. For individual differences, results showed that inhibition and set shifting were related to the production of repetitions, and inhibition and working memory were related to uh production. Our results provide clarification about mixed findings with respect age and disfluency production. The individual differences provide clarification on theoretical arguments for disfluent speech in aging (e.g. Inhibition Deficit Hypothesis), and also sheds light on the role of executive functions in models of language production. [ABSTRACT FROM AUTHOR]

Being able to represent and remember verbally-encoded information about spatial environments from different perspectives is important for numerous daily activities. The present study examined how frequently individuals spontaneously engage in visual mental imagery and verbal rehearsal strategies in memory recall of spatial descriptions, and whether using certain strategies is associated with better recall performance. Memory recall for route (person-centred) and survey (object-centred) spatial descriptions was examined in a sample of 105 neurotypical individuals, who also reported to what extent they used route- and survey-based mental imagery and verbal rehearsal strategies in each description. Results showed that participants favoured a path visualisation strategy to recall the route description and a map visualisation strategy to recall the survey description. Regression models further showed that employing both imagery and verbal strategies was associated with better recall for both route and survey descriptions, although imagery strategies held a higher predictive power. The present findings highlight the fact that the spontaneous use of internal strategies in the form of visual imagery and verbal rehearsal is ubiquitous when recalling spatial descriptions and a core part of efficient spatial memory functioning. [ABSTRACT FROM AUTHOR]

Autobiographical memory research has largely focused on effortful, generative retrieval processes, particularly in cognitive ageing literature. However, recent evidence has shown that autobiographical memories are often retrieved directly, without effortful retrieval processes. In the present study, we examined the retrieval characteristics and the phenomenological qualities of directly and generatively retrieved memories in younger and older adults. Participants recalled autobiographical memories in response to word-cues and reported whether each of their memories was retrieved directly (i.e., memory popped into mind) or generatively (i.e., they actively searched for it), and provided ratings for several retrieval and phenomenological characteristics. Overall, directly retrieved autobiographical memories were recalled faster and with less effort, were more recent, more frequently rehearsed, more vivid, and more positive in valence than generatively retrieved memories. Importantly, while younger adults recalled a higher number of generatively retrieved autobiographical memories than older adults, there were no age effects on the number of directly retrieved memories. We also established the parallel-form reliability of the word-cue method in eliciting autobiographical memories by comparing two sets of word-cues. The results provide novel insights on the dissociable effects of retrieval type and ageing on autobiographical memories. Theoretical and practical implications of these findings are discussed. [ABSTRACT FROM AUTHOR]

Although involuntary autobiographical memories (IAMs) and déjà vu have important shared characteristics, in this commentary, we focus on potential differences that may question the argument that two phenomena lie on a continuum. We propose that differences in their frequency and autonoetic consciousness could be explained by different types of cues and memory representations involved in experiencing IAMs and déjà vu. [ABSTRACT FROM AUTHOR]

Mental representations of space can be generated and communicated with respect to different reference frames and perspectives. The present study investigated the effects of age and individual differences in domain-general executive functions on people's ability to process spatial relations as expressed in language within different spatial reference frames (SRFs). Healthy adults aged between 18 and 85 completed a novel task involving self-, third-person-, object-, and environment-centered judgements of spatial relations between two objects, as well as standard tests of working memory, inhibition, and mental flexibility. A psychometric evaluation confirmed the test-retest reliability and the convergent and divergent validity of the new task. Results showed that the lifespan trajectories varied depending on the SRF. Processing from a self-centered perspective or an object-centered frame remained intact throughout the adult-lifespan. By contrast, spatial processing from a third-person-centered perspective or within an environment-centered frame declined in late adulthood. Mediation regression models showed that mental flexibility accounted for a significant part of the age-related variance in spatial processing across all allocentric SRFs. The age effects on environment-centered processing were also partially mediated by age-related changes in visuospatial working memory capacity. These findings suggest that at least partially distinct systems are involved in mentally representing space under different SRFs, which are differentially affected by typical aging. Our results also highlight that people's ability to process spatial relations across different SRFs depends on their capacity to employ domain-general effortful cognitive resources. [ABSTRACT FROM AUTHOR]

Exposure to early-life stress is associated with long-term alterations in brain and behavior, and may aggravate the outcome of neurological insults. This study aimed at investigating the possible interaction between maternal separation, a model of early stress, and subsequent neonatal hypoxia-ischemia on emotional behavior and markers of synaptic plasticity in hippocampus. Therefore, rat pups ( N = 60) were maternally separated for a prolonged (MS 180min) or a brief (MS 15min) period during the first six postnatal days, while a control group was left undisturbed. Hypoxia-ischemia was applied to a subgroup of each rearing condition on postnatal day 7. Emotional behavior was examined at three months of age and included assessments of anxiety (elevated plus maze), depression-like behavior (forced swimming) and spontaneous exploration (open field). Synaptic plasticity was evaluated based on BDNF and synaptophysin expression in CA3 and dentate gyrus hippocampal regions. We found that neonatal hypoxia-ischemia caused increased levels of anxiety, depression-like behavior and locomotor activity (ambulation). Higher anxiety levels were also seen in maternally separated rats (MS180min) compared to non-maternally separated rats, but prolonged maternal separation prior to HI did not potentiate the HI-associated effect. No differences among the three rearing conditions were found regarding depression-like behavior or ambulation. Immunohistochemical evaluation of synaptophysin revealed that both prolonged maternal separation (MS180min) and neonatal hypoxia-ischemia significantly reduced its expression in the CA3 and dentate gyrus. Decreases in synaptophysin expression in these areas were not exacerbated in rats that were maternally separated for a prolonged period prior to HI. Regarding BDNF expression, we found a significant decrease in immunoreactivity only in the hypoxic-ischemic rats that were subjected to the prolonged maternal separation paradigm. The above findings suggest that early-life stress prior to neonatal hypoxia-ischemia leads to significant alterations in synaptic plasticity of the dorsal hippocampus during adulthood, but does not exacerbate HI-related changes in emotional behavior. [ABSTRACT FROM AUTHOR]

Given the insular’s anatomic complexity and functional interconnectivity, acute lesions may result in varied clinical presentations, including autonomic, somatosensory, perceptual, motor, affective, and cognitive deficits. Although functional neuroimaging studies have demonstrated its role in executive functions, no clinical manifestations have been reported to date. We present the case of a woman with an acute left anterior insular infarction leading to executive (i.e., word and design fluency, mental flexibility, sustained attention, inhibitory control), but not language, visuoperceptual, or memory impairment. This case confirms the left anterior insula’s involvement in executive functioning and suggests that an infarction may result in executive impairment. [ABSTRACT FROM AUTHOR]

Animal studies suggest that maternal separation, a widely used paradigm to study the effects of early life adversity, exerts a profound and life-long impact on both brain and behavior. The aim of the current study was to investigate whether adverse early life experiences interact with neonatal hypoxia–ischemia, affecting the outcome of this neurological insult at both functional and structural levels during adulthood. Rat pups were separated from their mothers during postnatal days 1–6, for either a short (15 min) or prolonged (180 min) period, while another group was left undisturbed. On postnatal day 7, a subgroup from each of the three postnatal manipulations was exposed to a hypoxic–ischemic episode. Behavioral examination took place approximately at three months of age and included tests of learning and memory (Morris water maze, novel object and novel place recognition), as well as motor coordination (rota-rod). We found that both prolonged maternal separation and neonatal hypoxia–ischemia impaired the animals’ spatial learning and reference memory. Deficits in spatial but not visual recognition memory were detected only in hypoxic–ischemic rats. Interestingly, prolonged maternal separation prior to neonatal hypoxia–ischemia augmented the reference memory impairments. Histological analysis of infarct size, hippocampal area and thickness of corpus callosum did not reveal any exacerbation of damage in hypoxic–ischemic rats that were maternally separated for a prolonged period. These are the first data suggesting that an adverse postnatal environmental manipulation of just 6 days causes long-term effects on spatial learning and memory and may render the organism more vulnerable to a subsequent insult. [ABSTRACT FROM AUTHOR]

Self-knowledge is a type of personal semantic knowledge that concerns one's self-image and personal identity. It has most often been operationalized as the summary of one's personality traits ("I am a stubborn person"). Interestingly, recent studies have revealed that the neural correlates of self-knowledge can be dissociated from those of general semantic and episodic memory in young adults. However, studies of "dedifferentiation" or loss of distinctiveness of neural representations in ageing suggest that the neural correlates of self-knowledge might be less distinct from those of semantic and episodic memory in older adults. We investigated this question in an event-related potential (ERP) study with 28 young and 26 older adults while they categorised personality traits for their self-relevance (self-knowledge conditions), and their relevance to certain groups of people (general semantic condition). Participants then performed a recognition test for previously seen traits (episodic condition). The amplitude of the late positive component (LPC), associated with episodic recollection processes, differentiated the self-knowledge, general semantic, and episodic conditions in young adults, but not in older adults. However, in older adults, participants with higher composite episodic memory scores had more differentiated LPC amplitudes across experimental conditions. Moreover, consistent with the fact that age-related neural dedifferentiation may be material and region specific, in both age groups some differences between memory types were observed for the N400 component, associated with semantic processing. Taken together, these findings suggest that declarative memory subtypes are less distinct in ageing, but that the amount of differentiation varies with episodic memory function. [ABSTRACT FROM AUTHOR]

Flashbulb memories (FBMs) refer to vivid and long-lasting autobiographical memories for the circumstances in which people learned of a shocking and consequential public event. A cross-national study across eleven countries aimed to investigate FBM formation following the first COVID-19 case news in each country and test the effect of pandemic-related variables on FBM. Participants had detailed memories of the date and others present when they heard the news, and had partially detailed memories of the place, activity, and news source. China had the highest FBM specificity. All countries considered the COVID-19 emergency as highly significant at both the individual and global level. The Classification and Regression Tree Analysis revealed that FBM specificity might be influenced by participants' age, subjective severity (assessment of COVID-19 impact in each country and relative to others), residing in an area with stringent COVID-19 protection measures, and expecting the pandemic effects. Hierarchical regression models demonstrated that age and subjective severity negatively predicted FBM specificity, whereas sex, pandemic impact expectedness, and rehearsal showed positive associations in the total sample. Subjective severity negatively affected FBM specificity in Turkey, whereas pandemic impact expectedness positively influenced FBM specificity in China and negatively in Denmark. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic created a unique set of circumstances in which to investigate collective memory and future simulations of events reported during the onset of a potentially historic event. Between early April and late June 2020, we asked over 4,000 individuals from 15 countries across four continents to report on remarkable (a) national and (b) global events that (i) had happened since the first cases of COVID-19 were reported, and (ii) they expected to happen in the future. Whereas themes of infections, lockdown, and politics dominated global and national past events in most countries, themes of economy, a second wave, and lockdown dominated future events. The themes and phenomenological characteristics of the events differed based on contextual group factors. First, across all conditions, the event themes differed to a small yet significant degree depending on the severity of the pandemic and stringency of governmental response at the national level. Second, participants reported national events as less negative and more vivid than global events, and group differences in emotional valence were largest for future events. This research demonstrates that even during the early stages of the pandemic, themes relating to its onset and course were shared across many countries, thus providing preliminary evidence for the emergence of collective memories of this event as it was occurring. Current findings provide a profile of past and future collective events from the early stages of the ongoing pandemic, and factors accounting for the consistencies and differences in event representations across 15 countries are discussed. [ABSTRACT FROM AUTHOR]

In the absence of a pharmacological cure, finding the most sensitive early cognitive markers of Alzheimer's disease (AD) is becoming increasingly important. In this article we review evidence showing that brain mechanisms of spontaneous, but stimulus-dependent, cognition overlap with key hubs of the default mode network (DMN) that become compromised by amyloid pathology years before the clinical symptoms of AD. This leads to the formulation of a novel hypothesis which predicts that spontaneous, but stimulus-dependent, conscious retrieval processes, that are generally intact in healthy aging, will be particularly compromised in people at the earliest stages of AD. Initial evidence for this hypothesis is presented across diverse experimental paradigms (e.g., prospective memory, mind-wandering), and new avenues for research in this area are outlined. The DMN was originally assumed to be involved in internally generated spontaneous thoughts owing to the high level of activity during 'rest'. Recent fMRI findings indicate that the DMN, and most notably the posterior cingulate cortex (PCC), are involved in the manifestation of spontaneous cognitions triggered by stimuli in the environment. Years before the diagnosis, AD-related amyloid accumulation appears to compromise key hubs of the DMN, especially the PCC, that are associated with spontaneous stimulus-driven cognitive phenomena. The spontaneous retrieval deficit hypothesis posits that patients with amnestic mild cognitive impairment (aMCI) and AD should demonstrate significant disruptions in bottom-up, cue-driven spontaneous cognitive processes. Evidence across prospective memory and mind-wandering studies supports this hypothesis. Tasks assessing spontaneous, but stimulus-dependent, conscious retrieval processes may be a good diagnostic means to detect the early stages of AD. [ABSTRACT FROM AUTHOR]