Biology subjects

Volle, E.

Publications and source records attributed to Volle, E..

3 recordsLinked to original sources

bioRxiv2017

Anterior temporal lobe morphometry predicts categorization ability

Categorization 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 grey 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.\n\nHighlightsO_LIAnterior temporal lobe morphometry correlates with categorization performances\nC_LIO_LISemantic is associated with a more rostral temporal region than shape categorization\nC_LIO_LISemantic categorization performances are associated with right temporal connections\nC_LI

neuroscience↗

bioRxiv2017

"A mosquito bites and a butterfly flies": a specific response type of frontal patients in a similarity task

BackgroundPatients with neurodegenerative diseases affecting the frontal lobes have difficulties in categorization tasks, such as the similarity tasks. They give two types of unusual response to the question: \"In what way are an orange and a banana alike?\", either a differentiation (\"one is yellow, the other is orange\") or a concrete similarity (\"they are sweet\").\n\nObjectiveTo characterize the categorization deficit of frontal patients and develop a short diagnostic tool to assess the nature of these difficulties.\n\nMethodWe analyzed the responses provided by frontal and non-frontal neurodegenerative patients in a novel verbal similarity task (SimiCat). We included 40 frontal patients with behavioral variant fronto-temporal dementia (bvFTD) and progressive supranuclear palsy (PSP), 23 patients with Alzheimers disease (AD) and 41 healthy matched controls. Responses that did not correspond to the expected taxonomic category (e.g.: fruits) were considered as errors.\n\nResultsAll patients groups were impaired at the SimiCat test compared to controls. Differentiation errors were specific of frontal patients. Receiver operating characteristic analyses showed that a cut-off of two differentiation errors or more achieved 85% sensitivity of 100% specificity to discriminate bvFTD from AD. A short version of the test (<5 min) showed similar discriminative validity as the full version.\n\nConclusionDifferentiation responses were specific of frontal patients. The SimiCat demonstrates good discriminative validity to differentiate bvFTD and AD. The short version of the test is a promising diagnostic tool that will need validation in future studies.

neuroscience↗

bioRxiv2017

Advanced Lesion Symptom Mapping Analyses And Implementation As BCBtoolkit

BackgroundPatients with brain lesions provide a unique opportunity to understand the functioning of the human mind. However, even when focal, brain lesions have local and remote effects that impact functionally and structurally connected circuits. Similarly, function emerges from the interaction between brain areas rather than their sole activity. For instance, category fluency requires the association between executive, semantic and language production functions.\n\nFindingsHere we provide, for the first time, a set of complementary solutions to measure the impact of a given lesion upon the neuronal circuits. Our methods, which were applied to 37 patients with a focal frontal brain lesion, revealed a large set of directly and indirectly disconnected brain regions that had significantly impacted category fluency performance. The directly disconnected regions corresponded to areas that are classically considered as functionally engaged in verbal fluency and categorization tasks. These regions were also organized into larger directly and indirectly disconnected functional networks, including the left ventral fronto-parietal network, whose cortical thickness correlated with performance on category fluency.\n\nConclusionsThe combination of structural and functional connectivity together with cortical thickness estimates reveals the remote effects of brain lesions, provide for the identification of the affected networks and strengthen our understanding of their relationship with cognitive and behavioural measures. The methods presented are available and freely accessible in the BCBtoolkit as supplementary software (http://toolkit.bcblab.com).

neuroscience↗