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Firing Patterns of Cerebellar Purkinje Cells During Locomotion and Sleep

Citation

Sauerbrei, Britton Alan (2016) Firing Patterns of Cerebellar Purkinje Cells During Locomotion and Sleep. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9G15XS8. http://resolver.caltech.edu/CaltechTHESIS:12012015-143528464

Abstract

The cerebellum is a major supraspinal center involved in the coordination of movement. The principal neurons of the cerebellar cortex, Purkinje cells, receive excitatory synaptic input from two sources: the parallel and climbing fibers. These pathways have markedly different effects: the parallel fibers control the rate of simple sodium spikes, while the climbing fibers induce characteristic complex spike bursts, which are accompanied by dendritic calcium transients and play a key role in regulating synaptic plasticity. While many studies using a variety of species, behaviors, and cerebellar regions have documented modulation in Purkinje cell activity during movement, few have attempted to record from these neurons in unrestrained rodents. In this dissertation, we use chronic, multi-tetrode recording in freely-behaving rats to study simple and complex spike firing patterns during locomotion and sleep. Purkinje cells discharge rhythmically during stepping, but this activity is highly variable across steps. We show that behavioral variables systematically influence the step-locked firing rate in a step-phase-dependent way, revealing a functional clustering of Purkinje cells. Furthermore, we find a pronounced disassociation between patterns of variability driven by the parallel and climbing fibers, as well as functional differences between cerebellar lobules. These results suggest that Purkinje cell activity not only represents step phase within each cycle, but is also shaped by behavior across steps, facilitating control of movement under dynamic conditions. During sleep, we observe an attenuation of both simple and complex spiking, relative to awake behavior. Although firing rates during slow wave sleep (SWS) and rapid eye movement sleep (REM) are similar, simple spike activity is highly regular in SWS, while REM is characterized by phasic increases and pauses in simple spiking. This phasic activity in REM is associated with pontine waves, which propagate into the cerebellar cortex and modulate both simple and complex spiking. Such a temporal coincidence between parallel and climbing fiber activity is known to drive plasticity at parallel fiber synapses; consequently, pontocerebellar waves may provide a mechanism for tuning synaptic weights in the cerebellum during active sleep.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Cerebellum; Purkinje cells; locomotion; sleep
Degree Grantor:California Institute of Technology
Division:Biology and Biological Engineering
Major Option:Computation and Neural Systems
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Siapas, Athanassios G.
Thesis Committee:
  • Perona, Pietro (chair)
  • Dickinson, Michael H.
  • Andersen, Richard A.
  • Sternberg, Paul W.
  • Siapas, Athanassios G.
Defense Date:18 November 2015
Record Number:CaltechTHESIS:12012015-143528464
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:12012015-143528464
DOI:10.7907/Z9G15XS8
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.neuron.2015.08.003DOIArticle adapted for ch. 3
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9302
Collection:CaltechTHESIS
Deposited By: Britton Sauerbrei
Deposited On:04 Dec 2015 23:21
Last Modified:18 May 2017 19:32

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