Echo duration selectivity of the bat varies with pulse-echo amplitude difference.

During hunting, insectivorous bats progressively decrease the pulse duration, pulse amplitude and pulse-echo gap as they search, approach and finally intercept the prey. Our earlier study shows that echo duration selectivity of most neurons in the central nucleus of the inferior colliculus of Eptesicus fuscus improves with decreasing pulse duration and pulse-echo gap. In this study, we show that most collicular neurons discharged maximally to a best echo duration using three biologically relevant pulse-echo pairs as stimuli. The echo duration selectivity of these collicular neurons improves with decreasing pulse duration, pulse-echo gap and amplitude difference. This improvement of echo duration selectivity with variation in pulse-echo parameters throughout a target approaching sequence would certainly facilitate prey capture.