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Long-term depression and other synaptic plasticity in the cerebellum.

Hirano T - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2013)

Bottom Line: LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate.In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning.A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan. thirano@neurosci.biophys.kyoto-u.ac.jp

ABSTRACT
Cerebellar long-term depression (LTD) is a type of synaptic plasticity and has been considered as a critical cellular mechanism for motor learning. LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate. Molecular induction mechanism of LTD has been intensively studied using culture and slice preparations, which has revealed critical roles of Ca(2+), protein kinase C and endocytosis of AMPA-type glutamate receptors. Involvement of a large number of additional molecules has also been demonstrated, and their interactions relevant to LTD mechanisms have been studied. In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning. However, motor learning could occur with impaired LTD. A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.

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Main cerebellar cortical circuits. LTD occurs at parallel fiber-Purkinje cell synapses.
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fig01: Main cerebellar cortical circuits. LTD occurs at parallel fiber-Purkinje cell synapses.

Mentions: The organization of the cerebellum reflects its involvement in motor control. The cerebellum consists of cortex and nuclei, and major inputs to the cortex come from the spinal cord, pons etc. through mossy fibers. Mossy fibers send excitatory glutamatergic outputs to granule neurons, which in turn transmit excitatory synaptic information to Purkinje cells (Fig. 1). Cerebellar granule cells are most numerous neurons in the whole brain. The cell body of a granule cell is located in the granular layer, and extends an axon to the molecular layer, where it bifurcates to form parallel fibers. Purkinje cell dendrites show extensive branching in the molecular layer and receive >150,000 parallel fiber synaptic inputs. Purkinje cells are the sole output neurons in the cortex. Its axon projects to a cerebellar or vestibular nucleus, and inhibits neurons through secretion of γ-amino butyric acid (GABA) there. A Purkinje cell receives another type of excitatory synaptic inputs from a neuron in an inferior olivary nucleus through a climbing fiber. A single climbing fiber forms >300 synapses on a Purkinje cell, and provides powerful excitatory drive. In contrast, each parallel fiber forms only one or a few synapses on a Purkinje cell, although the number of parallel fibers innervating a Purkinje cell is huge. This synaptic organization is maintained throughout the cerebellar cortex.1,2)


Long-term depression and other synaptic plasticity in the cerebellum.

Hirano T - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2013)

Main cerebellar cortical circuits. LTD occurs at parallel fiber-Purkinje cell synapses.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3722574&req=5

fig01: Main cerebellar cortical circuits. LTD occurs at parallel fiber-Purkinje cell synapses.
Mentions: The organization of the cerebellum reflects its involvement in motor control. The cerebellum consists of cortex and nuclei, and major inputs to the cortex come from the spinal cord, pons etc. through mossy fibers. Mossy fibers send excitatory glutamatergic outputs to granule neurons, which in turn transmit excitatory synaptic information to Purkinje cells (Fig. 1). Cerebellar granule cells are most numerous neurons in the whole brain. The cell body of a granule cell is located in the granular layer, and extends an axon to the molecular layer, where it bifurcates to form parallel fibers. Purkinje cell dendrites show extensive branching in the molecular layer and receive >150,000 parallel fiber synaptic inputs. Purkinje cells are the sole output neurons in the cortex. Its axon projects to a cerebellar or vestibular nucleus, and inhibits neurons through secretion of γ-amino butyric acid (GABA) there. A Purkinje cell receives another type of excitatory synaptic inputs from a neuron in an inferior olivary nucleus through a climbing fiber. A single climbing fiber forms >300 synapses on a Purkinje cell, and provides powerful excitatory drive. In contrast, each parallel fiber forms only one or a few synapses on a Purkinje cell, although the number of parallel fibers innervating a Purkinje cell is huge. This synaptic organization is maintained throughout the cerebellar cortex.1,2)

Bottom Line: LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate.In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning.A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan. thirano@neurosci.biophys.kyoto-u.ac.jp

ABSTRACT
Cerebellar long-term depression (LTD) is a type of synaptic plasticity and has been considered as a critical cellular mechanism for motor learning. LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate. Molecular induction mechanism of LTD has been intensively studied using culture and slice preparations, which has revealed critical roles of Ca(2+), protein kinase C and endocytosis of AMPA-type glutamate receptors. Involvement of a large number of additional molecules has also been demonstrated, and their interactions relevant to LTD mechanisms have been studied. In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning. However, motor learning could occur with impaired LTD. A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.

Show MeSH
Related in: MedlinePlus