The voltage sensitive dye (VSD) is a molecule that, once bound to the external surface of cell membranes, acts as a molecular transducer transforming changes in membrane potential into optical signals (changes in absorption or emitted fluorescence). The amplitude of VSD signals are directly correlated with changes in membrane potential.

The VSD (Di-4Anepps; Molecular Probes) signals coming from acute cerebellar slices are collected with a fast CCD camera (up to 1.5 KhZ sampling frequency; Scimedia).

We use VSD imaging to follow the propagation of excitation and inhibition into the granular and molecular layers after the stimulation of the mossy fiber bundle. The complex dynamics of these events could be described with a spatial resolution that other electrophysiology techniques don’t allow.