Functional organization of the circuits connecting the cerebral cortex and the basal ganglia: implications for the role of the basal ganglia in epilepsy.

The basal ganglia are composed of a set of forebrain structures implicated in the adaptive control of behaviour. These structures process information originating from the entire cerebral cortex, as well as from nonspecific thalamic nuclei and the amygdala. In turn, they redistribute the integrated signals toward thalamic and brainstem nuclei related to motor, premotor, prefrontal and limbic cortical areas. During the two last decades, there has been increasing experimental evidence that the basal ganglia circuitry may be part of a remote control system influencing the spread of epileptic seizures. In the present article, we review the basic principles of the functional organization of the basal ganglia and provide experimental data on the activity that is transmitted by the cerebral cortex to the input stage of the basal ganglia during absence seizures. The functional organization of the basal ganglia supports the current hypothesis that these structures can dynamically control generalized seizures through their input-output relationships.