Functional differentiation of the premotor cortex:Behavioural and brain imaging studies in humans

The premotor cortex is a brain structure that is involved in the preparation of movements. It has an important role in the final integration of task-related information and to funnel this to the primary motor cortex, which subsequently causes the execution of a movement. Premotor areas can also influence motor output through their direct interactions with both the spinal cord. Within the premotor cortex, the ventral premotor cortex (PMv), dorsal premotor cortex (PMd) and supplementary motor area (SMA) can be identified. These premotor areas differ in both functional specialization and connectivity with other areas. Behavioural studies and functional and anatomical MRI studies were used to study this functional and anatomical specialization. Impairment of premotor cortex function may arise from a local lesion in the premotor cortex itself or in areas inflicting disconnection with the premotor areas. Another cause of impaired premotor cortex function is a reduced input from deeper brain structures, which occurs in Parkinson’s disease (PD). This thesis aims to focus on various aspects of premotor cortex function, particularly during writing and scaling of size. Therefore, we did behavioural and functional MRI studies in healthy individuals. We showed that there is functional specialization of premotor cortex areas during different aspects of writing. Subsequently, we investigated patients with PD and patients with a tumor, in which conditions of compromised premotor cortex function are studied. Based on these studies we could make specific assumptions about premotor cortex areas