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Zoological Research
Kunming Institute of Zoology, Chinese Academy of Sciences
ISSN: 2095-8137
Vol. 33, No. 5, 2012, pp. 498-502
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Bioline Code: zr12078
Full paper language: English
Document type: Research Article
Document available free of charge
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Zoological Research, Vol. 33, No. 5, 2012, pp. 498-502
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Aging affects early stage direction selectivity of MT cells in rhesus monkeys
LIANG, Zhen; CHEN, Yue-Ming; MENG, Xue; WANG, Yi; ZHOU, Bao-Zhuo; XIE, Ying-Ying & HE, Wen-Sheng
Abstract
The middle temporal area (MT/V5) plays an important role in motion processing. Neurons in this area
have a strongly selective response to the moving direction of objects and as such, the selectivity of MT neurons was
proposed to be a neural mechanism for the perception of motion. Our previous studies have found degradation in
direction selectivity of MT neurons in old monkeys, but this direction selectivity was calculated during the whole
response time and the results were not able to uncover the mechanism of motion perception over a time course.
Furthermore, experiments have found that direction selectivity was enhanced by attention at a later stage. Therefore, the
response should be excluded in experiments with anesthesia. To further characterize the neural mechanism over a time
course, we investigated the age-related changes of direction selectivity in the early stage by comparing the proportions of
direction selective MT cells in old and young macaque monkeys using in vivo single-cell recording techniques. Our
results show that the proportion of early-stage-direction-selective cells is lower in old monkeys than in young monkeys,
and that the early stage direction bias (esDB) of old MT cells decreased relative to young MT cells. Furthermore, the
proportion of MT cells having strong early stage direction selectivity in old monkeys was decreased. Accordingly, the
functional degradation in the early stage of MT cells may mediate perceptual declines of old primates in visual motion
tasks.
Keywords
Early stage direction selectivity; Middle temporal area; Aging
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