Neural evidence for impaired action selection in right hemiparetic cerebral palsy.

Recent studies suggest that in addition to low-level motor impairments, individuals with hemiparetic cerebral palsy (HCP) are characterized by anticipatory action planning deficits as well. In the present EEG study we investigated the neural and temporal dynamics of action planning in participants with right-sided HCP (n=10) and in left-handed control subjects (n=10). An anticipatory planning task was used in which participants were required to grasp and rotate a hexagonal knob over different angles (60 degrees, 120 degrees or 180 degrees). At a behavioral level, participants with HCP were slower in their movements and often selected an inappropriate grip when grasping the object. At a neural level, individuals with HCP showed a strong reduction in the amplitude of the P2 component, likely reflecting an impaired process of action selection. In addition, a strong correlation was observed between the P2 amplitude and grasping and rotation times. The P2 component was localized to sources in the dorsal posterior cingulate cortex (dPCC), an area that is known to be involved in orienting visual body parts in space. Together these findings suggest that anticipatory planning deficits in cerebral palsy arise mainly due to an impaired process of action selection.