Abstract
Voltage-sensitive dye imaging (VSDI) measures local changes in pooled membrane potentials, simultaneously from dozens of square millimeters of cortex, with millisecond temporal resolution and spatial resolution sufficient to resolve cortical orientation columns. To better understand the quantitative relationship between the VSDI signal and spiking activity of a local neural population, we compared visual responses measured from V1 of behaving monkeys using VSDI and single-unit electrophysiology. We found large and systematic differences between response properties obtained with these two techniques. We then used these results to develop a simple computational model of the quantitative relationship between the average VSDI signal and local spiking activity. In this talk I will describe the model and demonstrate how it can be used to interpret top-down attentional modulations observed using VSDI in macaque V1.