RT Journal Article
SR Electronic
T1 Synaptic Action of the Olivocerebellar System on Cerebellar Nuclear Spike Activity
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 14708
OP 14720
DO 10.1523/JNEUROSCI.3323-11.2011
VO 31
IS 41
A1 Timothy A. Blenkinsop
A1 Eric J. Lang
YR 2011
UL http://www.jneurosci.org/content/31/41/14708.abstract
AB Cerebellar output is necessary for the ideal implementation of many nervous system functions, particularly motor coordination. A key step toward understanding the generation of this output is characterizing the factors that shape the activity of the cerebellar nuclei (CN). There are four major sources of synaptic input that modulate CN activity; collaterals of climbing and mossy fibers are two, and the remaining two are provided by Purkinje cell (PC) axons in the form of simple spikes (SSs) and complex spikes (CSs). Most hypotheses of cerebellar function focus on SSs as the primary determinant of CN activity. However, it is likely that CSs also cause significant direct effects on CN activity, something that is rarely considered. To explore this possibility, we recorded from synaptically connected PC–CN neuron cell pairs in rats. Cross-correlograms of CS and CN activity from such recordings demonstrate that spontaneous CSs have a strong inhibitory effect on CN activity, apparently sufficient, in some cases, to trigger changes in the intrinsic excitability of the CN neuron that long outlast the underlying CS-mediated GABAergic IPSP. Furthermore, many CS–CN correlograms show an initial excitatory response, demonstrating the ability of climbing fiber collaterals to significantly excite CN neurons. A substantial fraction (24%) of correlograms displayed an excitation–inhibition sequence, providing evidence that a CN neuron often receives collaterals from the same olivocerebellar axons as innervate the PCs projecting to it. Thus, excitation followed by inhibition appears to be a hard-wired response pattern of many CN neurons to olivocerebellar activity.