Similar or Different? The Role of the Ventrolateral Prefrontal Cortex in Similarity Detection

Patients with frontal lobe syndrome can exhibit two types of abnormal behaviour when asked to place a banana and an orange in a single category: some patients categorize them at a concrete level (e.g., “both have peel”), while others continue to look for differences between these objects (e.g., “one is yellow, the other is orange”). These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC). We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients. We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC

Caractéristiques des malformations artérioveineuses cérébrales révélées par des crises d'épilepsie

PARIS7-Xavier Bichat (751182101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Invalidation of Parkinson's disease diagnosis after years of follow-up based on clinical, radiological and neurophysiological examination

International audienceIntroduction : Diagnosis of Parkinson's disease (PD) is mainly based on clinical features. Accurate neurological examination is required but dopamine transporter (DaT) single photon emission computed tomography (SPECT) could be perfomed to support the diagnosis in ambiguous cases. The aim of this work is to describe the characteristics of patients with a prolonged PD misdiagnosis.Methods : We collected data from 24 patients initially diagnosed with PD who had an atypical long-term evolution. We analyzed demographic and clinical characteristics and antiparkinsonian drugs medication. Brain MRI, DaT-SPECT and/or accelerometry/electromyography (EMG) recording were performed in a subgroup of patients. We analyzed the causes of erroneous PD diagnosis as well as the final diagnoses.Results : Mean age at PD diagnosis was 60.4 ± 14.8 years. Symptoms at onset were rest tremor (n = 19), gait instability (n = 7) and micrographia (n = 4). Mean duration before diagnosis correction was 8.4 ± 5.3 years. All patients were treated by antiparkinsonian drugs with a mean daily levodopa equivalent dose (LED) of 508.1 ± 528.4 mg. All 18 patients who underwent DaT-SPECT had a normal result. The most frequent final diagnoses were essential tremor (n = 11) and functional movement disorders (n = 9).Conclusion : Cases that have been initially diagnosed as PD and then progress in an atypical long-duration fashion may have been misdiagnosed. Absence of genuine bradykinesia, non-sustained response to antiparkinsonian drugs, or absence of levodopa-related side effects should prompt the clinician to reappraise the diagnosis and to consider performing a DaT-SPECT

Médias et journalisme

3e édition revue et complétée - Conférence permanente des directeurs·trices des unités de recherche en sciences de l’information et de la communication (CPDirSIC)International audienceLes recherches sur les médias et le journalisme abordent des questions à fort enjeu social et politique. Elles visent à rendre intelligible la fabrique desdiscours publics, médiatiques et politiques, dont ceux touchant, par exemple, à l’environnement, à la santé, à l’égalité et aux inégalités, aux usages desdata, aux violences, aux migrations. Qu’il soit question de la médiatisation du terrorisme ou du rôle des journalistes face à la terreur, des risques industriels, climatiques, sanitaires, de l’influence des discours sur les réseaux sociaux et, plus largement, de l’internet dans la construction des débats publics, sociaux et politiques, les recherches sur le journalisme et les médias permettent de comprendre les processus professionnels et communicationnels qui forgent les représentations communes, les repères sociaux et politiques qui configurent les événements, contribuent à la formation d’espaces publics pluriels et définissent des arènes dans lesquelles les acteurs de la démocratie ont à prendre position

A single-center series of 482 patients with functional motor disorders

International audienceFunctional motor disorders (FMD) are common and disabling. They are known to predominantly affect women and young to middle-aged patients, although they also occur during childhood or in the elderly. Demographic and clinical characteristics of patients with FMD are poorly known, since large series of consecutive patients are scarce.MethodsIn a chart review study, we retrospectively abstracted data from consecutive FMD patients who were referred to the Neurophysiology Department of the Salpêtrière University Hospital between 2008 and 2016 for treatment with repeated transcranial magnetic stimulation.Results482 patients were included. Most patients were women (73.7%). Median age at symptoms onset was 35.5 years and symptoms were mostly characterized by acute (47.3%) or subacute (46%) onset. Only 23% of patients were active workers, while 58.3% were unemployed because of FMD. Half of the patients had functional motor weakness (n = 241) whereas the other half had movement disorders (n = 241), mainly with tremor (21.1%) or dystonia (20.5%). Among all patients, 66.4% had psychiatric comorbidity and 82.6% reported a history of trauma in the 6 months before symptoms onset. No difference was found in age or gender according to clinical phenotypes.ConclusionThis large series will contribute to better characterize FMDs

Anterior Temporal Lobe Morphometry Predicts Categorization Ability

International audienceCategorization is the mental operation by which the brain classifies objects and events. It is classically assessed using semantic and non-semantic matching or sorting tasks. These tasks show a high variability in performance across healthy controls and the cerebral bases supporting this variability remain unknown. In this study we performed a voxel-based morphometry study to explore the relationships between semantic and shape categorization tasks and brain morphometric differences in 50 controls. We found significant correlation between categorization performance and the volume of the gray matter in the right anterior middle and inferior temporal gyri. Semantic categorization tasks were associated with more rostral temporal regions than shape categorization tasks. A significant relationship was also shown between white matter volume in the right temporal lobe and performance in the semantic tasks. Tractography revealed that this white matter region involved several projection and association fibers, including the arcuate fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, and inferior longitudinal fasciculus. These results suggest that categorization abilities are supported by the anterior portion of the right temporal lobe and its interaction with other areas

Impact of Transcranial Magnetic Stimulation on Functional Movement Disorders: Cortical Modulation or a Behavioral Effect?

IntroductionRecent studies suggest that repeated transcranial magnetic stimulation (TMS) improves functional movement disorders (FMDs), but the underlying mechanisms are unclear. The objective was to determine whether the beneficial action of TMS in patients with FMDs is due to cortical neuromodulation or rather to a cognitive-behavioral effect.MethodConsecutive patients with FMDs underwent repeated low-frequency (0.25 Hz) magnetic stimulation over the cortex contralateral to the symptoms or over the spinal roots [root magnetic stimulation (RMS)] homolateral to the symptoms. The patients were randomized into two groups: group 1 received RMS on day 1 and TMS on day 2, while group 2 received the same treatments in reverse order. We blindly assessed the severity of movement disorders before and after each stimulation session.ResultsWe studied 33 patients with FMDs (dystonia, tremor, myoclonus, Parkinsonism, or stereotypies). The median symptom duration was 2.9 years. The magnetic stimulation sessions led to a significant improvement (>50%) in 22 patients (66%). We found no difference between TMS and RMS.ConclusionWe suggest that the therapeutic benefit of TMS in patients with FMDs is due more to a cognitive-behavioral effect than to cortical neuromodulation

Activation during <i>abstraction</i> and <i>similarity detection</i>.

<p>Activation is displayed on a rendered brain. Only clusters surviving a family-wise error (FWE) correction (p<.05) are reported (cluster extent: 150 voxels). Details regarding activated foci are displayed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034164#pone-0034164-t001" target="_blank">table 1</a>.</p