title: [Aging affects early stage direction selectivity of MT cells in rhesus monkeys].
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.
authors.affiliation: Department of Bio-Medical Engineering, Anhui Medical University, Hefei Anhui 230032, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liang
authors.forename: Yue-Ming
authors.initials: YM
authors.lastname: Chen
authors.forename: Xue
authors.initials: X
authors.lastname: Meng
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Bao-Zhuo
authors.initials: BZ
authors.lastname: Zhou
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Xie
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: He
mesh_terms: D000375:Aging / Q000502:physiology / Q000523:psychology*; D000818:Animals; D004195:Disease Models, Animal; D006801:Humans; D008253:Macaca mulatta / Q000502:physiology*; D009038:Motion; D009039:Motion Perception; D009046:Motor Neurons / Q000502:physiology*