Coinciding Decreases in Discharge Rate Suggest That Spontaneous Pauses in Firing of External Pallidum Neurons Are Network Driven
Journal of Neuroscience. 2015-04-29; 35(17): 6744-6751
DOI: 10.1523/jneurosci.5232-14.2015
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Schechtman E(1), Adler A(2), Deffains M(3), Gabbay H(4), Katabi S(4), Mizrahi A(4), Bergman H(3).
Author information:
(1)Edmond and Lily Safra Center for Brain Sciences, The Hebrew University,
Jerusalem 91904, Israel, and .
(2)Edmond and Lily Safra Center for Brain Sciences, The Hebrew University,
Jerusalem 91904, Israel, and.
(3)Edmond and Lily Safra Center for Brain Sciences, The Hebrew University,
Jerusalem 91904, Israel, and Department of Medical Neurobiology, Institute for
Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine,
Jerusalem 91120, Israel.
(4)Department of Medical Neurobiology, Institute for Medical Research
Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem 91120,
Israel.
The external segment of the globus pallidus (GPe) is one of the core nuclei of
the basal ganglia, playing a major role in normal control of behavior and in the
pathophysiology of basal ganglia-related disorders such as Parkinson’s disease.
In vivo, most neurons in the GPe are characterized by high firing rates (50-100
spikes/s), interspersed with long periods (∼0.6 s) of complete silence, which
are termed GPe pauses. Previous physiological studies of single and pairs of GPe
neurons have failed to fully disclose the physiological process by which these
pauses originate. We examined 1001 simultaneously recorded pairs of
high-frequency discharge GPe cells recorded from four monkeys during
task-irrelevant periods, considering the activity in one cell while the other is
pausing. We found that pauses (n = 137,278 pauses) coincide with a small yet
significant reduction in firing rate (0.78 ± 0.136 spikes/s) in other GPe cells.
Additionally, we found an increase in the probability of the simultaneously
recorded cell to pause during the pause period of the « trigger » cell.
Importantly, this increase in the probability to pause at the same time does not
account for the reduction in firing rate by itself. Modeling of GPe cells as
class 2 excitability neurons (Hodgkin, 1948) with common external inputs can
explain our results. We suggest that common inputs decrease the GPe discharge
rate and lead to a bifurcation phenomenon (pause) in some of the GPe neurons.
Copyright © 2015 Schechtman et al.