Subthalamic nucleus activity in the processing of body and mental action verbs in people with Parkinson's disease

Local field potentials evoked by body action and mental action verbs were recorded in the subthalamic nucleus (STN) of 18 patients with Parkinson's disease through the electrodes implanted for deep brain stimulation. Compared with the medication on-condition, the medication off-condition showed a difference in activity in the early time segments, mainly in the right STN, with larger amplitudes for body action verbs. In the on-condition a similar pattern was detected in the left STN. These patterns of early differences in activity evoked by different types of verbs might indicate the potential of the STN to rapidly detect relevant behavioural clues in verbal content and to integrate these in subsequent cortico-subcortical interactions. In addition, these lateralizations allow speculations about shifts in processing activity correlating with dopaminergic denervation. Whether this detection relies on phonological, semantic or grammatical clues remains an open question.