High Frequency Responsiveness in Rodents at the Level of the Inferior Colliculus

PREVIOUS work on the cochlear microphonic (CM) response of three species of rodents showed a second peak of sensitivity coinciding in frequency with the ultrasound emitted in each species¹. It was indicated that the microphonic response did not necessarily represent hearing, but Sewell's² finding that Apodemus can hear the ultrasonic cries of its young makes an investigation into the neural response to ultrasound seem necessary. The gross inferior collicular (IC) response of the same three species, Apodemus sylvaticus Linnaeus, Clethrionomys glareolus Schreber and Meriones shawi Rozet, has now been studied together with the CM response of the same individuals.