S85 The modulatory role of subcortical structures on cortical cognitive functions

Abstract

A direct way of studying the function of the subcortical nuclei is neurophysiological recording of event related electrical activities, i.e. the evoked potentials and oscillations, via the intracranial deep brain electrodes. Based on our own electrophysiological recordings and results of other groups we suggest that the subcortical nuclei are involved in the processing of higher cortical functions. We recorded cognitive tasks-related activities in putamen, pallidum, caudate, ncl. subthalamicus, anterior and posterolateral thalamus. Recordings were performed via intracerebral electrodes (SEEG) or deep brain stimulation (DBS) electrodes in patients with pharmacoresistant epilepsy from basal ganglia ( putamen, pallidum, caudate) and anterior nuclei of thalamus; in patients with Parkinson’s disease and dystonia from the subthalamic nucleus and internal pallidum; posterolateral thalamus was implanted for the treatment of pain. The cognitive role of the subcortical structures was tested in various protocols exploring the cognitive involvement in the motor control, executive functions, attention and orientation, complex visuo-motor tasks, memory encoding and retrieval. A general hypothesis explaining the role of the subcortical structures and the cortico-subcortical interactions in processing cognitive activities is still missing. We suggest that there is a plastic functional network of cortical and subcortical structures that are simultaneously active, with all the time changing mutual interconnections of active and inactive zones in a task related manner. 1. Basal ganglia – thalamocortical loop act as an modulator which may be involved in tuning the widespread cortical functions. An integrative role of the basal ganglia with subsequent modulation of cortical cognitive processing is suggested. 2. Thalamic specific nuclei may modulate specific cognitive functions probably via contextual modulation of certain cortical areas. Subcortical structures, in particular basal ganglia, should be seriously considered as a potential target for neuromodulatory treatment of diseases with cognitive disturbances.