Auditory responses in the cochlear nucleus of awake mustached bats: precursors to spectral integration in the auditory midbrain

Robert A Marsh; Kiran Nataraj; Donald Gans; Christine V Portfors; Jeffrey J Wenstrup

doi:10.1152/jn.00634.2005

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Auditory responses in the cochlear nucleus of awake mustached bats: precursors to spectral integration in the auditory midbrain

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Auditory responses in the cochlear nucleus of awake mustached bats: precursors to spectral integration in the auditory midbrain

Robert A Marsh, Kiran Nataraj, Donald Gans, Christine V Portfors and Jeffrey J Wenstrup

Journal of neurophysiology, Vol.95(1), pp.88-105

01/2006

DOI: https://doi.org/10.1152/jn.00634.2005

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https://hdl.handle.net/2376/114982

PMCID: PMC1413954

PMID: 16148270

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Abstract

Acoustic Stimulation - methods

Action Potentials - physiology

Animals

Cochlear Nucleus - physiology

Pitch Perception - physiology

Brain Mapping

Wakefulness - physiology

Chiroptera - physiology

Mesencephalon - physiology

Nerve Net - physiology

Evoked Potentials, Auditory, Brain Stem - physiology

In the cochlear nucleus (CN) of awake mustached bats, single- and two-tone stimuli were used to examine how responses in major CN subdivisions contribute to spectrotemporal integrative features in the inferior colliculus (IC). Across CN subdivisions, the proportional representation of frequencies differed. A striking result was the substantial number of units tuned to frequencies <23 kHz. Across frequency bands, temporal response patterns, latency, and spontaneous discharge differed. For example, the 23- to 30-kHz representation, which comprises the fundamental of the sonar call, had an unusually high proportion of units with onset responses (39%) and low spontaneous rates (53%). Units tuned to 58-59 kHz, corresponding to the sharply tuned cochlear resonance, had slightly but significantly longer latencies than other bands. In units tuned to frequencies >30 kHz, 31% displayed a secondary excitatory peak, usually between 10 and 22 kHz. The secondary peak may originate in cochlear mechanisms for some units, but in others it may result from convergent input onto CN neurons. In 20% of units tested with two-tone stimuli, suppression of best frequency (BF) responses was tuned at least an octave below BF. These properties may underlie similar IC responses. However, other forms of spectral interaction present in IC were absent in CN: we found no facilitatory combination-sensitive interactions and very few combination-sensitive inhibitory interactions of the dominant IC type in which inhibition was tuned to 23-30 kHz. Such interactions arise above CN. Distinct forms of spectral integration thus originate at different levels of the ascending auditory pathway.

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Title: Auditory responses in the cochlear nucleus of awake mustached bats: precursors to spectral integration in the auditory midbrain
Creators: Robert A Marsh - Department of Neurobiology, Northeastern Ohio Universities College of Medicine, 4209 State Route 44, P.O. Box 95, Rootstown, OH 44272-0095, USA
Kiran Nataraj
Donald Gans
Christine V Portfors
Jeffrey J Wenstrup
Publication Details: Journal of neurophysiology, Vol.95(1), pp.88-105
Academic Unit: Office of the Provost
Publisher: United States
Grant note: R01 DC-00937 / NIDCD NIH HHS R01 DC000937 / NIDCD NIH HHS
Identifiers: 99900547786401842
Language: English
Resource Type: Journal article