Cerebellar motor learning: when is cortical plasticity not enough?

Classical Marr-Albus theories of cerebellar learning employ only cortical sites of plasticity. However, tests of these theories using adaptive calibration of the vestibulo-ocular reflex (VOR) have indicated plasticity in both cerebellar cortex and the brainstem. To resolve this long-standing conflic...

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Autores principales:	John Porrill, Paul Dean
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2007
Materias:	Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/64f1c3f6b95648c29318698b540a21a3
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spelling	oai:doaj.org-article:64f1c3f6b95648c29318698b540a21a32021-11-25T05:41:01ZCerebellar motor learning: when is cortical plasticity not enough?1553-734X1553-735810.1371/journal.pcbi.0030197https://doaj.org/article/64f1c3f6b95648c29318698b540a21a32007-10-01T00:00:00Zhttps://doi.org/10.1371/journal.pcbi.0030197https://doaj.org/toc/1553-734Xhttps://doaj.org/toc/1553-7358Classical Marr-Albus theories of cerebellar learning employ only cortical sites of plasticity. However, tests of these theories using adaptive calibration of the vestibulo-ocular reflex (VOR) have indicated plasticity in both cerebellar cortex and the brainstem. To resolve this long-standing conflict, we attempted to identify the computational role of the brainstem site, by using an adaptive filter version of the cerebellar microcircuit to model VOR calibration for changes in the oculomotor plant. With only cortical plasticity, introducing a realistic delay in the retinal-slip error signal of 100 ms prevented learning at frequencies higher than 2.5 Hz, although the VOR itself is accurate up to at least 25 Hz. However, the introduction of an additional brainstem site of plasticity, driven by the correlation between cerebellar and vestibular inputs, overcame the 2.5 Hz limitation and allowed learning of accurate high-frequency gains. This "cortex-first" learning mechanism is consistent with a wide variety of evidence concerning the role of the flocculus in VOR calibration, and complements rather than replaces the previously proposed "brainstem-first" mechanism that operates when ocular tracking mechanisms are effective. These results (i) describe a process whereby information originally learnt in one area of the brain (cerebellar cortex) can be transferred and expressed in another (brainstem), and (ii) indicate for the first time why a brainstem site of plasticity is actually required by Marr-Albus type models when high-frequency gains must be learned in the presence of error delay.John PorrillPaul DeanPublic Library of Science (PLoS)articleBiology (General)QH301-705.5ENPLoS Computational Biology, Vol 3, Iss 10, Pp 1935-1950 (2007)
institution	DOAJ
collection	DOAJ
language	EN
topic	Biology (General) QH301-705.5
spellingShingle	Biology (General) QH301-705.5 John Porrill Paul Dean Cerebellar motor learning: when is cortical plasticity not enough?
description	Classical Marr-Albus theories of cerebellar learning employ only cortical sites of plasticity. However, tests of these theories using adaptive calibration of the vestibulo-ocular reflex (VOR) have indicated plasticity in both cerebellar cortex and the brainstem. To resolve this long-standing conflict, we attempted to identify the computational role of the brainstem site, by using an adaptive filter version of the cerebellar microcircuit to model VOR calibration for changes in the oculomotor plant. With only cortical plasticity, introducing a realistic delay in the retinal-slip error signal of 100 ms prevented learning at frequencies higher than 2.5 Hz, although the VOR itself is accurate up to at least 25 Hz. However, the introduction of an additional brainstem site of plasticity, driven by the correlation between cerebellar and vestibular inputs, overcame the 2.5 Hz limitation and allowed learning of accurate high-frequency gains. This "cortex-first" learning mechanism is consistent with a wide variety of evidence concerning the role of the flocculus in VOR calibration, and complements rather than replaces the previously proposed "brainstem-first" mechanism that operates when ocular tracking mechanisms are effective. These results (i) describe a process whereby information originally learnt in one area of the brain (cerebellar cortex) can be transferred and expressed in another (brainstem), and (ii) indicate for the first time why a brainstem site of plasticity is actually required by Marr-Albus type models when high-frequency gains must be learned in the presence of error delay.
format	article
author	John Porrill Paul Dean
author_facet	John Porrill Paul Dean
author_sort	John Porrill
title	Cerebellar motor learning: when is cortical plasticity not enough?
title_short	Cerebellar motor learning: when is cortical plasticity not enough?
title_full	Cerebellar motor learning: when is cortical plasticity not enough?
title_fullStr	Cerebellar motor learning: when is cortical plasticity not enough?
title_full_unstemmed	Cerebellar motor learning: when is cortical plasticity not enough?
title_sort	cerebellar motor learning: when is cortical plasticity not enough?
publisher	Public Library of Science (PLoS)
publishDate	2007
url	https://doaj.org/article/64f1c3f6b95648c29318698b540a21a3
work_keys_str_mv	AT johnporrill cerebellarmotorlearningwheniscorticalplasticitynotenough AT pauldean cerebellarmotorlearningwheniscorticalplasticitynotenough
_version_	1718414520221696000

Cerebellar motor learning: when is cortical plasticity not enough?

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