Biology Reference
In-Depth Information
Chapter 5
S
YNAPTIC
P
LASTICITY AND
M
OTOR
L
EARNING
IN THE
C
EREBELLUM
Shun Tsuruno and Tomoo Hirano
Department of Biophysics, Kyoto University, Japan
A
BSTRACT
The cerebellum plays a key role in motor learning. Since Marr and Albus proposed
the perceptron model of cerebellar cortex, extensive study has been performed to clarify
the mechanism of motor learning. The cerebellar long-term depression (LTD) is a type of
synaptic plasticity occurring at the parallel fiber - Purkinje cell synapses, which was
predicted by Albus and has been regarded as a cellular basis of motor learning. Not only
its involvement in motor learning but also its regulation mechanisms at a molecular level
have been clarified. On the other hand, other forms of synaptic plasticity have been
reported in the cerebellum. Long-tem potentiation (LTP) and LTD occur at both
excitatory and inhibitory synapses in the cortex and also in the cerebellar nuclei. Their
molecular mechanisms and implication in motor learning have also been studied.
In this article, we begin by reviewing researches on the regulatory molecular
mechanisms of the cerebellar LTD. Then, we turn to other forms of synaptic plasticity.
Finally, we summarize the involvement of cerebellar synaptic plasticity in several motor
learning tasks by reviewing studies on animals with surgical lesion, chemical inactivation
or genetic manipulation of a specific region of the cerebellar circuit.
I
NTRODUCTION
The cerebellum is involved in motor control and motor learning. Recent progress in brain
imaging techniques has revealed that the cerebellum is also involved in cognitive functions
such as processing of language [1,2]. The cerebellum is composed of cortex and nuclei [3].
Five types of neurons, Purkinje cells, granule cells, Golgi cells, basket cells and stellate cells,
