Anatomical and functional parcellation of the human lateral premotor cortex.

The lateral premotor cortex (PM) of the macaque monkey is an anatomically multifaceted area, which serves multiple sensorimotor and cognitive functions. While evidence for the functional organization of human premotor cortex accumulates, much less is known about the underlying anatomical properties of this brain region. We used diffusion tractography and functional magnetic resonance imaging (fMRI) to investigate whether the precentral gyrus in humans can be segregated on the basis of anatomical connectivity and of functional activation in a set of cognitive and motor tasks. Tractographic data suggested a distinction between ventral and dorsal premotor cortex, and furthermore inferior and superior subparcellation of both. Functional MRI data corroborated these four areas, showing that anatomical parcellation predicts the distribution of functional activation and vice versa (preliminary evidence). These results may encourage the application of combining diffusion tractography and fMRI in vivo in order to shed light on the correspondence of brain function and anatomy.