Semantic Category Interference in Overt Picture Naming: An Meg-study

Abstract:
The study investigated the neuronal basis of the retrieval of word forms from the mental lexicon. The semantic category interference effect reflects the finding that for overt naming volunteers are slower when naming pictures out of a sequence of items from the same semantic category than from different categories. Participants named pictures blockwise either in the context of same- or mixed-category items while the brain response was registered using magnetoencephalography (MEG). Fifteen out of twenty participants showed significantly longer response latencies during the same-category blocks. MEG data from those fifteen were submitted to a current source density (CSD) analysis. A principle component analysis was applied to decompose the grand average CSD distribution into spatial subcomponents (factors). The spatial factor indicating left temporal activity revealed significantly different activation for the same-category compared to the mixed-category condition in the time window between 150 and 225 ms post picture onset. These findings indicate a major involvement of the left temporal cortex in the semantic interference effect. As this effect has been shown to take place at the level of lexical selection, the data suggest that the left temporal cortex supports processes of lexical retrieval during production.