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Imagery or meaning? Evidence for a semantic origin of category-specific brain activity in metabolic imaging
Article first published online: 31 MAR 2008
© The Authors (2008)
European Journal of Neuroscience
Volume 27, Issue 7, pages 1856–1866, April 2008
How to Cite
Hauk, O., Davis, M. H., Kherif, F. and Pulvermüller, F. (2008), Imagery or meaning? Evidence for a semantic origin of category-specific brain activity in metabolic imaging. European Journal of Neuroscience, 27: 1856–1866. doi: 10.1111/j.1460-9568.2008.06143.x
- Issue published online: 31 MAR 2008
- Article first published online: 31 MAR 2008
- Received 30 July 2007, revised 10 January 2008, accepted 11 February 2008
- cell assemblies;
- multiple regression;
- visual word recognition;
- word frequency
Category-specific brain activation distinguishing between semantic word types has imposed challenges on theories of semantic representations and processes. However, existing metabolic imaging data are still ambiguous about whether these category-specific activations reflect processes involved in accessing the semantic representation of the stimuli, or secondary processes such as deliberate mental imagery. Further information about the response characteristics of category-specific activation is still required. Our study for the first time investigated the differential impact of word frequency on functional magnetic resonance imaging (fMRI) responses to action-related words and visually related words, respectively. First, we corroborated previous results showing that action-relatedness modulates neural responses in action-related areas, while word imageability modulates activation in object processing areas. Second, we provide novel results showing that activation negatively correlated with word frequency in the left fusiform gyrus was specific for visually related words, while in the left middle temporal gyrus word frequency effects emerged only for action-related words. Following the dominant view in the literature that effects of word frequency mainly reflect access to lexico-semantic information, we suggest that category-specific brain activation reflects distributed neuronal ensembles, which ground language and concepts in perception-action systems of the human brain. Our approach can be applied to any event-related data using single-stimulus presentation, and allows a detailed characterization of the functional role of category-specific activation patterns.