The dynamic relationship between cerebellar Purkinje cell simple spikes and complex spike spikelet number

Purkinje cells are central to cerebellar function as they form the sole output of the cerebellar cortex. They exhibit two distinct types of action potential: simple spikes and complex spikes, and it is widely accepted that interaction between these two types of impulse is central to cerebellar cortical information processing. Previous investigations of the interactions between simple spikes and complex spikes have mainly considered complex spikes as unitary events. However, complex spikes are composed of an initial large spike followed by a number of secondary components, termed spikelets. The number of spikelets within individual complex spikes is highly variable and the extent to which differences in complex spike spikelet number affects simple spike activity (and vice versa) remains poorly understood. In anaesthetized adult rats we have found that Purkinje cells recorded from the posterior lobe vermis and hemisphere that have high simple spike firing frequencies precede complex spikes with greater numbers of spikelets. This finding was also evident in a small sample of Purkinje cells recorded from the posterior lobe hemisphere in awake cats. In addition, complex spikes with a greater number of spikelets were associated with a subsequent reduction in simple spike firing rate. We therefore suggest that one important function of spikelets is the modulation of Purkinje cell simple spike firing frequency, which has implications for controlling cerebellar cortical output and motor learning.

This article is protected by copyright. All rights reserved

from Physiology via xlomafota13 on Inoreader http://ift.tt/1X6ANTE
via IFTTT