There are two views as to the character of basal-ganglia processing - processing by segregated parallel circuits or by information sharing. To distinguish between these views, we studied the simultaneous activity of neurons in the output stage of the basal ganglia with cross-correlation techniques. The firing of neurons in the globus pallidus of normal monkeys is almost always uncorrelated. However, after dopamine depletion and induction of parkinsonism by treatment with 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP), oscillatory activity appeared and the firing of many neurons became correlated. We conclude that the normal dopaminergic system supports segregation of the functional subcircuits of the basal ganglia, and that a breakdown of this independent processing is a hallmark of Parkinson's disease.
Bibliographical noteFunding Information:
This study was supported by grants from the Israel Academy of Science and the US–Israel Binational Scientific Foundation. We thank V. Zelanskaya for assistance with the histology, V. Sherkanski and M. Nakar for their continuous technical support, and T. Wichmann, E. Simon and O. Donchin for critical reading of this manuscript.