A measure of extracellular unit responses to repeated stimulation applied to observations of the time course of olfactory responses.

A technique for measurement of small samples of unit behavior during regularly repeated stimulation is described. A correlation-based measure was computed over two successive stimulus presentation by summing the products of spike counts for corrsponding time bins and normalizing to the number of bins and the number of spike counts during the two stimulus presentations. This measure was combined with the mean frequency of spike occurrence during the stimulus presentation to give a characterization of neuronal activity sensitive to changes in both strength of temporal patterns and mean frequency. Examples are given of olfactory responsive neurons with comparison of measurement techniques. The time course of the response to odor of neurons recorded under urethane anesthesia from the olfactory bulb and the lateral hypothalamus was studied. By both simple mean frequency measures and the measures proposed in this study, the neurons recorded from the lateral hypothalamus underwent more rapid temporal decrements in the odor response.