Title

Neural auditory tuning in túngara frogs (Engystomops pustulosus)

Poster Number

26

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 lower 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 auditory sensitivity at the species’ peak vocalization frequencies. In some amphibians, extratympanic hearing structures, such as the lungs and body wall, serve as sensory organs for auditory stimuli. This research sought to verify the neural hearing sensitivity of túngara frogs by recording auditory evoked potential production in the torus semicircularis in response to a tone sweep. The recorded neural response matched the calling frequencies with peak sensitivity near 400 Hz with a secondary peak ranging from 2000-3000 Hz. However, characterizations of túngara eardrum sensitivity in our lab show peak response near the chuck frequency. Further research will attempt to elucidate the source of the tuning disparity. It is possible that túngara frogs may hear low frequency sounds disproportionately through their body walls, but past measurements of the mechanical sensitivity appear to belie the theory. Factors immanent to the calling environment may also influence sensitivity. First, with many competing species present in the mating area, túngara rely on the order of frequency presentation to prevent energetically wasteful inter-species mating. Second, túngara calls are made from the water where ovulating females swim with their eardrums at least partially submerged in water. This acoustic environment may produce significantly different aural sensitivity and explain the tuning disparity found when performing terrestrial measurements.

Location

DeRosa University Center, Ballroom

Start Date

25-4-2015 10:00 AM

End Date

25-4-2015 12:00 PM

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Apr 25th, 10:00 AM Apr 25th, 12:00 PM

Neural auditory tuning in túngara frogs (Engystomops pustulosus)

DeRosa University Center, Ballroom

Túngara frogs rely primarily on acoustic advertisement calls to find a mate. These calls consist of a lower 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 auditory sensitivity at the species’ peak vocalization frequencies. In some amphibians, extratympanic hearing structures, such as the lungs and body wall, serve as sensory organs for auditory stimuli. This research sought to verify the neural hearing sensitivity of túngara frogs by recording auditory evoked potential production in the torus semicircularis in response to a tone sweep. The recorded neural response matched the calling frequencies with peak sensitivity near 400 Hz with a secondary peak ranging from 2000-3000 Hz. However, characterizations of túngara eardrum sensitivity in our lab show peak response near the chuck frequency. Further research will attempt to elucidate the source of the tuning disparity. It is possible that túngara frogs may hear low frequency sounds disproportionately through their body walls, but past measurements of the mechanical sensitivity appear to belie the theory. Factors immanent to the calling environment may also influence sensitivity. First, with many competing species present in the mating area, túngara rely on the order of frequency presentation to prevent energetically wasteful inter-species mating. Second, túngara calls are made from the water where ovulating females swim with their eardrums at least partially submerged in water. This acoustic environment may produce significantly different aural sensitivity and explain the tuning disparity found when performing terrestrial measurements.