Distributed cell assemblies for general lexical and category-specific semantic processing as revealed by fMRI cluster analysis.

Details

Serval ID
serval:BIB_6D296B6B5028
Type
Article: article from journal or magazin.
Collection
Publications
Title
Distributed cell assemblies for general lexical and category-specific semantic processing as revealed by fMRI cluster analysis.
Journal
Human Brain Mapping
Author(s)
Pulvermüller F., Kherif F., Hauk O., Mohr B., Nimmo-Smith I.
ISSN
1097-0193 (Electronic)
ISSN-L
1065-9471
Publication state
Published
Issued date
2009
Volume
30
Number
12
Pages
3837-3850
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Abstract
Here, we ask whether frontotemporal cortex is functionally dissociated into distributed lexical and category-specific semantic networks. To this end, fMRI activation patterns elicited during the processing of words from different semantic categories were categorized using k-means cluster algorithms. Results showed a distributed pattern of inferiorfrontal, superiortemporal, and fusiform activation shared by different word categories. This shared activation contrasted with patterns of category-specific semantic activation in widely distributed neural systems. Clustering revealed congruent functional specificity of focal area activations in frontal and temporal cortex; thus suggesting a correspondence between functional partitionings of frontocentral mirror neuron systems and those of inferiortemporal lexical and semantic circuits. Action words related to the face, arms, and legs specifically activated the motor system in a somatotopic manner, whereas form-related words activated prefrontal areas. Similar functional specificity was evident in temporal cortex, where a different semantic topography emerged for form- and action-related words. Results were replicated in a separate data set, therefore recommending fMRI cluster analysis as a reliable method for scrutinizing the brain basis of lexical, semantic, and conceptual systems in humans. As focal modules do not explain the distributed character of functionally specific clusters and their distinct topographies are at variance with general distributed processing accounts, the functionally-homogenous distributed clusters specific to semantic types are best explained by specifically-distributed cortical circuits which, similar to Hebbian cell assemblies, represent functional units with specific roles in cognitive processing, especially in lexical and semantic access and memory.
Keywords
Adult, Brain Mapping, Cerebral Cortex/physiology, Cluster Analysis, Female, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Photic Stimulation, Semantics, Visual Perception/physiology
Pubmed
Web of science
Create date
22/01/2013 15:38
Last modification date
20/08/2019 15:26
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