Evidence for premotor cortex activity during dynamic visuospatial imagery from single-trial functional magnetic resonance imaging and event-related slow cortical potentials

A strong correspondence has been repeatedly observed between actually perfo rm and mentally imagined object rotation. This suggests an overlap in the b rain regions involved in these processes. Functional neuroimaging studies h ave consistently revealed parietal and occipital cortex activity during dyn amic visuospatial imagery. However, results concerning the involvement of h igher-order cortical motor areas have been less consistent. We investigated if and when premotor structures are active during processing of a three-di mensional cube comparison task that requires dynamic visuospatial imagery. In order to achieve a good temporal and spatial resolution, single-trial fu nctional magnetic resonance imaging (fMRI) and scalp-recorded event-related slow cortical potentials (SCPs) were recorded from the same subjects in tw o separate measurement sessions. In order to reduce inter-subject variabili ty in brain activity due to individual differences, only male subjects (n = 13) with high task-specific ability were investigated. Functional MRI reve aled consistent bilateral activity in the occipital (Brodmann area BA18/19) and parietal cortex (BA7), in lateral and medial premotor areas (BA6), the dorsolateral prefrontal cortex MAW, and the anterior insular cortex. The t ime-course of SCPs indicated that task-related activity in these areas comm enced approximately 550-650 ms after stimulus presentation and persisted un til task completion. These results provide strong and consistent evidence t hat the human premotor cortex is involved in dynamic visuospatial imagery. (C) 2001 Academic Press.