Document Detail


Cerebellar flocculus and paraflocculus Purkinje cell activity during circular pursuit in monkey.
MedLine Citation:
PMID:  10634849     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Responses from 69 Purkinje cells in the flocculus and paraflocculus of two rhesus monkeys were studied during smooth pursuit of targets moving along circular trajectories and compared with responses during sinusoidal pursuit and fixation. A variety of interesting responses was observed during circular pursuit. Although some neurons fired most strongly in a single preferred direction during clockwise (CW) and counterclockwise (CCW) pursuit, others had directional preferences that changed with rotation direction. Some of these neurons showed similar modulation amplitudes during CW and CCW pursuit, whereas other neurons showed a preference for a particular rotation direction. Response specificity also was observed during sinusoidal pursuit. Some neurons showed responses that were much stronger during centrifugal pursuit, others showed a preference for centripetal pursuit, and still others showed responses during both centripetal and centrifugal motion. Differences in preferred response direction were sometimes observed for centripetal versus centrifugal pursuit. CW/CCW and centrifugal/centripetal preferences were not explained by a breakdown in component additivity. That is, modulations in firing rate during pursuit along a circular trajectory equaled the sum of modulations during horizontal and vertical sinusoidal components as well as for diagonal components. Instead all responses were well fit by a model that expressed the instantaneous firing rate of each neuron as a multilinear function of the two-dimensional position and velocity of the eye. This model generalized well to performance at different sinusoidal frequencies. It did somewhat less well for responses during fixation, suggesting some separation in the neural mechanisms of dynamic and static positioning. The model indicates that position sensitivity accounted for approximately 36% of the modulation during circular pursuit, and velocity sensitivity accounted for approximately 64%. When position and velocity sensitivity vectors were aligned, responses were simpler and modulations were similar during CW versus CCW pursuit. In contrast, when these vectors pointed in different directions, response complexity increased. Nonaligned position and velocity influences tended to reinforce during circular pursuit in one direction and to cancel each other during pursuit in the opposite direction. They also tended to produce response differences during centripetal versus centrifugal sinusoidal pursuit. The distinct roles played by position and velocity in shaping Purkinje cell responses are compatible with the control signals required to generate smooth pursuit along circular and other two-dimensional trajectories.
Authors:
H C Leung; M Suh; R E Kettner
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of neurophysiology     Volume:  83     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2000 Jan 
Date Detail:
Created Date:  2000-02-16     Completed Date:  2000-02-16     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  13-30     Citation Subset:  IM    
Affiliation:
Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Brain Mapping
Calibration
Cerebellum / physiology*
Conditioning, Operant
Macaca mulatta
Male
Purkinje Cells / physiology*
Pursuit, Smooth / physiology*
Reaction Time
Reward
Rotation
Grant Support
ID/Acronym/Agency:
P50 MH-48185/MH/NIMH NIH HHS; T32 DC-0015-13/DC/NIDCD NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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