Search

Glossolalia is defined as the ritual oral production of phoneme sequences without recognizable semantic content. The functional underpinnings of glossolalia, and notably whether it consists of a highly specific or ordinary behavior, remain largely unresolved. We addressed this question by measuring the structural brain remodeling associated with the extensive practice of glossolalia in thirty experts. This approach enabled us to circumvent the limitations of functional imaging to reveal the neural correlates of behaviors elicited in specific contexts and involving movements incompatible with most imaging methods. Whole-brain regression analyses of glossolalia expertise with indices of grey and white matter structure revealed positive associations between practice time and grey matter volume within the left frontal pole and the right middle frontal gyrus. These findings suggest that glossolalia involves a degree of neurocognitive specialization, though not at the level of language control and production networks, but within domain-general executive areas. They further call for including multi-tasking and interference suppression as key processes in models of unrecognizable speech production. Our results also concur with current demonstrations that measures of brain structural remodeling may help identifying whether cognitive skills depend on networks specialization or on a recycling of already existing processes.

While declines in inhibitory control, the capacity to suppress unwanted neurocognitive processes, represent a hallmark of healthy aging, whether this function is susceptible to training-induced plasticity in older populations remains largely unresolved. We addressed this question with a randomized controlled trial investigating the changes in behavior and electrical neuroimaging activity induced by a 3-week adaptive gamified Go/NoGo inhibitory control training (ICT). Performance improvements were accompanied by the development of more impulsive response strategies, but did not generalize to impulsivity traits nor quality of life. As compared with a 2-back working-memory training, the ICT in the older adults resulted in a purely quantitative reduction in the strength of the activity in a medial and ventrolateral prefrontal network over the 400 ms P3 inhibition-related event-related potentials component. However, as compared with young adults, the ICT induced distinct configurational modifications in older adults’ 200 ms N2 conflict monitoring medial–frontal functional network. Hence, while older populations show preserved capacities for training-induced plasticity in executive control, aging interacts with the underlying plastic brain mechanisms. Training improves the efficiency of the inhibition process in older adults, but its effects differ from those in young adults at the level of the coping with inhibition demands.

Recent lines of research suggest that repeated executive control of motor responses to food items modifies their perceived value and in turn their consumption. Cognitive interventions involving the practice of motor control and attentional tasks have thus been advanced as potential approach to improve eating habits. Yet, their efficacy remains debated, notably due to a lack of proper control for the effects of expectations. We examined whether a one-month intervention combining the practice of Go/NoGo and Cue approach training modified the perceived palatability of food items (i.e. decrease in unhealthy and increase in healthy food items' palatability ratings), and in turn participants’ weights. We assessed our hypotheses with a parallel, double-blind, randomized controlled trial. Motivation and adherence to the intervention were maximized by a professional-level gamification of the training tasks. The control intervention differed from the experimental intervention only in the biasing of the stimulus–response mapping rules, enabling to balance expectations between the two groups and thus to conclude on the causal influence of motoric control on items valuation. We found a larger decrease of the unhealthy items' palatability ratings in the experimental (20.6%) than control group (13.1%). However, we did not find any increase of the healthy items’ ratings or weight loss. Overall, the present registered report confirms that the repeated inhibition of motor responses to food cues, together with the development of attentional biases away from these cues, reduces their perceived value.

While the deleterious effects of acute ethyl alcohol intoxication on executive control are well-established, the underlying spatiotemporal brain mechanisms remain largely unresolved. In addition, since the effects of alcohol are noticeable to participants, isolating the effects of the substance from those related to expectations represents a major challenge. We addressed these issues using a double-blind, randomized, parallel, placebo-controlled experimental design comparing the behavioral and electrical neuroimaging acute effects of 0.6 vs 0.02 ​g/kg alcohol intake recorded in 65 healthy adults during an inhibitory control Go/NoGo task. Topographic ERP analyses of covariance with self-reported dose expectations allowed to dissociate their neurophysiological effects from those of the substance.While alcohol intoxication increased response time variability and post-error slowing, bayesian analyses indicated that it did not modify commission error rates. Functionally, alcohol induced topographic ERP modulations over the periods of the stimulus-locked N2 and P3 components, arising from pre-supplementary motor and anterior cingulate areas. In contrast, alcohol decreased the strength of the response-locked anterior cingulate error-related component but not its topography. This pattern indicates that alcohol had a locally specific influence within the executive control network, but disrupted performance monitoring processes via global strength-based mechanisms.We further revealed that alcohol-related expectations induced temporally specific functional modulations of the early N2 stimulus-locked medio-lateral prefrontal activity, a processing phase preceding those influenced by the actual alcohol intake.Our collective findings thus not only reveal the mechanisms underlying alcohol-induced impairments in impulse control and error processing, but also dissociate substance- from expectations- related functional effects.

While cognitive interventions aiming at reinforcing intentional executive control of unwanted response showed only modest effects on impulse control disorders, the establishment of fast automatic, stimulus-driven inhibition of responses to specific events with implementation intention self-regulation strategies has proven to be an effective remediation approach. However, the neurocognitive mechanisms underlying implementation intentions remain largely unresolved. We addressed this question by comparing electrical neuroimaging analyses of event-related potentials recorded during a Go/NoGo task between groups of healthy participants receiving either standard or implementation intentions instructions on the inhibition stimuli. Inhibition performance improvements with implementation intentions were associated with a Group by Stimulus interaction 200–250 ms post-stimulus onset driven by a selective decrease in response to the inhibition stimuli within the left superior temporal gyrus, the right precuneus and the right temporo-parietal junction. We further observed that the implementation intentions group showed already at the beginning of the task the pattern of task-related functional activity reached after practice in the group having received standard instructions. We interpret our results in terms of an immediate establishment of an automatic, bottom-up form of inhibitory control by implementation intentions, supported by stimulus-driven retrieval of verbally encoded stimulus-response mapping rules, which in turn triggered inhibitory processes.

Training inhibitory control, the ability to suppress motor or cognitive processes, not only enhances inhibition processes, but also reduces the perceived value and behaviors toward the stimuli associated with the inhibition goals during the practice. While these findings suggest that inhibitory control training interacts with the aversive and reward systems, the underlying spatio-temporal brain mechanisms remain unclear. We used electrical neuroimaging analyses of event-related potentials to examine the plastic brain modulations induced by training healthy participants to inhibit their responses to rewarding (pleasant chocolate) versus aversive food pictures (unpleasant vegetables) with Go/NoGo tasks. Behaviorally, the training resulted in a larger improvement in the aversive than in the rewarding NoGo stimuli condition, suggesting that reward responses impede inhibitory control learning. The electrophysiological results also revealed an interaction between reward responses and inhibitory control plasticity: we observed different effects of practice on the rewarding vs. aversive NoGo stimuli at 200 ms post-stimulus onset, when the conflicts between automatic response tendency and task demands for response inhibition are processed. Electrical source analyses revealed that this effect was driven by an increase in right orbito-cingulate and a decrease in temporo-parietal activity to the rewarding NoGo stimuli and the reverse pattern to the aversive stimuli. Our collective results provide direct neurophysiological evidence for interactions between stimulus reward value and executive control training, and suggest that changes in the assessment of stimuli with repeated motoric inhibition likely follow from associative learning and behavior-stimulus conflicts reduction mechanisms.

How executive function training paradigms can be effectively designed to promote a transfer of the effects of interventions to untrained tasks remains unclear. Here, we tested the hypothesis that training with a complex task involving motor, perceptual and task-set control components would result in more transfer than training with a simple motor control task, because the Complex training would lead to more involvement— and in turn modification—of domain-general executive control networks.We compared performance and electrophysiological activity before and after 10 days of executive control training with the complex (n = 18) versus the simple task (n = 17). We further assessed the effect of the two training regimens on untrained executive tasks involving or not one of the trained control components. A passive control group (n = 19) was used to assess retest effects.Both training groups improved at the trained task but exhibited different plastic changes within left-lateralized and medial frontal areas at 200–250 ms post-stimulus onset. However, contrary to our hypotheses, they showed equivalent improvement to the passive group to the transfer tasks.Our collective results reveal that the effect of training with a task involving multiple executive control components is highly specific to the trained task, even when the training modifies the functional networks underlying the trained executive components. Our findings corroborate current evidence that general cognitive enhancement cannot be achieved with training, even when the interventions modify domain-general brain areas.

Background: Comprehension deficits are more pervasive in aphasic syndromes than initially believed. They affect differentially distinct levels of auditory-verbal comprehension. Current evidence from functional imaging studies in healthy subjects indicates that distinct levels of auditory-verbal analysis involve specific networks.Aims: The aim of this study is (1) to assess the different levels of auditory-verbal analysis with real-time monitoring tasks in patients with aphasia, (2) to compare the performance profiles across aphasia types, (3) to analyse patterns of dissociations vs. co-occurrence at specific levels, and (4) to establish correlations between disturbances at specific levels of auditory-verbal analysis and sites of lesions.Methods & Procedures: Forty-two right-handed patients with aphasia associated with a first unilateral left-hemispheric lesion underwent tests monitoring (1) phonetic-phonological, (2) lexical, (3) morphosyntactic, (4) semantic-pragmatic (at sentence level), and (5)...

Inhibitory control deficits represent a key aspect of the cognitive declines associated with aging. Practicing inhibitory control has thus been advanced as a potential approach to compensate for age-induced neurocognitive impairments. Yet, the functional brain changes associated with practicing inhibitory control tasks in older adults and whether they differ from those observed in young populations remains unresolved.We compared electrical neuroimaging analyses of ERPs recorded during a Go/NoGo practice session with a Group (Young; Older adults) by Session (Beginning; End of the practice) design to identify whether the practice of an inhibition task in older adults reinforces already implemented compensatory activity or reduce it by enhancing the functioning of the brain networks primarily involved in the tasks.We observed an equivalent small effect of practice on performance in the two age-groups. The topographic ERP analyses and source estimations revealed qualitatively different effects of the practice over the N2 and P3 ERP components, respectively driven by a decrease in supplementary motor area activity and an increase in left ventrolateral prefrontal activity in the older but not in the young adults with practice.Our results thus indicate that inhibition task practice in older adults increases age-related divergences in the underlying functional processes.

Exaggerated attentional biases toward specific elements of the environment contribute to the maintenance of several psychiatric conditions, such as biases to threatening faces in social anxiety. Although recent literature indicates that attentional bias modification may constitute an effective approach for psychiatric remediation, the underlying neurophysiological mechanisms remain unclear. We addressed this question by recording EEG in 24 healthy participants performing a modified dot-probe task in which pairs of neutral cues (colored shapes) were replaced by probe stimuli requiring a discrimination judgment. To induce an attentional bias toward or away from the cues, the probes were systematically presented either at the same or at the opposite position of a specific cue color. This paradigm enabled participants to spontaneously develop biases to initially unbiased, neutral cues, as measured by the response speed to the probe presented after the cues. Behavioral result indicated that the ABM procedure induced approach and avoidance biases. The influence of ABM on inhibitory control was assessed in a separated Go/NoGo task: changes in AB did not influence participants' capacity to inhibit their responses to the cues. Attentional bias modification was associated with a topographic modulation of event-related potentials already 50–84 ms following the onset of the cues. Statistical analyses of distributed electrical source estimations revealed that the development of attentional biases was associated with decreased activity in the left temporo-parieto-occipital junction. These findings suggest that attentional bias modification affects early sensory processing phases related to the extraction of information based on stimulus saliency.

Word retrieval in bilingual speakers partly depends on executive-control systems in the left prefrontal cortex - including dorsolateral prefrontal cortex (DLPFC). We tested the hypothesis that DLPFC modulates word production of words specifically in a second language (L2) by measuring the effects of anodal transcranial direct current stimulation (anodal-tDCS) over the DLPFC on picture naming and word translation and on Event Related Potentials (ERPs) and their sources. Twenty-six bilingual participants with ‘unbalanced’ proficiency in two languages were given 20 minutes of 1.5mA anodal or sham tDCS (double-blind stimulation design, counterbalanced stimulation order, one-week intersession delay). The participants then performed the following tasks: verbal and non-verbal fluency during anodal t-DCS stimulation and first and second language (L1 and L2) picture naming and translation (forward (L1→L2) and backward (L2→L1)) immediately after stimulation. The EEG was recorded during picture naming and translation. On the behavioral level, anodal-tDCS had an influence on non-verbal fluency but neither on verbal fluency, nor on picture naming and translation. EEG measures revealed significant interactions between Language and Stimulation on picture naming around 380 ms post stimulus onset and Translation direction and Stimulation on translation around 530 ms post stimulus onset. These effects suggest that L2 phonological retrieval and phoneme encoding are spatially and temporally segregated in the brain. We conclude that anodal-tDCS stimulation has an effect at a neural level on phonological processes and, critically, that DLPFC-mediated activation is a constraint on language production specifically in L2.

Background. A successful interplay between prefrontal and domain-specific language areas is critical for language processing. Previous studies involving people with aphasia have shown that executive control processes might act on lexical-semantic representations during retrieval. Modulating the prefrontal control network by means of noninvasive brain stimulation might, therefore, improve lexical access in people with aphasia. Objective. The present study investigates the effects of prefrontal transcranial direct current stimulation (tDCS) on lexical access in chronic poststroke aphasia. Methods. We report data of 14 participants with chronic poststroke aphasia. We used a sham-tDCS (S-tDCS) controlled and double-blind within-subjects design. Performances in picture naming, verbal fluency, and word repetition were assessed immediately after stimulation. Results. As compared with S-tDCS, anodal tDCS (A-tDCS) improved verbal fluency as well as the speed of naming high frequency words, but not word repetition. Conclusion. The results of our study suggest that the brain network dedicated to lexical retrieval processing can be facilitated by A-tDCS over the left dorsolateral prefrontal cortex. This finding supports the notion that strengthening executive control functions after stroke could complement speech and language-focused therapy.

Whether and how the capacity to inhibit cognitive and motor processes can be trained and the underlying neuroplastic mechanisms remain unclear. Using electrical neuroimaging methods, we investigated how inhibitory control training regimens can be designed to enhance frontal top-down inhibition processes. We trained participants with a Go/NoGo task in which the stimulus–response mapping rules were systematically varied. This task parameter has indeed be hypothesized to determine the extent to which top-down frontal inhibition processes are involved and thus ultimately reinforced during the training. The effects of training on inhibitory control were assessed by analyzing the event-related potentials (ERPs) measured during the Go/NoGo task with a data-driven time- and electrode-wise 2 × 2 ANOVA with factors Session (beginning; end of the training) and Stimuli (Go; NoGo). To localize the sources of the ERP effects in the brain, the same statistical design was applied to distributed electrical source estimations averaged over the periods of ERP modulations. The training improved inhibitory control performance. Electrophysiologically, we found a significant Session × Stimulus interaction at 300–400 ms post-stimulus onset over centro-occipital electrodes. Statistical parametric mapping on the brain source estimations revealed an interaction within right inferior frontal cortices driven by a decrease in response strength to NoGo but not to Go trials in this region. Our collective results demonstrate that frontal top-down inhibition processes can be enhanced with specifically designed inhibitory control training regimens.

Based on findings for overlapping representations of bilingual people's first (L1) and second (L2) languages, unilingual therapies of bilingual aphasia have been proposed to benefit the untrained language. However, the generalisation patterns of intra- and cross-language and phonological therapy and their neural bases remain unclear. We tested whether the effects of an intensive lexical-phonological training (LPT) in L2 transferred to L1 word production in a Persian-French bilingual stroke patient with Broca's aphasia. Language performance was assessed using the Bilingual Aphasia Test, a 144-item picture naming (PN) task and a word–picture verification (WPV) task. Electroencephalography (EEG) was recorded during PN and WPV in both languages before and after an LPT in French on a wordlist from the PN task. After the therapy, naming improved only for the treated L2 items. The naming performance improved neither in the untrained L2 items nor in the corresponding items in L1. EEG analyses revealed a Language x Session topographic interaction at 540 ms post-stimulus, driven by a modification of the electrophysiological response to the treated L2 but not L1 items. These results indicate that LPT modified the brain networks engaged in the phonological-phonetic processing during naming only in the trained language for the trained items.

Ample evidence indicates that inhibitory control (IC), a key executive component referring to the ability to suppress cognitive or motor processes, relies on a right‐lateralized fronto‐basal brain network. However, whether and how IC can be improved with training and the underlying neuroplastic mechanisms remains largely unresolved. We used functional and structural magnetic resonance imaging to measure the effects of 2 weeks of training with a Go/NoGo task specifically designed to improve frontal top‐down IC mechanisms. The training‐induced behavioral improvements were accompanied by a decrease in neural activity to inhibition trials within the right pars opercularis and triangularis, and in the left pars orbitalis of the inferior frontal gyri. Analyses of changes in brain anatomy induced by the IC training revealed increases in grey matter volume in the right pars orbitalis and modulations of white matter microstructure in the right pars triangularis. The task‐specificity of the effects of training was confirmed by an absence of change in neural activity to a control working memory task. Our combined anatomical and functional findings indicate that differential patterns of functional and structural plasticity between and within inferior frontal gyri enhanced the speed of top‐down inhibition processes and in turn IC proficiency. The results suggest that training‐based interventions might help overcoming the anatomic and functional deficits of inferior frontal gyri manifesting in inhibition‐related clinical conditions. More generally, we demonstrate how multimodal neuroimaging investigations of training‐induced neuroplasticity enable revealing novel anatomo‐functional dissociations within frontal executive brain networks. Hum Brain Mapp 36:2527–2543, 2015. © 2015 Wiley Periodicals, Inc.

Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256-channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio-temporal dynamics of the brain response to visual checkerboard stimuli (Experiment 1) or blank stimuli (Experiment 2) presented without a mask for 1 ms (visible), 500 µs (partially visible), and 250 µs (subliminal) by applying time-wise, assumption-free nonparametric randomization statistics on the strength and on the topography of high-density scalp-recorded electric field. Stimulus visibility was assessed in a third separate behavioral experiment. Results revealed that unmasked checkerboards presented subliminally for 250 µs evoked weak but detectable visual evoked potential (VEP) responses. When the checkerboards were replaced by blank stimuli, there was no evidence for the presence of an evoked response anymore. Furthermore, the checkerboard VEPs were modulated topographically between 243 and 296 ms post-stimulus onset as a function of stimulus duration, indicative of the engagement of distinct configuration of active brain networks. A distributed electrical source analysis localized this modulation within the right superior parietal lobule near the precuneus. These results show the presence of a brain response to submillisecond unmasked subliminal visual stimuli independently of their emotional saliency or meaningfulness and opens an avenue for new investigations of subliminal stimulation without using visual masking.

Task-irrelevant information is constantly present in our environment and may interfere with the processing of the information necessary to achieve goal-directed behavior. While task goals determine which information must be suppressed, the demand for inhibitory control depends on the strength of the interference induced by incoming, task-irrelevant information. Whether the same or distinct inhibitory processes are engaged to suppress various degrees of interference from task-irrelevant information remains largely unresolved. We investigated this question by manipulating the strength of the conflict induced by automatic word reading in a classical color Stroop task. High conflict was induced by presenting words in participant’s native language and low conflict by presenting words in a less familiar language. Behavioral performance and electrical neuroimaging analyses of event-related potentials to the words were analyzed following a two-by-two within-subject design with factors conflict strength (high; low) and color word/word ink congruency (congruent; incongruent). Behaviorally, we observed a significant conflict strength × congruency driven by a smaller Stroop effect in the low- than high conflict condition. Electrophysiologically, we observed a significant conflict strength × congruency interaction at the topographic level during the period of the N450 components, indicative of the engagement of distinct configurations of brain networks. No such interaction was found at the level of response strength. Electrical sources analyses localized the topographic effect within the anterior cingulate cortex and basal ganglia, left middle frontal and occipital areas. We interpret our results in terms of qualitatively distinct executive mechanisms for reactive inhibitory control in conditions of high versus low stimulus-driven conflict.

INTRODUCTION Inhibitory control refers to our ability to suppress ongoing motor affective or cognitive processes and mostly depends on a fronto basal brain network. Inhibitory control deficits participate in the emergence of several prominent psychiatric conditions including attention deficit/hyperactivity disorder or addiction. The rehabilitation of these pathologies might therefore benefit from training based behavioral interventions aiming at improving inhibitory control proficiency and normalizing the underlying neurophysiological mechanisms. The development of an efficient inhibitory control training regimen first requires determining the effects of practicing inhibition tasks. METHODS We addressed this question by contrasting behavioral performance and electrical neuroimaging analyses of event related potentials (ERPs) recorded from humans at the beginning versus the end of 1 h of practice on a stop signal task (SST) involving the withholding of responses when a stop signal was presented during a speeded auditory discrimination task. RESULTS Practicing a short SST improved behavioral performance. Electrophysiologically ERPs differed topographically at 200 msec post stimulus onset indicative of the engagement of distinct brain network with learning. Source estimations localized this effect within the inferior frontal gyrus the pre supplementary motor area and the basal ganglia. CONCLUSION Our collective results indicate that behavioral and brain responses during an inhibitory control task are subject to fast plastic changes and provide evidence that high order fronto basal executive networks can be modified by practicing a SST.

Behavioral and brain responses to stimuli not only depend on their physical features but also on the individuals' neurocognitive states before stimuli onsets. While the influence of pre-stimulus fluctuations in brain activity on low-level perceptive processes is well established, the state dependency of high-order executive processes remains unclear. Using a classical inhibitory control Go/NoGo task, we examined whether and how fluctuations in the brain activity during the period preceding the stimuli triggering inhibition influenced inhibitory control performance. Seventeen participants completed the Go/NoGo task while 64-channel electroencephalogram was recorded. We compared the event-related potentials preceding the onset of the NoGo stimuli associated with inhibition failures false alarms (FA) vs. successful inhibition correct rejections (CR) with data-driven statistical analyses of global measures of the topography and strength of the scalp electric field. Distributed electrical source estimations were used to localize the origin of the event-related potentials modulations. We observed differences in the global field power of the event-related potentials (FA > CR) without concomitant topographic modulations over the 40 ms period immediately preceding NoGo stimuli. This result indicates that the same brain networks were engaged in the two conditions, but more strongly before FA than CR. Source estimations revealed that this effect followed from a higher activity before FA than CR within bilateral inferior frontal gyri and the right inferior parietal lobule. These findings suggest that uncontrolled quantitative variations in pre-stimulus activity within attentional and control brain networks influence inhibition performance. The present data thereby demonstrate the state dependency of cognitive processes of up to high- order executive levels.

Verbal fluency refers to the ability to generate as many words as possible in a limited time interval, without repetition and according to either a phonologic (each word begins with a given letter) or a semantic rule (each word belongs to a given semantic category). While current literature suggests the involvement of left fronto-temporal structures in fluency tasks, whether the same or distinct brain areas are necessary for each type of fluency remains unclear.We tested the hypothesis for an involvement of partly segregated cortico-subcortical structures between phonologic and semantic fluency by examining with a voxel-based lesion symptom mapping approach the effects of brain lesions on fluency scores corrected for age and education level in a group of 191 unselected brain-damaged patients with a first left or right hemispheric lesion.There was a positive correlation between the scores to the two types of fluency, suggesting that common mechanisms underlie the word generation independent of the production rule. The lesion-symptom mapping revealed that lesions to left basal ganglia impaired both types of fluency and that left superior temporal, supramarginal and rolandic operculum lesions selectively impaired phonologic fluency and left middle temporal lesions impaired semantic fluency.Our results corroborate current neurocognitive models of word retrieval and production, and refine the role of cortical- subcortical interaction in lexical search by highlighting the common executive role of basal ganglia in both types of verbal fluency and the preferential involvement of the ventral and dorsal language pathway in semantic and phonologic fluency, respectively.

In natural settings the same sound source is often heard repeatedly, with variations in spectro-temporal and spatial characteristics. We investigated how such repetitions influence sound representations and in particular how auditory cortices keep track of recently vs. often heard objects. A set of 40 environmental sounds was presented twice, i.e. as prime and as repeat, while subjects categorized the corresponding sound sources as living vs. non-living. Electrical neuroimaging analyses were applied to auditory evoked potentials (AEPs) comparing primes vs. repeats (effect of presentation) and the four experimental sections. Dynamic analysis of distributed source estimations revealed i) a significant main effect of presentation within the left temporal convexity at 164–215 ms post-stimulus onset; and ii) a significant main effect of section in the right temporo-parietal junction at 166–213 ms. A 3-way repeated measures ANOVA (hemisphere × presentation × section) applied to neural activity of the above clusters during the common time window confirmed the specificity of the left hemisphere for the effect of presentation, but not that of the right hemisphere for the effect of section. In conclusion, spatio-temporal dynamics of neural activity encode the temporal history of exposure to sound objects. Rapidly occurring plastic changes within the semantic representations of the left hemisphere keep track of objects heard a few seconds before, independent of the more general sound exposure history. Progressively occurring and more long-lasting plastic changes occurring predominantly within right hemispheric networks, which are known to code for perceptual, semantic and spatial aspects of sound objects, keep track of multiple exposures.

Discriminating complex sounds relies on multiple stages of differential brain activity. The specific roles of these stages and their links to perception were the focus of the present study. We presented 250 ms duration sounds of living and man-made objects while recording 160-channel electroencephalography (EEG). Subjects categorized each sound as that of a living, man-made or unknown item. We tested whether/when the brain discriminates between sound categories even when not transpiring behaviorally. We applied a single-trial classifier that identified voltage topographies and latencies at which brain responses are most discriminative. For sounds that the subjects could not categorize, we could successfully decode the semantic category based on differences in voltage topographies during the 116–174 ms post-stimulus period. Sounds that were correctly categorized as that of a living or man-made item by the same subjects exhibited two periods of differences in voltage topographies at the single-trial level. Subjects exhibited differential activity before the sound ended (starting at 112 ms) and on a separate period at ~ 270 ms post-stimulus onset. Because each of these periods could be used to reliably decode semantic categories, we interpreted the first as being related to an implicit tuning for sound representations and the second as being linked to perceptual decision-making processes. Collectively, our results show that the brain discriminates environmental sounds during early stages and independently of behavioral proficiency and that explicit sound categorization requires a subsequent processing stage.

In highly proficient, early bilinguals, behavioural studies of the cost of switching language or task suggest qualitative differences between language control and domain-general cognitive control. By contrast, several neuroimaging studies have shown an overlap of the brain areas involved in language control and domain-general cognitive control. The current study measured both behavioural responses and event-related potentials (ERPs) from bilinguals who performed picture naming in single- or mixed-language contexts, as well as an alphanumeric categorisation task in single- or mixed-task context. Analysis of switch costs during the mixed-context conditions showed qualitative differences between language control and domain-general cognitive control. A 2 × 2 ANOVA of the ERPs, with domain (linguistic, alphanumeric) and context (single, mixed) as within-participant factors, revealed a significant interaction, which also suggests a partly independent language-control mechanism. Source estimations revealed the neural basis of this mechanism to be in bilateral frontal–temporal areas.

Behavioral and brain responses to identical stimuli can vary with experimental and task parameters, including the context of stimulus presentation or attention. More surprisingly, computational models suggest that noise-related random fluctuations in brain responses to stimuli would alone be sufficient to engender perceptual differences between physically identical stimuli. In two experiments combining psychophysics and EEG in healthy humans, we investigated brain mechanisms whereby identical stimuli are (erroneously) perceived as different (higher vs lower in pitch or longer vs shorter in duration) in the absence of any change in the experimental context. Even though, as expected, participants' percepts to identical stimuli varied randomly, a classification algorithm based on a mixture of Gaussians model (GMM) showed that there was sufficient information in single-trial EEG to reliably predict participants' judgments of the stimulus dimension. By contrasting electrical neuroimaging analyses of auditory evoked potentials (AEPs) to the identical stimuli as a function of participants' percepts, we identified the precise timing and neural correlates (strength vs topographic modulations) as well as intracranial sources of these erroneous perceptions. In both experiments, AEP differences first occurred ∼100 ms after stimulus onset and were the result of topographic modulations following from changes in the configuration of active brain networks. Source estimations localized the origin of variations in perceived pitch of identical stimuli within right temporal and left frontal areas and of variations in perceived duration within right temporoparietal areas. We discuss our results in terms of providing neurophysiologic evidence for the contribution of random fluctuations in brain activity to conscious perception.

The human auditory system is comprised of specialized but interacting anatomic and functional pathways encoding object, spatial, and temporal information. We review how learning-induced plasticity manifests along these pathways and to what extent there are common mechanisms subserving such plasticity. A first series of experiments establishes a temporal hierarchy along which sounds of objects are discriminated along basic to fine-grained categorical boundaries and learned representations. A widespread network of temporal and (pre)frontal brain regions contributes to object discrimination via recursive processing. Learning-induced plasticity typically manifested as repetition suppression within a common set of brain regions. A second series considered how the temporal sequence of sound sources is represented. We show that lateralized responsiveness during the initial encoding phase of pairs of auditory spatial stimuli is critical for their accurate ordered perception. Finally, we consider how spatial representations are formed and modified through training-induced learning. A population-based model of spatial processing is supported wherein temporal and parietal structures interact in the encoding of relative and absolute spatial information over the initial ∼300 ms post-stimulus onset. Collectively, these data provide insights into the functional organization of human audition and open directions for new developments in targeted diagnostic and neurorehabilitation strategies.

Auditory spatial functions, including the ability to discriminate between the positions of nearby sound sources, are subserved by a large temporo-parieto-frontal network. With the aim of determining whether and when the parietal contribution is critical for auditory spatial discrimination, we applied single pulse transcranial magnetic stimulation on the right parietal cortex 20, 80, 90 and 150 ms post-stimulus onset while participants completed a two-alternative forced choice auditory spatial discrimination task in the left or right hemispace. Our results reveal that transient TMS disruption of right parietal activity impairs spatial discrimination when applied at 20 ms post-stimulus onset for sounds presented in the left (controlateral) hemispace and at 80 ms for sounds presented in the right hemispace. We interpret our finding in terms of a critical role for controlateral temporo-parietal cortices over initial stages of the building-up of auditory spatial representation and for a right hemispheric specialization in integrating the whole auditory space over subsequent, higher-order processing stages.

Evidence from human and non-human primate studies supports a dual-pathway model of audition, with partially segregated cortical networks for sound recognition and sound localisation, referred to as the What and Where processing streams. In normal subjects, these two networks overlap partially on the supratemporal plane. suggesting that some early-stage auditory areas are involved in processing of either auditory feature alone or of both. Using high-resolution 7-T fMRI we have investigated the influence of positional information on sound object representations by comparing activation patterns to environmental sounds lateralised to the right or left ear. While unilaterally presented sounds induced bilateral activation, small clusters in specific non-primary auditory areas were significantly, more activated by contra-laterally presented stimuli. Comparison of these data with histologically identified non-primary auditory areas suggests that the coding of sound objects within early-stage auditory areas lateral and posterior to primary auditory cortex AI is modulated by the position of the sound, while that within anterior areas is not. (C) 2010 Elsevier Inc. All rights reserved.

Optimal behavior relies on flexible adaptation to environmental requirements, notably based on the detection of errors. The impact of error detection on subsequent behavior typically manifests as a slowing down of RTs following errors. Precisely how errors impact the processing of subsequent stimuli and in turn shape behavior remains unresolved. To address these questions, we used an auditory spatial go/no-go task where continual feedback informed participants of whether they were too slow. We contrasted auditory-evoked potentials to left-lateralized go and right no-go stimuli as a function of performance on the preceding go stimuli, generating a 2 × 2 design with “preceding performance” (fast hit [FH], slow hit [SH]) and stimulus type (go, no-go) as within-subject factors. SH trials yielded SH trials on the following trials more often than did FHs, supporting our assumption that SHs engaged effects similar to errors. Electrophysiologically, auditory-evoked potentials modulated topographically as a function of preceding performance 80–110 msec poststimulus onset and then as a function of stimulus type at 110–140 msec, indicative of changes in the underlying brain networks. Source estimations revealed a stronger activity of prefrontal regions to stimuli after successful than error trials, followed by a stronger response of parietal areas to the no-go than go stimuli. We interpret these results in terms of a shift from a fast automatic to a slow controlled form of inhibitory control induced by the detection of errors, manifesting during low-level integration of task-relevant features of subsequent stimuli, which in turn influences response speed.

Accurate perception of the temporal order of sensory events is a prerequisite in numerous functions ranging from language comprehension to motor coordination. We investigated the spatio-temporal brain dynamics of auditory temporal order judgment (aTOJ) using electrical neuroimaging analyses of auditory evoked potentials (AEPs) recorded while participants completed a near-threshold task requiring spatial discrimination of left–right and right–left sound sequences. AEPs to sound pairs modulated topographically as a function of aTOJ accuracy over the 39–77 ms post-stimulus period, indicating the engagement of distinct configurations of brain networks during early auditory processing stages. Source estimations revealed that accurate and inaccurate performance were linked to bilateral posterior sylvian regions activity (PSR). However, activity within left, but not right, PSR predicted behavioral performance suggesting that left PSR activity during early encoding phases of pairs of auditory spatial stimuli appears critical for the perception of their order of occurrence. Correlation analyses of source estimations further revealed that activity between left and right PSR was significantly correlated in the inaccurate but not accurate condition, indicating that aTOJ accuracy depends on the functional decoupling between homotopic PSR areas. These results support a model of temporal order processing wherein behaviorally relevant temporal information – i.e. a temporal ‘stamp’ – is extracted within the early stages of cortical processes within left PSR but critically modulated by inputs from right PSR. We discuss our results with regard to current models of temporal of temporal order processing, namely gating and latency mechanisms.

Prefrontal anodal transcranial direct current stimulation (tDCS) has been proposed as a potential approach to improve inhibitory control performance. The functional consequences of tDCS during inhibition tasks remain, however, largely unresolved. We addressed this question by analyzing functional magnetic resonance imaging (fMRI) recorded while participants completed a Go/NoGo task after right-lateralized prefrontal anodal tDCS with a crossover, sham-controlled, double-blind experimental design. We replicated previous evidence for an absence of offline effect of anodal stimulation on Go/NoGo performance. The fMRI results revealed a larger increase in right ventrolateral prefrontal activity for Go than NoGo trials in the anodal than sham condition. This pattern suggests that tDCS-induced increases in cortical excitability have larger effects on fMRI activity in regions with a lower task-related engagement. This was the case for the right prefrontal cortex in the Go condition in our task because while reactive inhibition was not engaged during execution trials, the unpredictability of the demand for inhibitory control still incited an engagement of proactive inhibition. Exploratory analyses further revealed that right prefrontal stimulation interacted with task-related functional demands in the supplementary motor area and the thalamus. Our collective results emphasize the dependency of offline tDCS functional effects on the task-related engagement of the stimulated areas and suggest that this factor might partly account for the discrepancies in the functional effects of tDCS observed in previous studies.

Accurate perception of the order of occurrence of sensory information is critical for the building up of coherent representations of the external world from ongoing flows of sensory inputs. While some psychophysical evidence reports that performance on temporal perception can improve, the underlying neural mechanisms remain unresolved. Using electrical neuroimaging analyses of auditory evoked potentials (AEPs), we identified the brain dynamics and mechanism supporting improvements in auditory temporal order judgment (TOJ) during the course of the first vs. latter half of the experiment. Training-induced changes in brain activity were first evident 43–76 ms post stimulus onset and followed from topographic, rather than pure strength, AEP modulations. Improvements in auditory TOJ accuracy thus followed from changes in the configuration of the underlying brain networks during the initial stages of sensory processing. Source estimations revealed an increase in the lateralization of initially bilateral posterior sylvian region (PSR) responses at the beginning of the experiment to left-hemisphere dominance at its end. Further supporting the critical role of left and right PSR in auditory TOJ proficiency, as the experiment progressed, responses in the left and right PSR went from being correlated to un-correlated. These collective findings provide insights on the neurophysiologic mechanism and plasticity of temporal processing of sounds and are consistent with models based on spike timing dependent plasticity.

Sound localization relies on the analysis of interaural time and intensity differences, as well as attenuation patterns by the outer ear. We investigated the relative contributions of interaural time and intensity difference cues to sound localization by testing 60 healthy subjects: 25 with focal left and 25 with focal right hemispheric brain damage. Group and single-case behavioural analyses, as well as anatomo-clinical correlations, confirmed that deficits were more frequent and much more severe after right than left hemispheric lesions and for the processing of interaural time than intensity difference cues. For spatial processing based on interaural time difference cues, different error types were evident in the individual data. Deficits in discriminating between neighbouring positions occurred in both hemispaces after focal right hemispheric brain damage, but were restricted to the contralesional hemispace after focal left hemispheric brain damage. Alloacusis (perceptual shifts across the midline) occurred only after focal right hemispheric brain damage and was associated with minor or severe deficits in position discrimination. During spatial processing based on interaural intensity cues, deficits were less severe in the right hemispheric brain damage than left hemispheric brain damage group and no alloacusis occurred. These results, matched to anatomical data, suggest the existence of a binaural sound localization system predominantly based on interaural time difference cues and primarily supported by the right hemisphere. More generally, our data suggest that two distinct mechanisms contribute to: (i) the precise computation of spatial coordinates allowing spatial comparison within the contralateral hemispace for the left hemisphere and the whole space for the right hemisphere; and (ii) the building up of global auditory spatial representations in right temporo-parietal cortices.

The rapid and precise processing of environmental sounds contributes to communication functions as well as both object recognition and localization. Plasticity in (accessing) the neural representations of environmental sounds is likewise essential for an adaptive organism, in particular humans, and can be indexed by repetition priming. How the brain achieves such plasticity with representations of environmental sounds is presently unresolved. Electrical neuroimaging of 64-channel auditory evoked potentials (AEPs) in humans identified the spatio-temporal brain mechanisms of repetition priming involving sounds of environmental objects. Subjects performed an ‘oddball’ target detection task, based on the semantic category of stimuli (living vs. man-made objects). Repetition priming effects were observed behaviorally as a speeding of reaction times and electrophysiologically as a suppression of the strength of responses to repeated sound presentations over the 156–215 ms post-stimulus period. These effects of plasticity were furthermore localized, using statistical analyses of a distributed linear inverse solution, to the left middle temporal gyrus and superior temporal sulcus (BA22), which have been implicated in associating sounds with their abstract representations and actions. These effects are subsequent to and occur in different brain regions from what has been previously identified as the earliest discrimination of auditory object categories. Plasticity in associative-semantic, rather than perceptual-discriminative functions, may underlie repetition priming of sounds of objects. We present a multi-stage mechanism of auditory object processing akin to what has been described for visual object processing and which also provides a framework for accessing multisensory object representations.

Unilateral extinction of auditory stimuli, a key feature of the neglect syndrome, was investigated in 15 patients with right (11), left (3) or bilateral (1) hemispheric lesions using a verbal dichotic condition, in which each ear received simultaneously one word, and a interaural-time-difference (ITD) diotic condition, in which both ears received both words lateralised by means of ITD. Additional investigations included sound localisation, visuo-spatial attention and general cognitive status. Five patients presented a significant asymmetry in the ITD diotic test, due to a decrease of left hemispace reporting but no asymmetry was found in dichotic listening. Six other patients presented a significant asymmetry in the dichotic test due to a significant decrease of left or right ear reporting, but no asymmetry in diotic listening. Ten of the above patients presented mild to severe deficits in sound localisation and eight signs of visuo-spatial neglect (three with selective asymmetry in the diotic and five in the dichotic task). Four other patients presented a significant asymmetry in both the diotic and dichotic listening tasks. Three of them presented moderate deficits in localisation and all four moderate visuo-spatial neglect. Thus, extinction for left ear and left hemispace can double dissociate, suggesting distinct underlying neural processes. Furthermore, the co-occurrence with sound localisation disturbance and with visuo-spatial hemineglect speaks in favour of the involvement of multisensory attentional representations.

Interactions between stimuli's acoustic features and experience-based internal models of the environment enable listeners to compensate for the disruptions in auditory streams that are regularly encountered in noisy environments. However, whether auditory gaps are filled in predictively or restored a posteriori remains unclear. The current lack of positive statistical evidence that internal models can actually shape brain activity as would real sounds precludes accepting predictive accounts of filling-in phenomenon. We investigated the neurophysiological effects of internal models by testing whether single-trial electrophysiological responses to omitted sounds in a rule-based sequence of tones with varying pitch could be decoded from the responses to real sounds and by analyzing the ERPs to the omissions with data-driven electrical neuroimaging methods. The decoding of the brain responses to different expected, but omitted, tones in both passive and active listening conditions was above chance based on the responses to the real sound in active listening conditions. Topographic ERP analyses and electrical source estimations revealed that, in the absence of any stimulation, experience-based internal models elicit an electrophysiological activity different from noise and that the temporal dynamics of this activity depend on attention. We further found that the expected change in pitch direction of omitted tones modulated the activity of left posterior temporal areas 140–200 msec after the onset of omissions. Collectively, our results indicate that, even in the absence of any stimulation, internal models modulate brain activity as do real sounds, indicating that auditory filling in can be accounted for by predictive activity.

Neuropsychological theories raise the question if in late bilinguals with dementia of the Alzheimer type (DAT), the second language (L2) may be more impaired than the first (L1). We compared language performance in different tasks of oral comprehension (semantic and syntactic) and production (naming, repetition and fluency) in L1 and L2 in a group of 13 late proficient bilinguals wit DAT immersion, and a matched control group of 12 healthy late bilinguals. Two-way mixed repeated-measure ANOVAs with factors Language and Group revealed main effects of Group (p < .05) indicating that DAT affects all aspects of language. There was no Group × Language interaction, suggesting that DAT affects both languages similarly. Our study thus shows that neurodegenerative diseases affect L1 and L2 in a parallel manner, particularly at the levels of semantic, lexical and syntactic processing. These results speak in favour of a shared L1 and L2 network in late bilinguals.

Referred to as orthographic depth, the degree of consistency of grapheme/phoneme correspondences varies across languages from high in shallow orthographies to low in deep orthographies. The present study investigates the impact of orthographic depth on reading route by analyzing evoked potentials to words in a deep (French) and shallow (German) language presented to highly proficient bilinguals. ERP analyses to German and French words revealed significant topographic modulations 240–280 ms post-stimulus onset, indicative of distinct brain networks engaged in reading over this time window. Source estimations revealed that these effects stemmed from modulations of left insular, inferior frontal and dorsolateral regions (German > French) previously associated to phonological processing. Our results show that reading in a shallow language was associated to a stronger engagement of phonological pathways than reading in a deep language. Thus, the lexical pathways favored in word reading are reinforced by phonological networks more strongly in the shallow than deep orthography.

Multisensory interactions have been documented within low-level, even primary, cortices and at early post-stimulus latencies. These effects are in turn linked to behavioral and perceptual modulations. In humans, visual cortex excitability, as measured by transcranial magnetic stimulation (TMS) induced phosphenes, can be reliably enhanced by the co-presentation of sounds. This enhancement occurs at pre-perceptual stages and is selective for different types of complex sounds. However, the source(s) of auditory inputs effectuating these excitability changes in primary visual cortex remain disputed. The present study sought to determine if direct connections between low-level auditory cortices and primary visual cortex are mediating these kinds of effects by varying the pitch and bandwidth of the sounds co-presented with single-pulse TMS over the occipital pole. Our results from 10 healthy young adults indicate that both the central frequency and bandwidth of a sound independently affect the excitability of visual cortex during processing stages as early as 30 msec post-sound onset. Such findings are consistent with direct connections mediating early-latency, low-level multisensory interactions within visual cortices.

Deficits in the processing of sensory reafferences have been suggested as accounting for age-related decline in motor coordination. Whether sensory reafferences are accurately processed can be assessed based on the bimanual advantage in tapping: because of tapping with an additional hand increases kinesthetic reafferences, bimanual tapping is characterized by a reduced inter-tap interval variability than unimanual tapping. A suppression of the bimanual advantage would thus indicate a deficit in sensory reafference. We tested whether elderly indeed show a reduced bimanual advantage by measuring unimanual (UM) and bimanual (BM) self-paced tapping performance in groups of young (n = 29) and old (n = 27) healthy adults. Electroencephalogram was recorded to assess the underlying patterns of oscillatory activity, a neurophysiological mechanism advanced to support the integration of sensory reafferences. Behaviorally, there was a significant interaction between the factors tapping condition and age group at the level of the inter-tap interval variability, driven by a lower variability in BM than UM tapping in the young, but not in the elderly group. This result indicates that in self-paced tapping, the bimanual advantage is absent in elderly. Electrophysiological results revealed an interaction between tapping condition and age group on low beta band (14âeuro"20 Hz) activity. Beta activity varied depending on the tapping condition in the elderly but not in the young group. Source estimations localized this effect within left superior parietal and left occipital areas. We interpret our results in terms of engagement of different mechanisms in the elderly depending on the tapping mode: a âeuro~kinestheticâeuro? mechanism for UM and a âeuro~visual imageryâeuro? mechanism for BM tapping movement.

Background The supplementary motor area (SMA) plays a key role in motor programming and production and is involved in internally-cued movements. In neurological populations, SMA syndrome following a lesion to the “SMA proper” is characterized by transient impairment of voluntary movements and motor sequences. This syndrome is assumed to follow on from an interruption of the motor cortico-subcortical loop, and some case reports indicate that such a syndrome could occur after a brain lesion isolating the SMA from subcortical structures. Aim To characterize the pattern of motor impairments in a patient whose stroke disconnects the SMA from the subcortical motor loop. Method A patient developed a moderate transient left hemiparesis following a subcortical stroke in the right anterior cerebral artery area, which disconnected the SMA from basal ganglia. Eight days after the stroke, when the hemiparesis had regressed, the patient presented a specific SMA motor disorder of the left hand which manifested as an akinesia and was exacerbated when his visual attention was not directed towards his hand. We assessed finger tapping with left and right hands, eyes closed and open, in the left and right hemispace. We indexed movement speed as the number of taps filmed over 5-s periods. Results Left motor weakness (grasping strength of right hand: 49 kg and left hand: 41 kg) was resolved in a week. Ideomotor and ideational gestures and motor sequences were preserved. On the tapping task, left-hand tapping was slower than right-hand tapping. Critically, visual feedback improved tapping speed for the left, but not for the right, hand. The hemispace of the task execution had no effect on tapping performance. Conclusion Our results suggest that SMA-basal ganglia disconnection decreases contralateral movement initiation and maintenance and this effect is partly compensated by visual cues.

The rapid stopping of specific parts of movements is frequently required in daily life. Yet, whether selective inhibitory control of movements is mediated by a specific neural pathway or by the combination between a global stopping of all ongoing motor activity followed by the re-initiation of task-relevant movements remains unclear. To address this question, we applied time-wise statistical analyses of the topography, global field power and electrical sources of the event-related potentials to the global vs selective inhibition stimuli presented during a Go/NoGo task. Participants (n = 18) had to respond as fast as possible with their two hands to Go stimuli and to withhold the response from the two hands (global inhibition condition, GNG) or from only one hand (selective inhibition condition, SNG) when specific NoGo stimuli were presented. Behaviorally, we replicated previous evidence for slower response times in the SNG than in the Go condition. Electrophysiologically, there were two distinct phases of event-related potentials modulations between the GNG and the SNG conditions. At 110–150 ms post-stimulus onset, there was a difference in the strength of the electric field without concomitant topographic modulation, indicating the differential engagement of statistically indistinguishable configurations of neural generators for selective and global inhibitory control. At 150–200 ms, there was topographic modulation, indicating the engagement of distinct brain networks. Source estimations localized these effects within bilateral temporo-parieto-occipital and within parieto-central networks, respectively. Our results suggest that while both types of motor inhibitory control depend on global stopping mechanisms, selective and global inhibition still differ quantitatively at early attention-related processing phases.

Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials, a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance. To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited (correct rejection) vs. committed (false alarms) during an auditory spatial Go/NoGo task. We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before false alarms. There was no evidence for an EEG topography occurring more frequently before false alarms than before correct rejections. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network. Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms.

Introduction Behavioral, clinical and neuroimaging evidence indicate that the first (L1) and the second language (L2) of bilingual individuals are supported by partly overlapping anatomo-functional pathways. While in the specific cases of patients suffering from cortical neurodegenerative diseases neuropsychological models predict that, in late bilinguals, L2 could be more impaired than L2, clinical data so far failed to demonstrate such dissociation. Method To address this question, we compared language performance in different tasks of oral and comprehension (semantic and syntactic) and production (naming, repetition, and fluency) in L1 and L2 in a group of 13 late proficient bilinguals with dementia of Alzheimer type (DAT) with 12 healthy late bilinguals matched in several demographic and linguistic factors including education level, age of L2 acquisition and immersion. Results Two-way mixed repeated-measure ANOVAs with factors Language and Group reveal main effects of Group (P

Item does not contain fulltext Following prolonged exposure to adaptor sounds moving in a single direction, participants may perceive stationary-probe sounds as moving in the opposite direction [direction-selective auditory motion aftereffect (aMAE)] and be less sensitive to motion of any probe sounds that are actually moving (motion-sensitive aMAE). The neural mechanisms of aMAEs, and notably whether they are due to adaptation of direction-selective motion detectors, as found in vision, is presently unknown and would provide critical insight into auditory motion processing. We measured human behavioral responses and auditory evoked potentials to probe sounds following four types of moving-adaptor sounds: leftward and rightward unidirectional, bidirectional, and stationary. Behavioral data replicated both direction-selective and motion-sensitive aMAEs. Electrical neuroimaging analyses of auditory evoked potentials to stationary probes revealed no significant difference in either global field power (GFP) or scalp topography between leftward and rightward conditions, suggesting that aMAEs are not based on adaptation of direction-selective motion detectors. By contrast, the bidirectional and stationary conditions differed significantly in the stationary-probe GFP at 200 ms poststimulus onset without concomitant topographic modulation, indicative of a difference in the response strength between statistically indistinguishable intracranial generators. The magnitude of this GFP difference was positively correlated with the magnitude of the motion-sensitive aMAE, supporting the functional relevance of the neurophysiological measures. Electrical source estimations revealed that the GFP difference followed from a modulation of activity in predominantly right hemisphere frontal-temporal-parietal brain regions previously implicated in auditory motion processing. Our collective results suggest that auditory motion processing relies on motion-sensitive, but, in contrast to vision, non-direction-selective mechanisms.

Auditory evoked potentials are informative of intact cortical functions of comatose patients. The integrity of auditory functions evaluated using mismatch negativity paradigms has been associated with their chances of survival. However, because auditory discrimination is assessed at various delays after coma onset, it is still unclear whether this impairment depends on the time of the recording. We hypothesized that impairment in auditory discrimination capabilities is indicative of coma progression, rather than of the comatose state itself and that rudimentary auditory discrimination remains intact during acute stages of coma. We studied 30 post-anoxic comatose patients resuscitated from cardiac arrest and five healthy, age- matched controls. Using a mismatch negativity paradigm, we performed two electroencephalography recordings with a standard 19-channel clinical montage: the first within 24 h after coma onset and under mild therapeutic hypothermia, and the second after 1 day and under normothermic conditions. We analysed electroencephalography responses based on a multivariate decoding algorithm that automatically quantifies neural discrimination at the single patient level. Results showed high average decoding accuracy in discriminating sounds both for control subjects and comatose patients. Importantly, accurate decoding was largely independent of patients’ chance of survival. However, the progression of auditory discrimination between the first and second recordings was informative of a patient’s chance of survival. A deterioration of auditory discrimination was observed in all non- survivors (equivalent to 100% positive predictive value for survivors). We show, for the first time, evidence of intact auditory processing even in comatose patients who do not survive and that progression of sound discrimination over time is informative of a patient’s chance of survival. Tracking auditory discrimination in comatose patients could provide new insight to the chance of awakening in a quantitative and automatic fashion during early stages of coma.

Pantomimes of object use require accurate representations of movements and a selection of the most task-relevant gestures. Prominent models of praxis, corroborated by functional neuroimaging studies, predict a critical role for left parietal cortices in pantomime and advance that these areas store representations of tool use. In contrast, lesion data points to the involvement of left inferior frontal areas, suggesting that defective selection of movement features is the cause of pantomime errors. We conducted a large-scale voxel-based lesion-symptom mapping analyses with configural/spatial (CS) and body-part-as-object (BPO) pantomime errors of 150 left and right brain-damaged patients. Our results confirm the left hemisphere dominance in pantomime. Both types of error were associated with damage to left inferior frontal regions in tumor and stroke patients. While CS pantomime errors were associated with left temporoparietal lesions in both stroke and tumor patients, these errors appeared less associated with parietal areas in stroke than in tumor patients and less associated with temporal in tumor than stroke patients. BPO errors were associated with left inferior frontal lesions in both tumor and stroke patients. Collectively, our results reveal a left intrahemispheric dissociation for various aspects of pantomime, but with an unspecific role for inferior frontal regions.

Both neural and behavioral responses to stimuli are influenced by the state of the brain immediately preceding their presentation, notably by pre-stimulus oscillatory activity. Using frequency analysis of high-density electroencephalogram coupled with source estimations, the present study investigated the role of pre-stimulus oscillatory activity in auditory spatial temporal order judgments (TOJ). Oscillations within the beta range (i.e. 18-23 Hz) were significantly stronger before accurate than inaccurate TOJ trials. Distributed source estimations identified bilateral posterior sylvian regions as the principal contributors to pre-stimulus beta oscillations. Activity within the left posterior sylvian region was significantly stronger before accurate than inaccurate TOJ trials. We discuss our results in terms of a modulation of sensory gating mechanisms mediated by beta activity.

Perceptual temporal order judgments require an individual to determine the relative timing of two spatially separate events. Here we reveal the brain regions involved with this task. We had participants observe perceptually identical visual stimuli while conducting two different tasks: discriminating temporal order or discriminating spatial properties. By contrasting the functional magnetic resonance imaging signals during these tasks, we were able to isolate regions specifically engaged by each task. Participants observed two briefly presented rectangles. In one task, participants were instructed to report which appeared first, and, in the other, they were requested to report which rectangle was squarer. A potential confound of this study is that the temporal order judgment (TOJ) task required processing of brief events (onsets), whereas the shape task did not require temporal selectivity. To address this, we conducted a second study in which both tasks required discriminating brief events concurrent with the object onsets. The stimuli were similar to the first experiment, except a gray line was briefly superimposed on each rectangle at onset. Participants reported either which rectangle appeared first (TOJ) or which rectangle had a slightly wider gray line (shape). The first study found that the TOJ task resulted in greater bilateral activation of the temporal parietal junction (TPJ). The second revealed TOJ activation in the TPJ of the left hemisphere. This suggests that TPJ activation increases when we need to temporally sequence information. This finding supports the notion that the TPJ may be a crucial component of the “when” pathway.