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Perini G.,CNRS Laboratory for the Study of Learning and Development
Alzheimer Disease and Associated Disorders | Year: 2016

Misidentification delusions (MDs) are considered relatively rare psychopathologic phenomena that may occur within the context of psychiatric or neurological conditions. The purpose of this study was to assess the prevalence of MD in different types of dementia, correlate the presence of MD with demographic and clinical variables, and validate a specific questionnaire. We examined 146 subjects with Alzheimer disease, 21 with Lewy body dementia, 6 with frontotemporal dementia, and 13 with vascular dementia (subcortical type), who were consecutively enrolled in the study from 2 Memory Clinics. Patients had a mean age of 78.7±6.4 years and an Mini-Mental State Examination average score of 16.9±6.1. The Neuropsychiatric Inventory delusion subscale and a new Misidentification Delusion Questionnaire aimed at specific assessment of 11 delusional misidentification syndromes were administrated to the caregivers. On the basis of the Neuropsychiatric Inventory, MDs were present in 33.3% of the subjects, whereas according to the Misidentification Delusion Questionnaire they were present in 36.0% of the subjects. Specifically, 34.2% of Alzheimer disease, 52.4% of Lewy body dementia, and 46.1% of vascular dementia patients experienced at least 1 MD. None of the patients with frontotemporal dementia developed MD. The most frequent MD was house misidentification, followed by splitting of people and reduplicative paramnesia. Our self-administered questionnaire proved to be an accurate and specific tool for the detection of MD. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved Source

Souchay C.,CNRS Laboratory for the Study of Learning and Development | Wojcik D.Z.,University of Leeds | Williams H.L.,VA | Crathern S.,University of Leeds | Clarke P.,University of Leeds
Cortex | Year: 2013

Introduction: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder primarily affecting social interaction and communication. Recently, there has been interest in whether people with ASD also show memory deficits as a result of abnormal brain development. However, at least in adolescents with ASD, the recollection component of episodic memory has rarely been explored. This paper is an evaluation of recollection in three different experiments in adolescents with ASD, using both objective (source discrimination) and subjective methods (Remember-Know judgments). Methods: Three experiments were designed to measure different aspects of contextual information: sensory/perceptual information (Experiment 1), temporal information (Experiment 2) and spatial information (Experiment 3). To measure objective and subjective recollection, for all three experiments, all participants were presented with information to learn in a specific context. At the recognition stage, they were asked whether they remembered the information or just knew the information was there (R/K response, subjective method). To assess the quality of these subjective judgments, participants justified their Remember responses using the contextual information. After the recognition task, to assess source memory (objective measure), all items presented at encoding were represented and participants have to recall the source for all these items. Results: All three experiments showed that adolescents with ASD could correctly recall source information. However, in the first experiment adolescents with ASD gave significantly fewer Remember responses than controls. Conclusions: These findings point to a specific and subtle recollection impairment in adolescents with ASD, at least when subjective methods are used. We discuss how these might relate to differences in the self and to the brain abnormalities in ASD. © 2012 Elsevier Ltd. Source

Souchay C.,CNRS Laboratory for the Study of Learning and Development
European Journal of Human Genetics | Year: 2015

Learning disabilities (LDs) are a clinically and genetically heterogeneous group of diseases. Array-CGH and high-throughput sequencing have dramatically expanded the number of genes implicated in isolated intellectual disabilities and LDs, highlighting the implication of neuron-specific post-mitotic transcription factors and synaptic proteins as candidate genes. We report a unique family diagnosed with autosomal dominant learning disability and a 6p21 microdeletion segregating in three patients. The 870 kb microdeletion encompassed the brain-expressed gene LRFN2, which encodes for a synaptic cell adhesion molecule. Neuropsychological assessment identified selective working memory deficits, with borderline intellectual functioning. Further investigations identified a defect in executive function, and auditory-verbal processes. These data were consistent with brain MRI and FDG-PET functional brain imaging, which, when compared with controls, revealed abnormal brain volume and hypometabolism of gray matter structures implicated in working memory. We performed electron microscopy immunogold labeling demonstrating the localization of LRFN2 at synapses of cerebellar and hippocampal rat neurons, often associated with the NR1 subunit of N-methyl-D-aspartate receptors (NMDARs). Altogether, the combined approaches imply a role for LRFN2 in LD, specifically for working memory processes and executive function. In conclusion, the identification of familial cases of clinically homogeneous endophenotypes of LD might help in both the management of patients and genetic counseling for families.European Journal of Human Genetics advance online publication, 21 October 2015; doi:10.1038/ejhg.2015.221. © 2015 Macmillan Publishers Limited Source

Moulin C.J.A.,CNRS Laboratory for the Study of Learning and Development
Cortex | Year: 2013

Recollective confabulation (RC) is encountered as a conviction that a present moment is a repetition of one experienced previously, combined with the retrieval of confabulated specifics to support that assertion. It is often described as persistent déjà vu by family members and caregivers. On formal testing, patients with RC tend to produce a very high level of false positive errors. In this paper, a new case series of 11 people with dementia or mild cognitive impairment (MCI) and with déjà vu-like experiences is presented. In two experiments the nature of the recognition memory deficit is explored. The results from these two experiments suggest - contrary to our hypothesis in earlier published case reports - that recollection mechanisms are relatively spared in this group, and that patients experience familiarity for non-presented items. The RC patients tended to be overconfident in their assessment of recognition memory, and produce inaccurate assessments of their performance. These findings are discussed with reference to delusions more generally, and point to a combined memory and metacognitive deficit, possibly arising from damage to temporal and right frontal regions. It is proposed that RC arises from a metacognitive error; an attempt to justify inappropriate feelings of familiarity which leads to false recognition. © 2013. Source

Camos V.,University of Fribourg | Mora G.,CNRS Laboratory for the Study of Learning and Development | Barrouillet P.,University of Geneva
Quarterly Journal of Experimental Psychology | Year: 2013

The aim of our study was to test the hypothesis that two systems are involved in verbal working memory; one is specifically dedicated to the maintenance of phonological representations through verbal rehearsal while the other would maintain multimodal representations through attentional refreshing. This theoretical framework predicts that phonologically related phenomena such as the phonological similarity effect (PSE) should occur when the domain-specific system is involved in maintenance, but should disappear when concurrent articulation hinders its use. Impeding maintenance in the domain-general system by a concurrent attentional demand should impair recall performance without affecting PSE. In three experiments, we manipulated the concurrent articulation and the attentional demand induced by the processing component of complex span tasks in which participants had to maintain lists of either similar or dissimilar words. Confirming our predictions, PSE affected recall performance in complex span tasks. Although both the attentional demand and the articulatory requirement of the concurrent task impaired recall, only the induction of an articulatory suppression during maintenance made the PSE disappear. These results suggest a duality in the systems devoted to verbal maintenance in the short term, constraining models of working memory. © 2013 The Experimental Psychology Society. Source

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