The Optimal Fitting Model For Aging-related Receptive Field Size Curve Of Macaque V1Neurons

Visual function in humans degrades during the early stage of senescence beginning from middle50s to60s,it is more obvious in the aging process.Generally,it may derive from the general decline of cortex inhibition in the aging process, which destroys the balance between "excitation and inhibition" system in the brain. The fitting model of the receptive field size curve is important for basic visual information processing.To date, the optimal fitting model is not clear for receptive field size curve of primary visual cortex neurons during different age groups in monkeys.To address this issue, firstly, we carried out extracellular single-unit studies of the receptive field properties of cells in the primary visual cortex (area V1) in young and old rhesus (Macaca mulatta) monkeys. By IGOR, we obtain the original data of receptive field size curve. Secondly, we use the existing models of Gaussian, DOG (subtractive) and a normalization (divisive) model to fit the data respectively. All fitting procedures were done with the1stopt (First Optimization). Based on the three models, we write the corresponding function, and select the appropriate fitting algorithm.First step, we choose a group data of receptive field size of young or old randomly, fitting the obtained data under three models, then we can get different kinds of chart. Second step, we use1stopt to analyze each group one by one, and record their statistical data. The last step, we make analysis for the statistical data, especially the fitting goodness.The most important of all, finally,we found clear indications:The fitting goodness of DOG model has a high degree during different age groups in rhesus monkeys and it can reflect that DOG model has good adaptability and flexibility.In addition, we also can draw the conclusion thaf:In the aging process, the turning curvature of receptive field size curve of V1cells changes obviously, and the surround suppression of the receptive field of V1cells also decreases clearly.This work will contribute to an understanding of the relationship of receptive field size curve,which formed by the irritation of the central excitement region and the surround suppression region in different age groups,and these results provide new insight into the changes caused by the effects of aging on the strength of surround suppression in the visual system. Moreover, it is worth noting that the aging-related retinal changes in humans,it seems to be more significant than those in monkeys.