Neuromagnetic brain responses to words from semantic sub- and supercategories

Ramin Assadollahi,Brigitte Rockstroh

doi:10.1186/1471-2202-6-57

Ramin Assadollahi, Brigitte Rockstroh

Open Access

https://doi.org/10.1186/1471-2202-6-57

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Journal: BMC Neuroscience	Publication Date: Jan 1, 2005
Citations: 36	License type: cc-by

Affiliation: University of Konstanz

Abstract

BackgroundWe explored spatio-temporal patterns of cortical activity evoked by written words from super-ordinate and sub-ordinate semantic categories and hoped to find a differential cortical and/or temporal distribution of the brain response depending on the level of the categories. Twenty-three subjects saw 360 words belonging to six sub-ordinate categories (mammals, birds, fish, fruit, flowers, trees) within two super-ordinate categories (fauna, flora). Visually evoked magnetic fields were determined from whole-head (148-sensor) magnetoencephalography and analyzed in the source space (Minimum Norm Estimate).ResultsActivity (MNE amplitudes) 100–150 ms after stimulus onset in the left occipito-temporal area distinguished super-ordinate categories, while later activity (300–550 ms) in the left temporal area distinguished the six sub-ordinate categories.ConclusionOur results document temporally and spatially distinct processing and representation of words according to their categorical information. If further studies can rule out possible confounds then our results may help constructing a theory about the internal structure of entries in the mental lexicon and its access.

Highlights

We explored spatio-temporal patterns of cortical activity evoked by written words from super-ordinate and sub-ordinate semantic categories and hoped to find a differential cortical and/or temporal distribution of the brain response depending on the level of the categories
The mental lexicon is usually considered to be a compilation of linguistic information, with each word having an entry
The precise structure of a lexical entry continues to be a topic of investigation and discussion

Summary

Introduction

We explored spatio-temporal patterns of cortical activity evoked by written words from super-ordinate and sub-ordinate semantic categories and hoped to find a differential cortical and/or temporal distribution of the brain response depending on the level of the categories. Twenty-three subjects saw 360 words belonging to six sub-ordinate categories (mammals, birds, fish, fruit, flowers, trees) within two super-ordinate categories (fauna, flora). The mental lexicon is usually considered to be a compilation of linguistic information, with each word having an entry. A lexical entry for a word should contain information about its pronunciation, its orthography, its syntactic properties, and its semantic information. We explored the aspect of categories within semantic information. Is the category information represented within one brain compartment or in a distributed fashion? How and where is such information encoded in the brain? Is the category information represented within one brain compartment or in a distributed fashion?

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Conclusion