Neuronal Synchronization of Tonically Active Neurons in the Striatum of Normal and Parkinsonian Primates. Raz, Aeyal, Ariela Feingold, Valentina Zelanskaya, Eilon Vaadia and Hagai Bergman. Department of Physiology and the Center for Neural Computation, The Hebrew University - Hadassah Medical School, P.O.Box 12272, Jerusalem 91120, Israel, E-mail: hagaib@md2.huji.ac.il.
APStracts 3:0118N, 1996.
SUMMARY AND CONCLUSIONS
1. Previous studies indicate that tonically active neurons (TANs) are the cholinergic interneurons of the striatum and predict that their activity is synchronized. To test if TANs do fire synchronously, and whether dopamine depletion affects their synchronization, we recorded the simultaneous activity of several TANs in the putamen of two vervet monkeys before and after 1- methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment. 2. Crosscorrelation analysis revealed that most pairs of TANs (33/54; 61.1%) fire synchronously at +/- 60 ms delay. Correlated activity was more common between neurons with characteristic response to reward (17/19 pairs; 89.5%). 3. Crosscorrelation study of twenty-four triplets of TANs showed synchronization of spiking activity of all three TANs in only 29.2% of cases (7/24 triplets). Correlated activity of two out of three possible pairs was found in 25% of the cases. 4. Following MPTP treatment and the development of parkinsonian symptoms, most TANs auto and cross-correlograms (22/28 units; 78.6% and 23/28 pairs; 82.1%) became oscillatory. The number of correlated pairs was slightly increased (24/28; 85.7%). The strength of the synchronization was not significantly different from the normal values. 5. These findings support the notion that TANs function as distributed, partially overlapping synchronized networks. However, a normal dopaminergic system is not essential for synchronization of TANs; on the contrary, dopaminergic activity may even have a desynchronizing effect on the basal ganglia's system.

Received 3 April 1996; accepted in final form 4 June 1996.
APS Manuscript Number J275-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 17 June 96