Concepts in imaging and microscopy - Imaging membrane potential with voltage-sensitive dyes

Membrane potential can be measured optically using a variety of molecular p robes. These measurements can be useful in studying function at the level o f an individual cell, for determining how groups of neurons generate a beha vior, and for studying the correlated behavior of populations of neurons. E xamples of the three kinds of measurements are presented. The signals obtai ned from these measurements are generally small. Methodological considerati ons necessary to optimize the resulting signal-to-noise ratio are discussed .