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International audience; This study investigates the development of landmark and route knowledge in complex wayfinding situations. It focuses on how children (aged 6, 8, and 10 years) and young adults (n = 79) indicate, recognize, and bind landmarks and directions in both verbal and visuo-spatial tasks after learning a virtual route. Performance in these tasks is also related to general verbal and visuo-spatial abilities as assessed by independent standardized tests (attention, working memory, perception of direction, production and comprehension of spatial terms, sentences and stories). The results first show that the quantity and quality of landmarks and directions produced and recognized by participants in both verbal and visuo-spatial tasks increased with age. In addition, an increase with age was observed in participants' selection of decisional landmarks (i.e., landmarks associated with a change of direction), as well as in their capacity to bind landmarks and directions. Our results support the view that children first acquire landmark knowledge, then route knowledge, as shown by their late developing ability to bind knowledge of directions and landmarks. Overall, the quality of verbal and visuo-spatial information in participants' spatial representations was found to vary mostly with their visuo-spatial abilities (attention and perception of directions) and not with their verbal abilities. Interestingly, however, when asked to recognize landmarks encountered during the route, participants show an increasing bias with age toward choosing a related landmark of the same category, regardless of its visual characteristics, i.e., they incorrectly choose the picture of another fountain. The discussion highlights the need for further studies to determine more precisely the role of verbal and visuo-spatial knowledge and the nature of how children learn to represent and memorize routes.

According to grounded cognition, the format of representation of knowledge is sensorimotor. This means that long-term memory shares processing resources with the sensorimotor system. The main objective of this work is to provide new evidence in favour of two claims from the embodied cognition framework: (1) memory is grounded on the sensorimotor system, that is, memory shares processing resources with the sensorimotor system, and (2) memory serves at least in part to support action. For this purpose, the present experiment aimed to show that the action context modulates the motor simulation and, consequently, the memory of manipulable objects. Participants were presented with short phrases comprising the name of a manipulable object, and an action verb (“To take a cup”) or an attentional verb (“To see a cup”). During this phase, they had to put their hands in front of them in the control condition, whereas they had to keep them behind their back in the interfering condition. A cued recall test followed after a short distractive letter-matching task, with the verbs serving as cues. Results showed that memory of the words denoting manipulable objects was impaired by the interfering posture when associated with an action verb, but not when associated with an attentional verb. This suggests that a context which does not favour action interferes with motor simulation and thus decreases the memory of manipulable objects. These results provide strong evidence for a grounded account of memory and language.

International audience; BackgroundFew studies have examined the prevalence and correlates of subsyndromal and syndromal depressive symptoms (SSSD) among older adults with schizophrenia spectrum disorder. In this report, we examined the prevalence of SSSD and their associations with sociodemographic characteristics, clinical characteristics of schizophrenia, comorbidity, psychotropic medications, quality of life, functioning and mental health care utilization in a large, multicenter sample of older adults with schizophrenia spectrum disorder.MethodsData from the Cohort of individuals with Schizophrenia Aged 55 years or more (CSA) were used to examine the prevalence of SSSD, defined using the Center of Epidemiologic Studies Depression (CESD) scale. Clinical characteristics associated with SSSD were explored.ResultsAmong 343 older adults with schizophrenia spectrum disorder, 78.1% had either subsyndromal (30.6%) or syndromal (47.5%) depressive symptoms. SSSD were independently associated with positive and negative symptoms, lower quality of life, non-late-onset psychosis, benzodiazepine use and urbanicity. There were no significant associations of SSSD with other sociodemographic characteristics and psychotropic medications, or with general medical conditions. We found no significant differences in the proportion of participants who were treated with antidepressants between those with syndromal depressive symptoms and those without depression (22.1% vs. 20.0%, p = 0.89). SSSD were not associated with higher mental health care utilization.LimitationsData were cross-sectional and depression was not evaluated with a semi-structured interview.ConclusionSSSD may be highly prevalent and under-assessed and/or undertreated among older adults with schizophrenia spectrum disorder. Our findings should alert clinicians about the need to assess systematically and regularly depression in this vulnerable population.

Planning routes using transportation network maps is a common task that has received little attention in the literature. Here, we present a novel eye-tracking paradigm to investigate psychological processes and mechanisms involved in such a route planning. In the experiment, participants were first presented with an origin and destination pair before we presented them with fictitious public transportation maps. Their task was to find the connecting route that required the minimum number of transfers. Based on participants' gaze behaviour, each trial was split into two phases: (1) the search for origin and destination phase, i.e., the initial phase of the trial until participants gazed at both origin and destination at least once and (2) the route planning and selection phase. Comparisons of other eye-tracking measures between these phases and the time to complete them, which depended on the complexity of the planning task, suggest that these two phases are indeed distinct and supported by different cognitive processes. For example, participants spent more time attending the centre of the map during the initial search phase, before directing their attention to connecting stations, where transitions between lines were possible. Our results provide novel insights into the psychological processes involved in route planning from maps. The findings are discussed in relation to the current theories of route planning.

Anomalous activations of the prefrontal cortex (PFC) and posterior cerebral areas have been reported in previous studies of working memory in schizophrenia. Several interpretations have been reported: e.g., neural inefficiency, the use of different strategies and differences in the functional organization of the cerebral cortex. To better understand these abnormal activations, we investigated the cerebral bases of a working memory component process, namely refreshing (i.e., thinking briefly of a just-activated representation). Fifteen patients with schizophrenia and 15 control subjects participated in this functional magnetic resonance imaging (fMRI) study. Participants were told that whenever they saw a word on the screen, they had to read it silently to themselves (read and repeat conditions), and when they saw a dot, they had to think of the just-previous word (refresh condition). The refresh condition (in comparison with the read condition) was associated with significantly increased activation in the left inferior frontal gyrus and significantly decreased connectivity within the prefrontal cortex and between the prefrontal and parietal cortices in patients with schizophrenia in comparison with control subjects. These results suggest that prefrontal dysfunctions in schizophrenia might be related to a defective ability to initiate (rather than to execute) specific cognitive processes.

International audience; SET is a multifunctional protein, but when present in the cytoplasm, acts as a powerful inhibitor of phosphatase 2A. We previously observed that in CA1 of Down syndrome (DS) patients, the level of SET is increased, and SET is translocated to the cytoplasm and associated with the hyperphosphorylation of tau at ser202/thr205. The presence of SET in the cytoplasm in DS brains may play a role in the progression of the disease. Here, we show that in CA1 of 3-month-old Ts65Dn mice modeling DS, SET level is increased, and SET is translocated to the cytoplasm and associated with tau hyperphosphorylations at ser202/ thr205 and with amyloid precursor protein caspase cleaved as observed in Alzheimer disease brains. Tau hyperphosphorylation at ser356 and activation of other phosphatase 2A targets such as the mammalian target of rapamycin and adenosine monophosphate protein kinases were also observed, suggesting deleterious mechanisms. We propose Ts65Dn mice as a model for therapeutic approaches focused on SET overexpression and its cytoplasmic translocation to slow down disease progression.

International audience; Anorexia nervosa (AN) is classically defined as a condition in which an abnormally low body weight is associated with an intense fear of gaining weight and distorted cognitions regarding weight, shape, and drive for thinness. This article reviews recent evidences from physiology, genetics, epigenetics, and brain imaging which allow to consider AN as an abnormality of reward pathways or an attempt to preserve mental homeostasis. Special emphasis is put on ghrelino-resistance and the importance of orexigenic peptides of the lateral hypothalamus, the gut microbiota and a dysimmune disorder of neuropeptide signaling. Physiological processes, secondary to underlying, and premorbid vulnerability factors—the “pondero-nutritional-feeding basements”- are also discussed.

Although many studies have investigated spatial representation in young adults, little is still known about the processes underlying how they construct spatial models, the nature of these models, and how they develop in children. The originality of this thesis is two-fold: it studies both cognitive and linguistic processes involved in how children (5 to 11 years) and adults construct representation of virtual routes; it also examines individual differences in these processes.The first part of this thesis begins with a chapter that presents the main concepts underlying spatial cognition, as well as some experimental evidence concerning adults’ spatial knowledge and the development of this knowledge during childhood. A second chapter then focuses on the role of language and a third one on the role of working memory in the construction of spatial representations.In order to understand how children construct spatial representation during development, a second part of the thesis presents three experiments investigating the development of landmark and route knowledge. The first two studies show developments in the quality and quantity of knowledge concerning both landmarks (i.e. specific entities encountered along the route) and the route (i.e. the sequential order of actions and landmarks). They also provide evidence supporting the specific role of landmarks associated with changes of direction (“decisional” landmarks) in children and adults. Developmental changes in spatial knowledge were assessed by both verbal and non-verbal measures, suggesting the existence of a unique representation or of two representations that are strongly related. The relation between verbal and non-verbal information in participants’ representations is evidenced by their bias toward choosing a related landmark of the same semantic category, regardless of its visual characteristics. Nevertheless, analyses show that visuo-spatial abilities such as the perception of directions, but not verbal abilities, play a main role in accounting for individual differences. The third study, investigates verbal and visuo-spatial components of working memory, using a dual task paradigm in which participants performed a verbal or spatial interference task while memorizing routes. The results support the idea that representing itineraries mostly involves a spatial mode of encoding in children and a more verbal or mixed encoding in adults.To conclude, this thesis shows a development in children’s capacity to build spatial representations of virtual routes. Although their representation seems to integrate both verbal and non-verbal components, non-verbal abilities appear to be most essential for children. The last part of the thesis discusses the implications of our results for our understanding of the development of spatial cognition in children, as well as future perspectives and conclusions., Si de nombreux travaux ont été consacrés aux représentations spatiales chez le jeune adulte, la nature des modèles spatiaux, les processus qui président à leur construction et la façon dont ils se développent sont encore loin d’être compris. L’originalité de cette thèse tient au fait d’étudier conjointement les composantes cognitives et langagières dans l’acquisition des représentations d’itinéraires virtuels par des enfants (de 5 à 11 ans) et des adultes, ainsi que les différences individuelles liées à des capacités générales variées.Dans une première partie, la thèse présente les principaux concepts de la cognition spatiale issus des travaux menés chez l’adulte ainsi que l’état des connaissances théoriques et empiriques actuelles sur le développement des représentations spatiales chez l’enfant. Un chapitre s’intéresse ensuite au rôle du langage dans la construction des représentations spatiales et un autre à celui de la mémoire de travail.Afin de mieux comprendre le type de représentation qu’un enfant élabore au cours de son développement, une deuxième partie de la thèse présente trois expériences étudiant le développement des connaissances sur les repères et la route. Les deux premières études ont permis d’observer une augmentation qualitative et quantitative de la connaissance des repères, c’est-à-dire des entités spécifiques qui jalonnent un itinéraire, mais également de la connaissance de la succession de ces repères et des directions empruntées. Le rôle particulier des repères situés à un changement de direction est attesté chez l’adulte comme chez l’enfant. L’augmentation de ces connaissances avec l’âge est observée avec des tâches de production et de reconnaissance, aussi bien verbales que non-verbales. Ces résultats suggèrent l’existence d’une seule représentation commune ou de deux formats de représentations fortement reliés. Le lien important entre les informations verbales et non-verbales dans les représentations est attesté par l’observation d’un biais de type sémantique dans la reconnaissance visuelle de repères. Cependant, l’analyse des différences interindividuelles a mis en évidence le rôle de capacités visuo-spatiales telles que la perception des directions, mais pas d’influence des capacités langagières sur la capacité de représentation d’itinéraire. Une troisième étude explore le rôle des composantes verbales et visuo-spatiales de la mémoire de travail dans le développement des représentations spatiales au moyen d’un paradigme de double tâche (verbale ou spatiale) lors de la mémorisation d’itinéraires. L’implication, notamment de la composante spatiale de la mémoire de travail au cours de la mémorisation d’itinéraire, est mise en évidence chez l’enfant. Ce résultat renforce l’idée de la dominance d’une forme de codage visuo-spatial dans le développement de la représentation qui évoluerait au profit de codages plus verbaux ou mixtes.En conclusion, cette thèse montre le développement de la capacité à se représenter un itinéraire au cours de l’enfance, attesté par des tâches de nature et de format variés. Si cette représentation semble impliquer à la fois des composantes verbales et non-verbales, ces dernières semblent être plus importantes chez l’enfant. La dernière partie de la thèse propose une discussion des implications de ces résultats pour le développement de la cognition spatiale chez l’enfant, ainsi que des perspectives pour les recherches futures.

International audience; Cancer involves stressful events. One aspect of cognition that is impacted by stress is episodic autobiographical memory (EAM). EAM is intimately linked to self-representation. Some studies have revealed impairment of EAM in patients with breast cancer in remission. Yet, these studies failed to differentiate between the influence of adjuvant treatments and that of psychosocial factors. We therefore assessed the psychological impact of breast cancer diagnosis on EAM and self-representation profiles prior to any adjuvant treatment. Patients newly diagnosed with breast cancer (n=31) and women without any history of cancer (n=49) were compared on state anxiety, EAM and its emotional characteristics, and self-representations. The most anxious patients retrieved fewer emotional details for memories than the controls, and had lower self-representation scores than the least anxious patients, who had no deficits in emotional detail retrieval. Our results revealed distinct EAM profiles for patients, reflecting two contrasting modes of coping with breast cancer.

Although many studies have investigated spatial representation in young adults, little is still known about the processes underlying how they construct spatial models, the nature of these models, and how they develop in children. The originality of this thesis is two-fold: it studies both cognitive and linguistic processes involved in how children (5 to 11 years) and adults construct representation of virtual routes; it also examines individual differences in these processes. The first part of this thesis begins with a chapter that presents the main concepts underlying spatial cognition, as well as some experimental evidence concerning adults' spatial knowledge and the development of this knowledge during childhood. A second chapter then focuses on the role of language and a third one on the role of working memory in the construction of spatial representations. In order to understand how children construct spatial representation during development, a second part of the thesis presents three experiments investigating the development of landmark and route knowledge. The first two studies show developments in the quality and quantity of knowledge concerning both landmarks (i.e. specific entities encountered along the route) and the route (i.e. the sequential order of actions and landmarks). They also provide evidence supporting the specific role of landmarks associated with changes of direction ("decisional" landmarks) in children and adults. Developmental changes in spatial knowledge were assessed by both verbal and non-verbal measures, suggesting the existence of a unique representation or of two representations that are strongly related. The relation between verbal and non-verbal information in participants' representations is evidenced by their bias toward choosing a related landmark of the same semantic category, regardless of its visual characteristics. Nevertheless, analyses show that visuo-spatial abilities such as the perception of directions, but not verbal abilities, play a main role in accounting for individual differences. The third study, investigates verbal and visuo-spatial components of working memory, using a dual task paradigm in which participants performed a verbal or spatial interference task while memorizing routes. The results support the idea that representing itineraries mostly involves a spatial mode of encoding in children and a more verbal or mixed encoding in adults. To conclude, this thesis shows a development in children's capacity to build spatial representations of virtual routes. Although their representation seems to integrate both verbal and non-verbal components, non-verbal abilities appear to be most essential for children. The last part of the thesis discusses the implications of our results for our understanding of the development of spatial cognition in children, as well as future perspectives and conclusions., Si de nombreux travaux ont été consacrés aux représentations spatiales chez le jeune adulte, la nature des modèles spatiaux, les processus qui président à leur construction et la façon dont ils se développent sont encore loin d'être compris. L'originalité de cette thèse tient au fait d'étudier conjointement les composantes cognitives et langagières dans l'acquisition des représentations d'itinéraires virtuels par des enfants (de 5 à 11 ans) et des adultes, ainsi que les différences individuelles liées à des capacités générales variées. Dans une première partie, la thèse présente les principaux concepts de la cognition spatiale issus des travaux menés chez l'adulte ainsi que l'état des connaissances théoriques et empiriques actuelles sur le développement des représentations spatiales chez l'enfant. Un chapitre s'intéresse ensuite au rôle du langage dans la construction des représentations spatiales et un autre à celui de la mémoire de travail. Afin de mieux comprendre le type de représentation qu'un enfant élabore au cours de son développement, une deuxième partie de la thèse présente trois expériences étudiant le développement des connaissances sur les repères et la route. Les deux premières études ont permis d'observer une augmentation qualitative et quantitative de la connaissance des repères, c'est-à-dire des entités spécifiques qui jalonnent un itinéraire, mais également de la connaissance de la succession de ces repères et des directions empruntées. Le rôle particulier des repères situés à un changement de direction est attesté chez l'adulte comme chez l'enfant. L'augmentation de ces connaissances avec l'âge est observée avec des tâches de production et de reconnaissance, aussi bien verbales que non-verbales. Ces résultats suggèrent l'existence d'une seule représentation commune ou de deux formats de représentations fortement reliés. Le lien important entre les informations verbales et non-verbales dans les représentations est attesté par l'observation d'un biais de type sémantique dans la reconnaissance visuelle de repères. Cependant, l'analyse des différences interindividuelles a mis en évidence le rôle de capacités visuo-spatiales telles que la perception des directions, mais pas d'influence des capacités langagières sur la capacité de représentation d'itinéraire. Une troisième étude explore le rôle des composantes verbales et visuo-spatiales de la mémoire de travail dans le développement des représentations spatiales au moyen d'un paradigme de double tâche lors de la mémorisation d'itinéraires. L'implication, notamment de la composante spatiale de la mémoire de travail au cours de la mémorisation d'itinéraire, est mise en évidence chez l'enfant. Ce résultat renforce l'idée de la dominance d'une forme de codage visuo-spatial dans le développement de la représentation qui évoluerait au profit de codages plus verbaux ou mixtes. En conclusion, cette thèse montre le développement de la capacité à se représenter un itinéraire au cours de l'enfance, attesté par des tâches de nature et de format variés. Si cette représentation semble impliquer à la fois des composantes verbales et non-verbales, ces dernières semblent être plus importantes chez l'enfant. La dernière partie de la thèse propose une discussion des implications de ces résultats pour le développement de la cognition spatiale chez l'enfant, ainsi que des perspectives pour les recherches futures.

International audience; Information that is processed with reference to oneself, i.e. Self-Referential Processing (SRP), is generally associated with better remembering compared to information processed in a condition not related to oneself. This positive effect of the self on subsequent memory performance is called as Self-Reference Effect (SRE). The neural basis of SRE is still poorly understood. The main goal of the present work was thus to highlight brain changes associated with SRE in terms of activity and functional coupling and during both encoding and retrieval so as to assess the relative contribution of both processes to SRE. For this purpose, we used an fMRI event-related self-referential paradigm in 30 healthy young subjects and measured brain activity during both encoding and retrieval of self-relevant information compared to a semantic control condition. We found that SRE was associated with brain changes during the encoding phase only, including both greater activity in the medial prefrontal cortex and hippocampus, and greater functional coupling between these brain regions and the posterior cingulate cortex. These findings highlight the contribution of brain regions involved in both SRP and episodic memory and the relevance of the communication between these regions during the encoding process as the neural substrates of SRE. This is consistent with the idea that SRE reflects a positive effect of the reactivation of self-related memories on the encoding of new information in episodic memory.

International audience; Semantic dementia (SD) is characterized by gradual loss of semantic memory. While episodic autobiographical memory seems relatively preserved, behavioral studies suggest that episodic future thinking is impaired. We used fMRI to measure brain activity in four SD patients (JPL, EP, LL, EG) while they envisioned future events and remembered personal past events. Twelve healthy elders served as controls. Episodic quality, emotion, mental imagery and level of consciousness (via remember/know judgements) were checked at debriefing. We analyzed the future compared to the past for each patient. All patients presented lateral temporal atrophy, but varied in terms of frontal and anterior hippocampal atrophy. Patient JPL presented atrophy in bilateral superior medial frontal gyri and left anterior hippocampus and was unable to engage in episodic future thinking, despite hyperactivations in frontal and occipital regions. Patient EP presented no atrophy in the anterior hippocampus, but atrophy in bilateral superior medial frontal gyrus and had difficulties to engage in episodic future thinking. Patient LL presented atrophy in left anterior hippocampus, but hyperactivated its right counterpart for future compared to past thinking, permitting her to project efficiently in the future in an episodic way. Patient EG presented no atrophy in the superior medial frontal gyri or anterior hippocampi and was able to engage in episodic future thinking. Altogether, patients' future projections differed depending on the severity and localization of their atrophy. The functional integrity of bilateral superior medial frontal gyri and anterior hippocampus appear crucial for episodic future thinking: atrophy of both structures strongly impairs future projection, while integrity of these structures or hyperactivation of residual tissue normalizes episodic future projection.

International audience; Age-related changes in autobiographical memory (AM) recall are characterized by a decline in episodic details, while semantic aspects are spared. This deleterious effect is supposed to be mediated by an inefficient recruitment of executive processes during AM retrieval. To date, contrasting evidence has been reported on the neural underpinning of this decline, and none of the previous studies has directly compared the episodic and semantic aspects of AM in elderly. We asked 20 young and 17 older participants to recall specific and general autobiographical events (i.e., episodic and semantic AM) elicited by personalized cues while recording their brain activity by means of fMRI. At the behavioral level, we confirmed that the richness of episodic AM retrieval is specifically impoverished in aging and that this decline is related to the reduction of executive functions. At the neural level, in both age groups, we showed the recruitment of a large network during episodic AM retrieval encompassing prefrontal, cortical midline and posterior regions, and medial temporal structures, including the hippocampus. This network was very similar, but less extended, during semantic AM retrieval. Nevertheless, a greater activity was evidenced in the dorsal anterior cingulate cortex (dACC) during episodic, compared to semantic AM retrieval in young participants, and a reversed pattern in the elderly. Moreover, activity in dACC during episodic AM retrieval was correlated with inhibition and richness of memories in both groups. Our findings shed light on the direct link between episodic AM retrieval, executive control, and their decline in aging, proposing a possible neuronal signature. They also suggest that increased activity in dACC during semantic AM retrieval in the elderly could be seen as a compensatory mechanism underpinning successful AM performance observed in aging. These results are discussed in the framework of recently proposed models of neural reorganization in aging.

International audience; Use of morphologically related words often helps in selecting among spellings of sounds in French. For instance, final /wa/ may be spelled oi (e.g., envoi “sendoff”), oit (e.g., exploit “exploit”), ois (e.g., siamois, “siamese”), or oie (e.g., joie “joy”). The morphologically complex word exploiter “to exploit”, with a pronounced t, can be used to indicate that the stem exploit is spelled with a silent t. We asked whether 8-year-old children benefited from such cues to learn new spellings. Children read silently stories which included two target nonwords, one presented in an opaque condition and the other in a morphological condition. In the opaque condition, the sentence provided semantic information (e.g., a vensois is a musical instrument) but no morphological information that could justify the spelling of the target word's final sound. Such justification was available in the morphological condition (e.g., the vensoisist plays the vensois instrument, which justifies that vensois includes a final silent s). 30 min after having read the stories, children's orthographic learning was assessed by asking them to choose the correct spelling of each nonword from among three phonologically plausible alternatives (e.g., vensois, vensoit, vensoie). Children chose correct spellings more often in the morphological condition than the opaque condition, even though the root (vensois) had been presented equally often in both conditions. That is, children benefited from information about the spelling of the morphologically complex word to learn the spelling of the stem.

International audience; Autobiographical memory is commonly impaired in Alzheimer's disease (AD). However, little is known about the very recent past which is though highly important in daily life adaptation. In addition, the impact of sleep disturbances, also frequently reported in AD, on the consolidation and retrieval of autobiographical memories remains to be assessed. Using an adaptation of the TEMPau task, we investigated the neural substrates of autobiographical memory for recent events and the potential relationship with sleep in 14 patients with mild AD. On day 1, autobiographical memory was explored across 3 periods: remote (18-30 years), the last two years and the last month. After testing, sleep was recorded using polysomnography. The next day, AD patients benefited a resting state 18FDG-PET scan and a second exploration of autobiographical memory, focusing on the very recent past (today and yesterday). Total recall and episodic recall scores were obtained. In addition, for all events recalled, Remember responses justified by specific factual, spatial and temporal details were measured using the Remember/Know paradigm. Retrieval of autobiographical memories was impaired in AD, but recall of young adulthood and very recent events was relatively better compared to the two intermediate periods. Recall of recent events (experienced the day and the day preceding the assessment) was correlated with brain glucose consumption in the precuneus and retrosplenial cortex, the calcarine region, the angular gyrus and lateral temporal areas. AD patients also provided more Justified Remember responses for events experienced the previous day than for those experienced the day of the assessment. Moreover, Justified Remember responses obtained for events experienced before sleep were positively correlated with the amount of slow-wave sleep. These data provide the first evidence of an association between the ability to retrieve recent autobiographical memories and sleep in mild AD patients.

International audience; Autobiographical memory is commonly impaired in Alzheimer's disease (AD). However, little is known about the very recent past which is though highly important in daily life adaptation. In addition, the impact of sleep disturbances, also frequently reported in AD, on the consolidation and retrieval of autobiographical memories remains to be assessed. Using an adaptation of the TEMPau task, we investigated the neural substrates of autobiographical memory for recent events and the potential relationship with sleep in 14 patients with mild AD. On day 1, autobiographical memory was explored across 3 periods: remote (18-30 years), the last two years and the last month. After testing, sleep was recorded using polysomnography. The next day, AD patients benefited a resting state 18FDG-PET scan and a second exploration of autobiographical memory, focusing on the very recent past (today and yesterday). Total recall and episodic recall scores were obtained. In addition, for all events recalled, Remember responses justified by specific factual, spatial and temporal details were measured using the Remember/Know paradigm. Retrieval of autobiographical memories was impaired in AD, but recall of young adulthood and very recent events was relatively better compared to the two intermediate periods. Recall of recent events (experienced the day and the day preceding the assessment) was correlated with brain glucose consumption in the precuneus and retrosplenial cortex, the calcarine region, the angular gyrus and lateral temporal areas. AD patients also provided more Justified Remember responses for events experienced the previous day than for those experienced the day of the assessment. Moreover, Justified Remember responses obtained for events experienced before sleep were positively correlated with the amount of slow-wave sleep. These data provide the first evidence of an association between the ability to retrieve recent autobiographical memories and sleep in mild AD patients.

International audience; Episodic autobiographical memory (EAM) consists of personal events embedded within a specific spatiotemporal context. Patients with semantic dementia (SD) generally show preserved recent EAMs, but a controversy remains concerning their ability to retrieve remote ones. Only one fMRI study examined remote autobiographical memory in SD through a longitudinal case study (Maguire, Kumaran, Hassabis, & Kopelman, 2010). Here, we propose a cross-sectional study to test the hippocampo-neocortical up-regulation hypothesis, through a multimodal approach (gray matter volume, activation, connectivity analyses), directly comparing recent and remote autobiographical memory retrieval and collecting data to asses phenomelogical re-experiencing. EAM retrieval recruits a distributed network of brain regions, notably the hippocampus which is shown to be atrophied in SD, although some studies report no hippocampal atrophy in SD. Using fMRI, we examined recent and remote EAM retrieval in two SD patients with different profiles of hippocampal atrophy, compared to 12 healthy elders (HE). JPL presented severe bilateral hippocampal atrophy, while EP showed sparing of both hippocampi. Behaviourally, JPL was impaired at retrieving EAMs from both life periods and showed poorer use of visual mental imagery than HE, while EP retrieved memories which were as episodic as those of HE for both periods and relied on greater use of visual mental imagery than HE. Neuroimaging results showed that, for JPL, hyperactivations of the residual hippocampal tissue and of frontal, lateral temporal, occipital and parietal cortices did not efficiently compensate his autobiographical memory deficit. EP however presented hyperactivations in similar neocortical regions which appeared to be more efficient in compensating for atrophy elsewhere, since EP's EAM retrieval was preserved. Functional connectivity analyses focusing on the hippocampus showed how the residual hippocampal activity was connected to other brain areas. For JPL, recent autobiographical retrieval was associated with connectivity between the posterior hippocampus and middle occipital gyrus, while for EP, connectivity was detected between the anterior hippocampus and numerous regions (medial temporal, occipital, temporal, frontal, parietal) for both recent and remote periods. These findings suggest that intensification of hippocampal atrophy in SD strongly affects both recent and remote autobiographical recollection. Up-regulation of neocortical regions and functional hippocampal-neocortical connectivity within the autobiographical network may be insufficient to compensate the lifelong episodic memory deficit for patients with extensive hippocampal atrophy.

EnglishPicture naming is a highly popular task in language production research. In particular, the frequency effect obtained in picture naming is generally considered as the signature of lexical access in speech production. However, it is quite well established that picture naming is very sensitive to the phonetic properties of the word to be produced, imposing some limitations in using this task. In this paper, we look for a frequency effect in the lexical access to picture names, by means of a phoneme-monitoring task. This task requires access to the object name’s phonological representation but not its actual articulation. We found a robust frequency effect. Two additional experiments—visual object identification and semantic categorization—allow us to assume that the locus for the frequency effect is lexical. francaisLa denomination d’images est une procedure privilegiee pour l’etude de la production du langage. En particulier, l’effet de frequence en denomination a ete considere comme la signature de l’acces au lexique mental. Toutefois, en raison de sa nature articulatoire, la reponse de denomination est tres sensible aux proprietes phonetiques du mot a produire, ce qui contraint son utilisation. Dans cet article, nous examinons l’effet de frequence dans l’acces lexical aux noms d’image en utilisant une tâche de detection de phoneme. Cette tâche necessite l’acces a la representation phonologique du nom de l’objet, mais pas son articulation. Nous trouvons un effet robuste de frequence. Deux experiences complementaires –identification d’objet visuel et categorisation semantique – nous permettent de supposer que le locus de l’effet de frequence est lexical.

[This corrects the article on p. 209 in vol. 7, PMID: 26973551.].

[This corrects the article on p. 280 in vol. 8, PMID: 24847236.].