title: An Overrepresentation of High Frequencies in the Mouse Inferior Colliculus Supports the Processing of Ultrasonic Vocalizations.
abstract: Mice are of paramount importance in biomedical research and their vocalizations are a subject of interest for researchers across a wide range of health-related disciplines due to their increasingly important value as a phenotyping tool in models of neural, speech and language disorders. However, the mechanisms underlying the auditory processing of vocalizations in mice are not well understood. The mouse audiogram shows a peak in sensitivity at frequencies between 15-25 kHz, but weaker sensitivity for the higher ultrasonic frequencies at which they typically vocalize. To investigate the auditory processing of vocalizations in mice, we measured evoked potential, single-unit, and multi-unit responses to tones and vocalizations at three different stages along the auditory pathway: the auditory nerve and the cochlear nucleus in the periphery, and the inferior colliculus in the midbrain. Auditory brainstem response measurements suggested stronger responses in the midbrain relative to the periphery for frequencies higher than 32 kHz. This result was confirmed by single- and multi-unit recordings showing that high ultrasonic frequency tones and vocalizations elicited responses from only a small fraction of cells in the periphery, while a much larger fraction of cells responded in the inferior colliculus. These results suggest that the processing of communication calls in mice is supported by a specialization of the auditory system for high frequencies that emerges at central stations of the auditory pathway.
authors.affiliation: Ear Institute, University College London, 332 Grays Inn Road, London, WC1X 8EE, United Kingdom.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Garcia-Lazaro
authors.affiliation: Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia, 30322, United States of America.
authors.forename: Kathryn N
authors.initials: KN
authors.lastname: Shepard
authors.affiliation: Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia, 30322, United States of America.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Miranda
authors.affiliation: Department of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia, 30322, United States of America.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Liu
authors.affiliation: Ear Institute, University College London, 332 Grays Inn Road, London, WC1X 8EE, United Kingdom.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Lesica
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D003056:Cochlear Nerve / Q000502:physiology; D017626:Cochlear Nucleus / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D007245:Inferior Colliculi / Q000502:physiology*; D051379:Mice; D000069453:Ultrasonic Waves; D014828:Vocalization, Animal / Q000502:physiology*