Cognitive- and movement-related potentials recorded in the human basal ganglia

Sources of potentials evoked by cognitive processing of sensory and motor activities were studied in 9 epilepsy surgery candidates with electrodes implanted in the basal ganglia (BG), mostly in the putamen. Several contacts were also located in the pallidum and the caudate. The recorded potentials were related to a variety of cognitive and motor activities (attentional, decisional, time estimation, sensory processing, motor preparation, and so on). In five different tests, we recorded P3-like potentials evoked by auditory and visual stimuli and sustained potential shifts in the Bereitschaftspotential and Contingent Negative Variation protocols. All of the studied potentials were generated in the BG. They were recorded from all over the putamen. Various potentials on the same lead or nearby contacts were recorded. A functional topography in the BG was not displayed. We presume that the cognitive processes we studied were produced in clusters of neurons that are organized in the basal ganglia differently than the known functional organization, e.g., of motor functions. The basal ganglia, specifically the striatum, may play an integrative role in cognitive information processing, in motor as well as in nonmotor tasks. This role seems to be nonspecific in terms of stimulus modality and in terms of the cognitive context of the task.