The causal role of category-specific neuronal representations in the left ventral premotor cortex (PMv) in semantic processing

The left ventral premotor cortex (PMv) is preferentially activated by exemplats of tools, suggestive of category specificity in this region Here we used state-dependent transcranial magnetic stimulation (TMS) to investigate the causal role Of such category-specific neuronal representations in the encoding of tool words Priming to a category name (either Tool or Animal) Was used with the objective of modulating the initial activation state of this region prior to application of TMS and the presentation of the target stimulus When the target word was all exemplar of the Tool category, the effects of TMS applied civet PMv (but not PMd) interacted with priming history by facilitating reaction times on incongruent trials while not affecting congruent trials This congruency/TMS interaction implies that the Tool and Animal primes had a differential effect oil the initial activation state of the left PMv and implies that this region is one neural locus of category-specific behavioral priming for the Tool category TMS applied over PMv had no behavioral effect when the target stimulus was an exemplar of the Animal category, regardless of whether the target word was congruent or incongruent with the prime That TMS applied over the left PMv interacted with a priming effect that extended from the category name (Tool) to exemplars of that category suggests that this region contains neuronal representation associated with a specific semantic category Our results also demonstrate that the state-dependent effects obtained in the combination of visual priming and TMS are useful in the Study of higher-level cognitive functions (C) 2009 Elsevier Inc All rights reserved