The goal of this project is to develop, in the P.I.'s laboratory, techniques for whole cell patch clamp recording from neurons in the inferior colliculus (IC) of awake echolocating bats. Pilot data show that such studies are feasible, and suggest that the use of patch clamp recording to measure sound-evoked EPSCs and IPSCs in vivo will yield a wealth of new information on signal processing mechanisms in the auditory midbrain. Initially this technique will be used to investigate the hypothesis that IC cells have long periods of subthreshold facilitation or inhibition following sound- evoked discharge. Patch clamp recording is the best method available for studying subthreshold synaptic processes. Neurons remain healthy longer and the signal-to-noise ration is better than when they are impaled with intracellular microelectrodes. These factors are important when recording from small neurons such as those in the IC, and when measuring stimulus-evoked responses where lengthy testing of different variables is necessary. The in vivo patch clamp technique is an essential addition to the anatomical, electrophysiological and neuropharmacological methods currently employed by the P.I. because it will, for the first time, make natural subthreshold synaptic events amenable to investigation.
