The role of the left frontal lobe in action naming: rTMS evidence

BACKGROUND: Neuropsychological and neuroimaging studies suggest that whereas the left temporal neocortex plays a crucial role in all tasks involving lexical-semantic processing, some regions of the left prefrontal convexity are selectively recruited during verb processing. OBJECTIVE: To determine if there are different neural correlates for noun and verb processing in the human brain. METHODS: Repetitive transcranial magnetic stimulation (rTMS), 20 Hz at 90% of the motor threshold, was applied to left or right prefrontal brain during object- and action-naming tasks in nine healthy subjects. RESULTS: A shortening of naming latency for actions was observed only after stimulation of left prefrontal cortex. CONCLUSION: The involvement of the left dorsolateral frontal cortex in action naming was demonstrated using rTMS.