Functional Connectivity and Information Processing in the Basal Ganglia of Normal and Parkinsonian Monkeys
The mode of information processing (e. g., parallel or integrative processing) in the basal ganglia circuitry is determined by the level of system coupling, namely by the functional connections (fully segregated or fully overlapping) between the input and output structures of the circuit. To test the degree of functional coupling and possible models of information processing in the basal ganglia, we studied the cross-correlation histograms of simultaneously recorded neurons in the globus pallidus of rhesus and vervet (African green) monkeys before and after MPTP treatment.
In dramatic contrast to similar studies of other neuronal systems, almost all pairs of pallidal neurons fired independently in the normal monkey. Following MPTP treatment and the development of tremor and other parkinsonian symptoms, significant oscillations (around 5–7 and 10–14 Hz) were found in the auto- and cross-correlation histograms of many pallidal neurons.
The results support the view that the basal ganglia circuits are built as a mixed coupled system that is un- or weakly-coupled in the normal state and strongly coupled in the Parkinsonian state. Synchronized oscillatory neural activity in the basal ganglia probably plays a major role in the tremor phenomena of Parkinson’s disease.
KeywordsBasal Ganglion Functional Connectivity Globus Pallidus Subthalamic Nucleus Vervet Monkey
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