Neural correlates of overcoming interference from instructed and implemented stimulus-response associations.

One of the major evolutionary advances of human primates in the motor domain is their ability to use verbal instructions to guide their behavior. Despite this fundamental role of verbal information for our behavioral regulation, the functional and neural mechanisms underlying the transformation of verbal instructions into efficient behavior are still poorly understood. To gain deeper insights into the motor representation of verbal instructions, we investigated the neural circuits involved in overcoming interference from stimulus- response (S-R) mappings that are merely instructed and S-R mappings that are implemented. Implemented and instructed S-R mappings revealed a partly overlapping pattern of fronto-parietal brain activity when compared with a neutral condition. However, the direct contrast revealed a clear difference with stronger activation for the implemented condition in the ACC, bilateral inferior parietal cortex, the cerebellum and the precentral sulcus. This indicates that instructed S-R mappings share some properties with implemented S-R mappings but that they are lacking the motor-related properties of implemented mappings.