Document Detail

Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey.
MedLine Citation:
PMID:  10022498     Owner:  NLM     Status:  MEDLINE    
We examined the nature and the selectivity of the motion deficits produced by lesions of extrastriate areas MT and MST. Lesions were made by injecting ibotenic acid into the representation of the left visual field in two macaque monkeys. The monkeys discriminated two stimuli that differed either in stimulus direction or orientation. Direction and orientation discrimination were assessed by measuring thresholds with gratings and random-dots placed in the intact or lesioned visual fields. At the start of behavioral testing, we found pronounced, motion-specific deficits in thresholds for all types of moving stimuli, including pronounced elevations in contrast thresholds and in signal-to-noise thresholds measured with moving gratings, as well as deficits in direction range thresholds and motion coherence measured with random-dot stimuli. In addition, the accuracy of direction discrimination was reduced at smaller spatial displacements (i.e. step sizes), suggesting an increase in spatial scale of the residual directional mechanism. Subsequent improvements in thresholds were seen with all motion stimuli, as behavioral training progressed, and these improvements occurred only with extensive behavioral testing in the lesioned visual field. These improvements were particularly pronounced for stimuli not masked by noise. On the other hand, deficits in the ability to extract motion from noisy stimuli and in the accuracy of direction discrimination persisted despite extensive behavioral training. These results demonstrate the importance of areas MT and MST for the perception of motion direction, particularly in the presence of noise. In addition, they provide evidence for the importance of behavioral training for functional recovery after cortical lesions. The data also strongly support the idea of functional specialization of areas MT and MST for motion processing.
K Rudolph; T Pasternak
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cerebral cortex (New York, N.Y. : 1991)     Volume:  9     ISSN:  1047-3211     ISO Abbreviation:  Cereb. Cortex     Publication Date:    1999 Jan-Feb
Date Detail:
Created Date:  1999-04-22     Completed Date:  1999-04-22     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9110718     Medline TA:  Cereb Cortex     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  90-100     Citation Subset:  IM; S    
Department of Neurobiology & Anatomy and Center for Visual Science, University of Rochester, NY 14642, USA.
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MeSH Terms
Discrimination (Psychology) / physiology
Macaca nemestrina
Magnetic Resonance Imaging
Motion Perception / physiology*
Reproducibility of Results
Sensory Thresholds / physiology*
Time Factors
Visual Cortex / physiology*
Visual Fields / physiology*
Grant Support

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

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