The effect of stimulus-response compatibility on cortical motor activation

Stimulus-response compatibility (SRC) is a general term describing the rela tionship between a triggering stimulus and its associated motor response. T he relationship between stimulus and response can be manipulated at the lev el of the set of stimulus and response characteristics (set-level) or at th e level of the mapping between the individual elements of the stimulus and response sets (element-level). We used functional magnetic resonance imagin g (fMRI) to investigate the effects of SRC on functional activation in cort ical motor areas. Using behavioral tasks to separately evaluate set- and el ement-level compatibility, and their interaction, we measured the volume of functional activation in 11 cortical motor areas, in the anterior frontal cortex, and in the superior temporal lobe. Element-level compatibility effe cts were associated with significant activation in the pre-supplementary mo tor area (preSMA), the dorsal (PMd) and ventral (PMv) premotor areas, and t he parietal areas (inferior, superior, intraparietal sulcus, precuneus). Th e activation was lateralized to the right hemisphere for most of the areas. Set-level compatibility effects resulted in significant activation in the inferior frontal gyri, anterior cingulate and cingulate motor areas, the PM d, PMv, preSMA, the parietal areas (inferior, superior, intraparietal sulcu s, precuneus), and in the superior temporal lobe. Activation in the majorit y of these areas was lateralized to the left hemisphere. Finally, there was an interaction between set and element-level compatibility in the middle a nd superior frontal gyri, in an area co-extensive with the dorsolateral pre frontal cortex, suggesting that this area provided the neural substrate for common processing stages, such as corking memory and attention, which are engaged when both levels of SRC are manipulated at once. (C) 2001 Academic Press.