Primary progressive aphasia (PPA) is a neurodegenerative disorder characterized by progressive loss of speech and language. Although speech perception and language comprehension deficits are observed in individuals with PPA, these deficits have been understudied relative to production deficits. Recent work has examined receptive language processing at sublexical, lexical, and semantic levels in PPA; however, systematic investigation of these levels of processing within a single PPA cohort is lacking. The current study sought to fill this gap. Individuals with logopenic, nonfluent, and semantic variants of PPA and healthy, age-matched controls completed minimal pairs syllable discrimination, auditory lexical decision, and picture-word verification tasks to assess sublexical, lexical, and semantic processing. Distinct profiles were observed across PPA variants. Individuals with logopenic variant PPA had impaired performance on auditory lexical decision and picture-word verification tasks, with a trend toward impaired performance on the syllable discrimination task. Individuals with nonfluent and semantic variant PPA had impaired performance only on auditory lexical decision and picture-word verification. Evaluation of the types of errors made on the picture-word verification task (phonological and semantic) provided further insight into levels of deficits across the variants. Overall, the results indicate deficits in receptive processing at the lexical-phonological, lexical-semantic, and semantic levels in logopenic variant PPA, with a trend toward impaired sublexical processing. Deficits were observed at the lexical-semantic and semantic levels in semantic variant PPA, and lexical-phonological deficits were observed in nonfluent PPA, likely reflecting changes both in lexical-phonological processing as well as changes in predictive coding during perception. This study provides a more precise characterization of the linguistic profile of each PPA subtype for speech perception and language comprehension. The constellation of deficits observed in each PPA subtype holds promise for differential diagnosis and for informing models of intervention.

This study explored the role of metacognition in the so-called "age-prospective memory (PM) paradox" by investigating the accuracy of younger and older adults' predictions of their future PM performance in time-based tasks performed across laboratory and naturalistic settings. Metacognitive monitoring was assessed by asking participants to make judgments-of-learning (JOLs) on an item level for both the prospective (remembering that something has to be done) and retrospective (remembering what to do) components of PM. In terms of PM performance, the results for the prospective component revealed an age deficit in the laboratory-based task and an age benefit in the naturalistic task, in line with the age-PM paradox. In terms of metacognition, important age differences were found across settings. In particular, the results pointed to poor resolution of JOLs made by older adults in the laboratory and by younger adults in the naturalistic setting. This suggests that younger and older participants could not discriminate between items they would later hit or miss but did so in different settings. Furthermore, although both age groups exhibited overconfidence in the naturalistic setting, this bias was significantly stronger for the younger adults. This might explain the observed differences in performance. That is, the advantage older adults have in naturalistic tasks may stem from a better ability to predict performance in this setting compared to younger adults, who tend instead to heavily overestimate their capabilities and may therefore not engage in appropriate strategies or planning. These findings speak to the functional relevance of metacognitive monitoring processes for PM performance and suggest considering metacognition as a key factor in explaining the age-PM paradox.

People who look different from oneself are often categorized as homogeneous members of another racial group. We examined whether the relationship between such categorization and the tendency to generalize across outgroup individuals is explained by perceived visual similarity, leading to an all-look-alike misperception. To address this question at the neural level, White participants perceived sequences of White and Black faces while event-related electrocortical activity was recorded. Prior to each face sequence, one specific ingroup or outgroup face was instructed as a cue for receiving unpleasant electric shocks (threat cue), and we were interested in the extent to which such threat effects generalize to other non-instructed faces (safety cues). Face stimuli were presented in adaptor-target pairs, consisting of two ingroup faces or two outgroup faces, which could depict either the same or different identities. Results show less identity processing of outgroup compared to ingroup faces in early visual processing, i.e., N170 repetition suppression was sensitive only to ingroup face identities. Subsequently, as indicated by enhanced Late Positive Potentials to both threat and safety faces, instructed threat generalized stronger across outgroup compared to ingroup faces. These findings and their interaction suggest that the misperception of outgroup homogeneity may be an early precursor to the tendency to generalize threat associations across outgroup individuals.

Despite the need for successful navigation, humans vary greatly in their ability to navigate, and these individual differences may relate to variation in brain structure. While prior research provides support for a correlation between hippocampal volume and navigation ability in both navigation experts and in older individuals, this relationship is under scrutiny for healthy, young adults. We assessed 99 healthy young adults' ability to navigate in a virtual, desktop maze and correlated their performance with total hippocampal gray matter volume. For a subset of these individuals, we further segmented the medial temporal lobe-including regions of the hippocampus-into anatomically-distinct subregions to uniquely examine the association between volumes of hippocampal subfields and navigation. Given the need to distinguish between similar-looking maze hallways and partially overlapping routes, young adults with stronger pattern separation ability may perform better in this task. Thus, we theorized that successful navigation would positively correlate with hippocampal CA3 and dentate gyrus (DG) subfield volumes due to these regions' role in pattern separation. CA1 and entorhinal cortex (ERC) are both associated with rodent spatial memory, too, suggesting a possible relationship between their volumes and navigation performance. Consistent with our hypotheses, we observed a positive relationship between volumes of hippocampal subfields and wayfinding accuracy, while ERC and parahippocampal cortex volumes correlated with navigation efficiency. However, when analyzing total hippocampal volume, a nuanced interpretation is warranted. We found evidence of Simpson's Paradox, where total hippocampal volume and navigation accuracy displayed no correlation in males, a negative correlation in females, yet a positive correlation when considering the full sample of males and females combined. Furthermore, no significant relationship was observed between total hippocampal volume and path efficiency. Given these findings, we urge caution in interpreting the results because these associations differ by analysis techniques (including voxel-based morphometry), after sex stratification, and with anterior and posterior hippocampal subdivisions. Overall, this study enhances our understanding of the relationship between brain volume and navigation ability for young adults but also emphasizes the need for methodological consistency across studies with respect to boundary definitions, neuroimaging techniques, statistical methods, and factors that give rise to individual differences.

While considerable knowledge has been acquired concerning the involvement of the parietal cortex in horizontal visuo-spatial attention, the understanding of its specific contribution to the vertical dimension remains limited. Here we present the exceptional case of a patient, who suffered from two consecutive ischemic strokes at the same location within the left and right Middle Cerebral Artery (MCA) territory, involving the superior parietal lobule, the supramarginal gyrus, and the angular gyrus. While the first left-hemispheric stroke led to a right-sided neglect, the consecutive stroke in the right hemisphere led to a left-sided neglect. In both cases, the horizontal visuo-spatial attentional bias resolved after a short time period. However, after the second stroke, the patient displayed a notable manifestation of vertical neglect for the right and the left lower visual space, as shown by means of a neuropsychological assessment with the Sensitive Neglect Test. Furthermore, video-oculography during Free Visual Exploration (FVE), comparing the patient's exploration behaviour against twenty age-matched healthy controls, confirmed the significant visuo-spatial attentional deficits for the lower visual space. In conclusion, the present case study illustrates that the parietal cortex controls visuo-spatial attention deployment towards the contralateral and, more prominently, towards the lower visual space. Therefore, the clinical evaluation of neglect symptoms should also take the vertical dimension into account.

A major puzzle in the visual word recognition literature is how the human brain deals with complex words (e.g., presuppose). Prior work has shown that a multi-stage process is involved, starting with the early, form-based decomposition stage where a word is broken down into smaller pieces called morphemes {pre-}+{suppose} and ending with the recombination stages where the pieces are put back together to access the word's full meaning. However, most neurolinguistic studies have focused on the first stage, and/or on derivational morphology, which inherently carries both syntactic and semantic information, and this research has overwhelmingly investigated Indo-European languages. Here, we investigate visual word recognition of Tagalog complex words, focusing on inflectional prefixes which allows us to zero in on the contribution of syntactic information during the recombination stage, where both syntactic and semantic information are expected to be analyzed. Using MEG, we replicate previous findings implicating the left fusiform gyrus in segmenting complex words into pieces. We also show that the recombination stages, where the morphological pieces are put back together, activate the left posterior temporal lobe and left orbitofrontal cortex. Although our results support a multi-stage comprehension model of complex words and confirm that these distinct stages are associated with distinct spatiotemporal profiles, we also observed some spatiotemporal differences compared to previous studies on derivational morphology. For the first time, we show that inflected words activate the same core processing profile as derived words in the early (decomposition) stage, while later (recombination) stages of morphological processing point to an earlier and faster recombination of inflected words.

Previous studies indicated that the sense of body ownership (i.e., the feeling that our body parts belong to us; SBO) can be experimentally modulated in humans. Here, we focused on SBO from an across-species perspective, by investigating whether similar bottom-up and top-down constraints that consent to build SBO in humans also operate to build it in monkeys. To this aim, one monkey and a cohort of humans (N = 20) performed a paradigm combining the well-known rubber hand illusion (RHI), able to induce a fake hand embodiment, and a hand-identification reaching task, borrowed from the clinical evaluation of patients with SBO disorders. This task consisted of reaching one's own hand with the other, while presenting a fake hand in different conditions controlling for bottom-up (synchronicity of the visuo-tactile stimulation) and top-down (congruency of the fake hand position relative to the monkey's body) SBO constraints. Spatiotemporal kinematic features of such self-directed movements were measured. Our results show that, when the monkey aimed at the own hand, the trajectory of self-directed movements was attracted by the position of the hand believed to be one's own (i.e., the fake hand), as in humans. Interestingly, such an effect was present only when both bottom-up and top-down constraints were met. Moreover, in the monkey, besides displacement of movement trajectory, also other kinematic parameters (velocity peak, deceleration phase) showed sensitivity to the embodiment effect. Overall, if replicated in a larger sample of monkeys, these results should support the view that human and non-human primates share similar body representation constraints and that they are able to modulate the motor behavior in both species.

Post-stroke motor deficits often disrupt the voluntary control of body movements, leading to abnormal feelings. Among these, alterations in the sense of agency (SoA), the feeling of controlling one's movement, are notable because SoA facilitates actions. However, whether patients with more severe motor deficits experience poorer SoA and SoA's clinical impact on motor activity remain unclear. To address these questions, this longitudinal study quantified SoA in 156 post-stroke patients through factor analyses with multiple question items to differentiate SoA from potentially confounding discomfort. Structural equation modeling revealed that SoA decreased significantly with upper-limb motor deficit severity and that reduced SoA correlated significantly with decreased paretic upper-limb use. Notably, this effect persisted after controlling for motor deficit severity, suggesting a direct clinical impact of SoA on motor activity. Further, improvements in SoA were significantly associated with increased upper-limb use in patients with moderate or severe motor deficits, emphasizing the role of SoA in maintaining or increasing paretic upper-limb activity. These findings highlight the importance of rehabilitation treatments that consider patients' subjective experiences, particularly agency attribution.

Extensive research has demonstrated that visual and motor cortices can simultaneously represent multiple observed actions. This ability undoubtedly constitutes a crucial ingredient for the understanding of complex visual scenes involving different agents. However, it is still unclear how these distinct representations are integrated into coherent and meaningful percepts. In line with studies of perceptual binding, we hypothesized that similar movements would be more easily integrated. To test this hypothesis, we developed an EEG frequency tagging experiment in which two hand movements were displayed simultaneously at two different presentation rates. Crucially, the degree of similarity between the two movements varied along two dimensions, namely action identity (i.e., same or different performed movement), and agent identity (i.e., one agent performing a bimanual movement, or two agents moving each one hand). Contrary to our predictions, we found a larger intermodulation oscillatory component, indexing the integrated processing of the two individual movements, when they were less similar. We propose that integration-by-dissimilarity might serve as a top-down process to solve conflict caused by incongruent movements, thus contributing to the global understanding of distinct moving individuals in a complex social scene.

Adolescence is a critical period where individuals build their identity and consolidate how they interact with others. However, for adolescents with autism spectrum disorder (ASD), the development of identity and social bounds is at stake. These challenges with the development of identity and social bonds could be linked to difficulties in autobiographical memory (AM), whether recalling past events (past episodic memory; past EM) or imagining future scenarios (episodic future thinking; EFT). To date, developmental patterns of AM over time remain poorly understood in ASD. Eleven adolescents with ASD or typical development (TD) completed an assessment of past EM and EFT once per year for three years. Preliminary results show that past EM becomes more detailed over the years for adolescents with ASD, while there is no change for TD adolescents. Interestingly, only the content elements of the narrated events are increasing, not the context elements. Furthermore, EFT evolves in the TD group but remains stable in the ASD group. This first multi-case longitudinal study of AM needs to be replicated with more participants, but it seems to indicate a heterogeneous evolution of AM in ASD. For future studies, these results will lead us to explore the hypothesis of developmental delay and the factors influencing AM development in ASD. Finally, understanding these developmental pathways highlights the importance of personalized therapeutic approaches to support social integration, identity construction, and future projects for adolescents with ASD.

Emotion-related impulsivity (ERI) describes the trait-like tendency toward poor self-control when experiencing strong emotions. ERI has been shown to be elevated across psychiatric disorders and predictive of the onset and worsening of psychiatric syndromes. Recent work has correlated ERI scores with the region-level neuroanatomical properties of the orbitofrontal cortex (OFC), but not posteromedial cortex (PMC). Informed by a growing body of research indicating that examining the morphology of specific cortical folds (sulci) can produce unique insights into behavioral outcomes, the present study modeled the association between ERI and the morphology of sulci within OFC and PMC, which is a finer scale than previously conducted.

Diagnosis of dyslexia often occurs in late schooling years, leading to academic and psychological challenges. Furthermore, diagnosis is time-consuming, costly, and reliant on arbitrary cutoffs. On the other hand, automated algorithms hold great potential in medical and psychological diagnostics. The aim of the present study was to develop a machine learning tool for the detection of dyslexia in children based on the intrinsic connectivity patterns of different brain networks underlying perception and attention. Here, 117 children (8-12 years old; 58 females; 52 typical readers; TR and 65 children with dyslexia) completed cognitive and reading assessments and underwent 10 min of resting-state fMRI. Functional connectivity coefficients between 264 brain regions were used as features for machine learning. Different supervised algorithms were employed for classification of children with and without dyslexia. A classifier trained on dorsal attention network features exhibited the highest performance (accuracy .79, sensitivity .92, specificity .64). Auditory, visual, and fronto-parietal network-based classification showed intermediate accuracy levels (70-75%). These results highlight significant neurobiological differences in brain networks associated with visual attention between TR and children with dyslexia. Distinct neural integration patterns can differentiate dyslexia from typical development, which may be utilized in the future as a biomarker for the presence and/or severity of dyslexia.

Recent historical research has shown that the large complex of research conducted by Aleksandr Luria on aphasia in brain-damaged soldiers during the Second World War was already started at the end of the 1920s, under the theoretical influence of Lev Vygotsky and the results of his clinical studies. The first written document of Luria's interest in neuropsychological investigation is the abstract of a conference held on November 27, 1932, a text published in Russian in 1933 and never reprinted, and here translated for the first time into a Western language.

The primary aim of the current study was to determine whether adults who stutter (AWS) present with anomalous periodic beta (β) rhythms when compared to typically fluent adults in the eyes-open resting state. A second aim was to determine whether lower β power in the RS is related to a measure of β event-related desynchronization (ERD) during syllable sequence execution.

The neurological process of mirror generalization in memory, also known as mirror symmetrization, presents a real dilemma for typically developing 5- to 6-year-olds when learning to write characters (digits and letters). Should they write the digit 3 oriented to the left, that is correctly, or to the right, which leads to its mirror image ε? It has been anecdotally suggested that boys are more prone to mirror-writing than girls, but there is no scientific evidence for this idea. The present article gathers data from 691 children in the upper section of the French école maternelle (age between 5 and 6 ½), who each wrote the digits 0 to 9 four times under dictation and not necessarily in their natural order. Both simple and complex (mixed-effects linear regression) statistical comparisons on the percentages of digit reversal, show a substantial difference: girls produce more mirror reversals than boys. And yet the reversal curves as a function of the digits are quite similar between the two sexes (r = .97). It has been proposed that mirror reversal of characters results from the left orientation of some of them (e.g., 3, 7, J, Z), that is, in an orientation contrary to the direction of writing in our Western cultures. The present investigation shows that (1) this character orientation hypothesis (choosing to write characters in the same orientation as sentence writing) better explains reversals than the counterclockwise hypothesis (children are trained to draw circles counter-clockwise to prepare for attached cursive writing); (2) the study of the stability of reversals additionally supports the explanation of mirror writing by the left orientation of the digits (1, 2, 3, 7 and, less obviously, 9); but (3) neither of the preceding findings (left-right orientation and stability) provided a convincing explanation for the aforementioned gender difference.

The study of the links between episodic memory (memory of personal experiences) and semantic memory (memory of general knowledge about the world, others, and oneself) has played a significant role in psychology and neuroscience research for several decades. The way memories lose specificity and become semantized over time, and how these two major memory systems interact to represent the individual in the social world and allow to project themselves into the future, are particularly fascinating themes in understanding the mechanisms of autobiographical memory. Numerous studies rely on various memory pathologies, primarily amnesic syndromes but also other disorders where memory impairment is not the main symptom, such as autism spectrum disorders. The thesis we support in this opinion paper is that the process of semantization is not limited to the individual system of consciousness alone, at the root of individual memories, but presupposes cooperation between three types of systems: the central nervous system, the individual system of consciousness and the social system (society). The conceptual tools favored by historians and sociologists complement those of psychologists and neuroscientists, allowing for an original elaboration of this construction of human memory, at the interfaces of individual, collective, and social memories. Based on pioneering works in the social sciences and cognitive neuroscience, we illustrated our position with longitudinal studies conducted in the framework of the "Programme 13-Novembre", established following the attacks of November 13, 2015, in Paris and its surrounding suburbs. Using this example, and after recalling the theoretical origins of the process of memory semantization in neuropsychology, this article proposes a framework for analyzing the cognitive and social processes that lead to the semantization of memories in individuals, within groups of various sizes, and in society as a whole.

Recurring utterances (RUs) are a distinct language symptom observed in severe aphasia, known to be associated with global or Broca's aphasia, though their neural basis remains unclear. We present a case of RU induced by selective left frontal suppression using a novel technique named the super-selective Wada test (ssWada), which involves temporary anesthetization of specific brain regions through super-selective catheterization of cerebral arteries. This method allows for precise simulation of localized brain dysfunction. We applied this technique on a 49-year-old right-handed man with drug-resistant epilepsy as a preoperative examination. Propofol administration to the superior branch of the left middle cerebral artery (MCA), supplying the pars triangularis, pars opercularis, middle frontal gyrus, and part of the precentral gyrus, induced Broca's aphasia with RUs. The RU content was the phrase uttered at anesthesia administration. Notably, the anesthetic did not affect the temporal language area or basal ganglia. The patient showed minimal awareness of his abnormal speech despite preserved receptive language function and memory, aligning with previous observations of anosognosia in patients with RU. Contrastingly, anesthetic infusion into the inferior branch of the left MCA resulted in mixed aphasia, while right MCA infusion induced no language impairments. This case demonstrates that RUs can arise without deficits in the posterior language area or basal ganglia. It illustrates the potential of ssWada in investigating neural substrates of neuropsychological symptoms through temporary, localized brain disruption. This approach offers novel insights into brain-behavior relationships in language processing and cognition.

Previous research has focused on how different environments modulate fear learning and the accompanying prioritization of acquired threat cues in sensory cortices. Here, we focus on the other side of the coin and show how the acquisition of threat relevance influences the sensory processing of the environment and an associated context cue. Thereby, we observed that spatial suppression surrounding the focus of threat relevant cues extended by threat learning. By recording frequency-tagged steady-state visual evoked fields (ssVEFs) from 35 healthy participants using Magnetoencephalography (MEG), we replicate earlier findings that centrally presented acquired threat-relevant cues (CS+) evoke greater ssVEF responses, whereas visuocortical engagement during the processing of threat-irrelevant cues (CS-) is inhibited. Critically, as predicted by early computational models of threat learning such as the Rescorla-Wagner model, ssVEF responses to an inter-trial peripheral background flicker (context cue), when no CS was shown, increased linearly during learning. In contrast, visuocortical engagement in the early-tier visual cortex during the processing of the background flicker was strongly reduced during CS presentation in the last learning block. This effect was observed during maximal CS+ and CS- discrimination. However, in more anterior ventral visual cortex, the inhibition of oscillatory responses of the context cue occurred only during CS + trials, whereas during CS- trials, background ssVEF responses were increased. These results are in line with the notion that attentional resources are reallocated flexibly between cues of different threat relevance and that the spatial extension of center surround neuronal competition can be modulated by threat learning.

Closing-in behavior (CIB) is characterized by the placement of the graphic copy near (Near CIB) or even on the top of (Overlap CIB) the stimulus to be reproduced. Although CIB has received little attention in the literature, Sergio Della Sala and colleagues made important contributions to the understanding of the phenomenon. They noted that CIB is often observed in Alzheimer's Disease but is also present in other forms of dementia and mild cognitive impairment and stroke; they argued that CIB may reflect a deficit in executive function, rather than working memory, and that the phenomenon occurs more frequently in dual task conditions. Importantly, they demonstrated that CIB may not be specific to copying but may instead reflect a general deficit in decoupling movement location from the focus of attention. In the present study, we explored these observations in a mixed sample of 106 participants (AD n = 37, frontal stroke n = 25, other forms of dementia n = 24, and normal controls n = 20). First, we confirmed that CIB is equally common in AD, other forms of dementia and frontal stroke. Second, we confirmed the association between CIB and executive function deficits. Third, we showed that individuals with CIB are more likely to exhibit the phenomenon in dual task situations, in which line-drawing is associated with an unrelated secondary task (tapping, counting, or counting backward). The present work supports and extends the contributions of Della Sala and colleagues demonstrating that CIB is enhanced when the general attentional load of the task increases.

An individual's inability to control the movements of their own hand is known as the Anarchic Hand Syndrome. The hand may perform apparently purposeful actions but acts as if it has a will of its own. Although the syndrome was first described over a century ago, the nature of the condition remains, for the most part, obscure, in particular in terms of the definition of the main symptoms and the underlying neural networks. The present study compares the results from in-depth assessments, made at repeated intervals (2, 4 and 7 months from the lesion onset) of the anarchic hand symptoms in three patients suffering from various different forms of brain damage. An investigation of direct grey matter damage and structural connectivity allowed us to compare the grey matter lesions and white matter disconnections in the three patients. A "core" characteristic relating to anarchic hand symptoms was identified, involving, in particular, both apparently purposeful movements (i.e., magnetic apraxia, grasping, bimanual incoordination, disorders in manual dexterity and action sequencing) and non-purposeful movements (i.e., levitation, synkinesis and mirror movements). Furthermore, ideomotor apraxia may also be associated with this syndrome. No overlapping areas of grey matter lesions were found in the three patients. In contrast, a pattern of common white matter disconnections was found, which involves inter-hemispheric disconnections (via corpus callosum), the long intra-hemispheric tracts (via SLF, IFOF and Arcuate) and the descendent tracts (corticospinal tract). These results are discussed in terms of awareness of motor intention.

Pupil size is modulated by various cognitive factors such as attention, working memory, mental imagery, and subjective perception. Previous studies examining cognitive effects on pupil size mainly focused on inducing or enhancing a subjective experience of brightness or darkness (for example by asking participants to attend to/memorize a bright or dark stimulus), and then showing that this affects pupil size. Surprisingly, the inverse has never been done; that is, it is still unknown what happens when a subjective experience of brightness or darkness is eliminated or strongly reduced even though bright or dark stimuli are physically present. Here, we aim to answer this question by using perceptual fading, a phenomenon where a visual stimulus gradually fades from visual awareness despite its continuous presentation. The study contains two blocks: Fading and Non-Fading. In the Fading block, participants were presented with black and white patches with a fuzzy outline that were presented at the same location throughout the block, thus inducing strong perceptual fading. In contrast, in the Non-Fading block, the patches switched sides on each trial, thus preventing perceptual fading. Participants covertly attended to one of the two patches, indicated by a cue, and reported the offset of one of a set of circles that are displayed on top. We hypothesized that pupil size will be modulated by covert visual attention in the Non-Fading block, but that this effect will not (or to a lesser extent) arise in the Fading block. We found that covert visual attention to bright/dark does modulate pupil size even during perceptual fading (Fading block), but to a lesser extent than when the perceptual experience of brightness/darkness is preserved (Non-Fading block). This implies that pupil size is always modulated by covert attention, but that the effect decreases as subjective experience of brightness or darkness decreases. In broader terms, this suggests that cognitive modulations of pupil size reflect a mixture of high-level and lower-level visual processing.

The brain builds and maintains internal models and uses them to make predictions. When predictions are violated, the current model can either be updated or replaced by a new model. The latter is accompanied by pupil dilation responses (PDRs) related to locus coeruleus activity/norepinephrine release (LC-NE). Following earlier research, we investigated PDRs associated with transitions between regular and random patterns of tones in auditory sequences. We presented these sequences to participants and instructed them to find gaps (to maintain attention). Transitions from regular to random patterns induced PDRs, suggesting that an internal model attuned to the regular pattern is reset. Transitions from one regular pattern to another regular pattern also induced PDRs, suggesting that they also led to a model reset. In contrast, transitions from random patterns to regular patterns did not induce PDRs, suggesting a gradual update of model parameters. We modelled these findings, using pupil response functions to show how ongoing PDRs and pupil event rates were sensitive to the trial-by-trial changes in the information content of the auditory sequences. Expanding on previous research, we suggest that PDRs-as biomarkers for LC-NE activation-may indicate the extent of prediction violations.

The synergy between cognitive theory and neuropsychology is a hallmark of Sergio Della Sala's research, of his 25 years as editor of Cortex, and of over 40 years of a Della Sala-Logie research collaboration. This short article highlights some of that completed and ongoing collaborative research focused on the cognition of memory in the healthy, ageing, and impaired brain.

There are substantial differences in the capacity of people to have imagined visual experiences, ranging from a lifelong inability (Congenital Aphantasia) to people who report having imagined experiences that are as vivid as actually seeing (Hyper-Phantasia). While Congenital Aphantasia has typically been framed as a cognitive deficit, it is possible that a weak or absent ability to have imagined visual sensations is balanced by a heightened resistance to intrusive thoughts - which are experienced as an imagined sensation. Here, we report on a direct test of that proposition. We asked people to either imagine, or to try not to imagine having a range of audio and visual experiences while we recorded their brain activity with electroencephalography (EEG). Ratings describing the subjective vividness of different people's voluntary visualisations predicted if they would also report having involuntary visualisations - such as an imagined experience of seeing a pink elephant when they were asked not to. Both the prevalence of different people's involuntary visualisations and the typical vividness of their visualisations could be predicted by neural correlates of disinhibition, working memory, and neural feedback. Our data suggest that the propensity of people to have involuntary visual experiences can scale with the subjective intensity of their typical experiences of visualisation.

Attention to faces and eye contact are key behaviors for establishing social bonds in humans. In Autism Spectrum Disorders (ASD), a disturbance in neurodevelopment, impaired face processing and gaze avoidance are key clinical features for ASD diagnosis. The biological alterations underlying these impairments are not yet clearly established. Using high-density electroencephalography coupled with multi-variate pattern classification and group blind source separation methods we searched for face- and-face components-related neural signals that could best discriminate visual processing of neurotypical subjects (N = 38) from ASD participants (N = 27). We isolated a face-specific neural signal in the superior temporal sulcus peaking at 240 msec after face-stimulus onset. A machine learning algorithm applied on the extracted neural component reached 74% decoding accuracy at the same latencies, discriminating the neurotypical population from ASD subjects in whom this signal was weak. By manipulating attention on different parts of the face, we also found that the power of the evoked signal in neurotypical subjects varied depending on the region observed: it was strong when the eye region fell on the fovea to decrease on regions further away and outside the stimulus face. Such face and face-components selective neural modulations were not found in ASD, although they did show typical early face-related P100 and N170 signals. These results show that specialized cortical mechanisms for face perception show higher responses for eyes when attention is focused on gaze and that these mechanisms may be particularly affected in autism spectrum disorders.

This study investigates the impact of vision on the maintenance of hand representation in the implicit body model, particularly focusing on congenitally blind individuals. To address this, we performed a hand landmark localization task on blind individuals who lacked visual experience of their bodies and compared their performance to normally sighted and normally sighted but blindfolded participants. Through measurements of finger lengths, hand width, and shape index, we demonstrate that blind participants exhibit significantly greater distortions in their hand representation compared to sighted and blindfolded controls. Notably, blind individuals displayed a marked overestimation of hand width and an underestimation of finger lengths, particularly in digits D2, D3, and D4. Surprisingly, blind subjects with partial vision displayed more severe distortions than those with no residual vision. Furthermore, our findings reveal that late-blind participants exhibit similar levels of distortion as congenitally blind individuals, suggesting an extended period of susceptibility to the lack of visual input in shaping body representations. The Reverse Distortion (RD) hypothesis provides a plausible explanation for these distortions, suggesting that compensatory mechanisms occur within the body model to counteract the anisotropic cortical representations. Our results support this hypothesis: blind individuals have expanded cortical representations processing tactile information, so this could lead to more pronounced distortions in their hand representation of the body model. This underscores the importance of visual input in modulating body representations. Overall, our study highlights the malleability of body representations and the intricate interplay between sensory inputs and cortical processing in shaping the implicit body model.

Traditional systems consolidation theories of memory suggest that the role of the hippocampus in maintaining memory representations diminishes over time, with learned information eventually becoming fully independent of the hippocampus. Knowledge of collocations in one's native (L1) language are acquired during development and are solidly acquired by adulthood. Remote semantic knowledge of collocations might therefore be expected to be resistant to hippocampal pathology. Patients with hippocampal damage and severe anterograde amnesia completed two tasks testing English collocation knowledge originally designed for use with English language learners. Patients with hippocampal damage demonstrated impairments in recognition of common English collocations, despite a lifetime of language experience (including postsecondary education) prior to sustaining this damage. These results suggest the hippocampus contributes to the long-term maintenance of linguistic representations and provides a challenge to traditional consolidation views of memory and an extension of newer theories to include a role for the hippocampus in maintaining semantic memory.