The Role of Frontal Cortex in Object and Action Naming: A TMS Study

Functional and neuroanatomical differences between noun and verb processing is a well-established phenomenon. Thus, empirical data show that left dorsolateral cortex is specifically involved in verb processing. The research question of this study was whether the difference between verbs and nouns is conceptual or grammatical in nature.

An experiment with 30 neurologically healthy participants was conducted using the Transcranial Magnetic Stimulation method (TMS). TMS non-invasively affects restricted cortical areas with magnetic field, temporarily modulating their function. The participants named actions and action-related objects in four conditions: left and right inferior frontal gyrus stimulation, vertex stimulation, and sham vertex stimulation (control condition).

As a result, facilitation effect for action naming (measured as increase in accuracy) was found in the left inferior frontal cortex stimulation condition, as compared to the sham condition. This result confirmed once again left prefrontal specificity for verb processing. The hypothesis about involvement of these regions in processing of action-related words irrespective of their grammatical class wasn’t confirmed.

The project was carried out in collaboration with members of Center for Cognition & Decision Making Yury Shtyrov and Matteo Feurra.

A master’s thesis was successfully defended by Vidya Thimmanahalli Somashekarappa based on the results of the project.