Voltage-Sensitive Dye Imaging of Cortical Function In Vivo

Voltage-sensitive dye imaging (VSDI) is the optical interrogation of transmembrane voltage using an exogenous membrane-bound probe. When bulk-applied to intact tissue, voltage-sensitive dyes allow the measurement at high temporal and spatial resolution of subthreshold population membrane potential dynamics in regions of interest of arbitrary size and shape. This is particularly useful in vivo for mapping of input patterns to surface brain structures in order to study neuronal integration at the population level. This chapter provides an introduction to the use of VSDI in vivo. The first half consists of a discussion of the mechanism of action of optical voltage probes and the resulting implications for the interpretation of VSDI data, and offers a perspective on useful future applications and improvements. The second half includes a detailed protocol for VSDI in the barrel cortex of the anesthetized mouse, followed by further notes on practical details of the method.