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Ratio of Inhibited-to-Activated Pallidal Neurons Decreases Dramatically During Passive Limb Movement in the MPTP-Treated Monkey

Ratio of Inhibited-to-Activated Pallidal Neurons Decreases Dramatically During Passive Limb... Abstract Mink advanced the hypothesis in 1996 that the role of the basal ganglia (BG) is primarily one of focused selection; the encouragement of motor mechanisms inducing a desired movement and the inhibition of competing mechanisms. This would imply, in normal subjects, a ratio of inhibited-to-activated (I/A) movement-related globus pallidus pars internalis (GPi) neurons <1 and a drastic decrease of this ratio in the parkinsonian state. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication should therefore decrease the specificity of the response of this neuronal population. To test this working hypothesis we studied the activity of GPi neurons in response to passive limb movement in the normal and the parkinsonian monkey. Extracellular unit recordings monitored any correlation between passive limb movements and eventual modifications of the neuronal activity of the GPi in two calm, awake, and drug naive monkeys ( Macaca fascicularis ) before and after MPTP intoxication. In the normal animal, arm- and leg-related neurons were located in clusters in the medial part of the GPi. The I/A ratio was 0.22. Most GPi cells were linked to a single joint. In the MPTP-treated monkey, the number of movement-related neurons increased, the I/A ratio dropped significantly to 0.03, and most responding cells were linked to several joints. These data, which cannot be explained by the classic “box” model, endorse Mink's hypothesis. Footnotes Address for reprint requests: T. Boraud, Basal Gang, CNRS UMR 5543, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Copyright © 2000 The American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Neurophysiology The American Physiological Society

Ratio of Inhibited-to-Activated Pallidal Neurons Decreases Dramatically During Passive Limb Movement in the MPTP-Treated Monkey

Boraud, T.; Bezard, E.; Bioulac, B.; Gross, C. E.
Journal of Neurophysiology , Volume 83 (3): 1760 – Mar 1, 2000
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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0022-3077
eISSN
1522-1598
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Abstract

Abstract Mink advanced the hypothesis in 1996 that the role of the basal ganglia (BG) is primarily one of focused selection; the encouragement of motor mechanisms inducing a desired movement and the inhibition of competing mechanisms. This would imply, in normal subjects, a ratio of inhibited-to-activated (I/A) movement-related globus pallidus pars internalis (GPi) neurons <1 and a drastic decrease of this ratio in the parkinsonian state. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication should therefore decrease the specificity of the response of this neuronal population. To test this working hypothesis we studied the activity of GPi neurons in response to passive limb movement in the normal and the parkinsonian monkey. Extracellular unit recordings monitored any correlation between passive limb movements and eventual modifications of the neuronal activity of the GPi in two calm, awake, and drug naive monkeys ( Macaca fascicularis ) before and after MPTP intoxication. In the normal animal, arm- and leg-related neurons were located in clusters in the medial part of the GPi. The I/A ratio was 0.22. Most GPi cells were linked to a single joint. In the MPTP-treated monkey, the number of movement-related neurons increased, the I/A ratio dropped significantly to 0.03, and most responding cells were linked to several joints. These data, which cannot be explained by the classic “box” model, endorse Mink's hypothesis. Footnotes Address for reprint requests: T. Boraud, Basal Gang, CNRS UMR 5543, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Copyright © 2000 The American Physiological Society

Journal

Journal of Neurophysiology – The American Physiological Society

Published: Mar 1, 2000

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