Title

Auditory tuning disparities in túngara frogs (Engystomops pustulosus) - comparing hearing pathways through midbrain recording

Poster Number

8

Lead Author Major

Biological Sciences

Format

Poster Presentation

Faculty Mentor Name

Marcos Gridi-Papp

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Túngara frogs rely primarily on acoustic advertisement calls to find a mate. These calls consist of a low frequency "whine" from 400- 900 Hz, essential for species recognition, followed by an optional higher frequency "chuck" near 2500 Hz. In most species of frogs, the hearing pathway is tuned to have maximal sensitivity at the species’ peak vocalization frequencies, however characterizations of túngara frog eardrum sensitivity in our lab show peak response near the chuck frequency. We examined the neural hearing sensitivity of túngara frogs by recording auditory evoked potentials at the torus semicircularis in response to a tone sweep. The recorded neural response was consonant with reports in the literature - peak sensitivity at low frequencies (below that of the whine) and a secondary peak with reduced sensitivity in the chuck range. In small amphibians, other body parts besides the eardrum, such as the body wall and the arms, can also serve as auditory receptors. This hypothesis is supported by preliminary results in which túngara frogs hear low frequencies even when a thick coat of vaseline dampens their eardrum bulging. However, laser vibrometry measurements of the body wall and arms have failed to detect any considerable vibration response in the 200-700 Hz range, therefore the pathway for reception of low frequencies remains unidentified. This puzzling mismatch among the tuning of the eardrums, brain and male calls is uncommon in frogs and its explanation may reveal a novel auditory mechanism.

Location

DeRosa University Center, Ballroom

Start Date

30-4-2016 1:30 AM

End Date

30-4-2016 3:30 PM

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Apr 30th, 1:30 AM Apr 30th, 3:30 PM

Auditory tuning disparities in túngara frogs (Engystomops pustulosus) - comparing hearing pathways through midbrain recording

DeRosa University Center, Ballroom

Túngara frogs rely primarily on acoustic advertisement calls to find a mate. These calls consist of a low frequency "whine" from 400- 900 Hz, essential for species recognition, followed by an optional higher frequency "chuck" near 2500 Hz. In most species of frogs, the hearing pathway is tuned to have maximal sensitivity at the species’ peak vocalization frequencies, however characterizations of túngara frog eardrum sensitivity in our lab show peak response near the chuck frequency. We examined the neural hearing sensitivity of túngara frogs by recording auditory evoked potentials at the torus semicircularis in response to a tone sweep. The recorded neural response was consonant with reports in the literature - peak sensitivity at low frequencies (below that of the whine) and a secondary peak with reduced sensitivity in the chuck range. In small amphibians, other body parts besides the eardrum, such as the body wall and the arms, can also serve as auditory receptors. This hypothesis is supported by preliminary results in which túngara frogs hear low frequencies even when a thick coat of vaseline dampens their eardrum bulging. However, laser vibrometry measurements of the body wall and arms have failed to detect any considerable vibration response in the 200-700 Hz range, therefore the pathway for reception of low frequencies remains unidentified. This puzzling mismatch among the tuning of the eardrums, brain and male calls is uncommon in frogs and its explanation may reveal a novel auditory mechanism.