Temporal response properties to second-order visual stimuli in the LGN of cats  

作　　者：XU PengJing YE Xiang ZHOU Yifeng 

机构地区：[1]Vision Research Lab, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China [2]State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China

出　　处：《Chinese Science Bulletin》2007年第16期2233-2239,共7页

摘　　要：Visual stimuli occurring naturally are rich in instances of objects delineated from the backgrounds only by differences in luminance,which is called first-order stimuli,as well as those defined by differences of contrast or texture,referred to as second-order stimuli. The neuronal mechanism for processing second-order stimuli is still unclear. In this study,we compared the responses of cat LGN (lateral geniculate nucleus) cells to second-order stimuli at five temporal frequencies to their responses to first-order stimuli. Our results showed that most LGN cells can be evoked by second-order stimuli,and their firing rates to second-order stimuli decreased relative to first-order stimuli as temporal frequency increased from 0.5 to 8 Hz; moreover the ratio of a nonlinear to linear factor had a higher value in the responses to second-order stimuli than to first-order stimuli. We also found that the responses of Y-cells to second-order stimuli were significantly higher than the responses of X-cells,suggesting the Y-cells have a more important role in the processing of second-order stimuli. All these results reveal that first-order and second-order signals might be processed in separate 'streams' of the visual sys-tem.Visual stimuli occurring naturally are rich in instances of objects delineated from the backgrounds only by differences in luminance, which is called first-order stimuli, as well as those defined by differences of contrast or texture, referred to as second-order stimuli. The neuronal mechanism for processing second-order stimuli is still unclear. In this study, we compared the responses of cat LGN （lateral geniculate nucleus） cells to second-order stimuli at five temporal frequencies to their responses to first-order stimuli. Our results showed that most LGN cells can be evoked by second-order stimuli, and their firing rates to second-order stimuli decreased relative to first-order stimuli as temporal frequency increased from 0.5 to 8 Hz; moreover the ratio of a nonlinear to linear factor had a higher value in the responses to second-order stimuli than to first-order stimuli. We also found that the responses of Y-cells to second-order stimuli were significantly higher than the responses of X-cells, suggesting the Y-cells have a more important role in the processing of second-order stimuli. All these results reveal that first-order and second-order signals might be processed in separate ‘streams＇ of the visual system.

关 键 词：猫 视觉 一阶激励 二阶激励 瞬时响应 亮度 

分 类 号：Q436[生物学—生理学]