Functional coupling underlying motor and cognitive functions of the dorsal premotor cortex.

This review article discusses mechanisms of how distinct behavioral operations are organized by different modules distributed in the frontal cortex. Cognitive manipulation often requires a flow of multiple elementary sub-operations processed in specialized brain regions. The dorsolateral prefrontal cortex (dlPFC) is likely responsible for attentional selection, which orients organisms' mental resources to behaviorally relevant information. The dorsal premotor cortex (PMd) is implicated to possess a functional gradient along the rostral-caudal axis. The rostral sector of the PMd (pre-PMd) is involved in various cognitive/premovement processes while its caudal sector (PMd proper) primarily controls actual movement. Neurophysiology studies in monkeys have shown that the pre-PMd, when functionally coupled with the dlPFC, may transform independent working memory items into a single sequence (sequence generation). A neuroimaging study has shown that the pre-PMd is indeed involved in sequence generation under the influence of the dlPFC in humans. It has been also indicated that the dlPFC and the pre-PMd are functionally coupled when attentional selection and sequence generation are to be unified for serial information processing. Functional interplay through the prefrontal-premotor connections may mediate the integration of specific sub-operations for multi-step cognitive manipulation. Furthermore, evidence from a meta-analysis of the imaging literature is argued for an idea that the coupling pattern with other frontal cortical areas may characterize of the function of the pre-PMd and PMd proper in various motor and cognitive tasks.