Voltage-Sensitive Dye Imaging of Cortical Dynamics

Voltage-sensitive dyes can be topically applied to the surface of the brain in order to label membranes in the supragranular layers of the neocortex. Fluorescence signals from voltage-sensitive dyes in vivo correlate linearly with membrane potential of excitatory layer 2/3 neurons with millisecond temporal resolution and with a spatial resolution resolving single cortical columns. Voltage-sensitive dye imaging across large cortical areas in awake behaving mice reveals interactions between somatosensory and motor cortex that depend strongly on behavioral state. The recent development of genetically encoded voltage-sensitive fluorescent proteins will likely help towards long-term measurements of the electrical activity of specific cell types.