题目：Using an achiasmic human visual system to quantify the relationship between the fMRI BOLD signal and neural response

报告人：Prof. Bosco Tjan， Department of Psychology and Neuroscience Graduate Program; University of Southern California

时间：2014年12月16日 星期二 13:00-14:30

地点： 北京大学生命科学学院邓佑才报告厅

邀请人：方方

摘要: Quantifying the relationship between neural response and the BOLD signal had been difficult because neural response is multidimensional, and precisely measuring neural signals requires invasive techniques. Attempts to infer this relationship noninvasively from stimulus-evoked BOLD responses were frustrated by the complex nonlinearity between stimulus and neural response. In the low-level visual cortex of a human subject who was born without optic chiasm, we found evidence for the intermixing of two nearly identical but independent populations of neurons with non-overlapping receptive fields. With this unique in-vivo system, it was possible to double the local neural response, irrespective of its composition, by stimulating both of the associated receptive fields relative to stimulating just one. Our results from a series of contrast-summation experiments show that  BOLD response amplitude is proportional to the square root of the underlying neural response.