Mechanisms of Auditory Grouping in Cope’s Gray Treefrog

Abstract

Event Abstract Back to Event Mechanisms of Auditory Grouping in Cope’s Gray Treefrog Katrina Schrode1* and Mark A. Bee1, 2 1 University of Minnesota, Graduate Program in Neuroscience, United States 2 University of Minnesota, Department of Ecology, Evolution, and Behavior, United States Many animals communicate acoustically in large, social aggregations, where the overlapping signals of conspecifics make it difficult to follow a particular signal. Part of the solution to this problem requires listeners to integrate or group sound elements by their sources. Humans use spectral proximity and other acoustic properties as auditory grouping cues, but less is known about the mechanisms other animals may use. Here, we tested the hypothesis that females of Cope’s gray treefrog (Hyla chrysoscelis) use spectral proximity to group sequential elements of communication signals. Males of this species produce a pulsed advertisement call, to which females exhibit robust approach behavior (phonotaxis). We manipulated the spectral proximity of pulses within an advertisement call by raising or lowering the frequency of some pulses from the baseline carrier frequency. Females were given a choice between this manipulated call and a shorter call with no spectral incoherence. When presented with two calls, females generally discriminate strongly against the shorter of the two, and against calls that are missing pulses. We expected if females were able to use spectral proximity to group pulses, at small ΔF they should perceive the longer signal as a coherent, attractive call, and prefer it to the shorter call. Conversely, when ΔF was large, pulses of the long call were less likely to be grouped, making short calls more attractive. Natural calls have a bimodal frequency spectrum, with peaks at 1.3 kHz and 2.6 kHz. Each of these frequencies is primarily encoded by a distinct sensory organ (papilla) in the frog’s inner ear. We tested females with calls that had only one of the natural frequencies as its carrier frequency. This design ensured that most stimuli were primarily encoded by one of the sensory papillae, but at high stimulus amplitudes, dual stimulation of the papillae was likely. To further elucidate the roles of the sensory papillae, we performed replicates of the experiment at levels of 85 dB, 73 dB, and 61 dB. The lower levels reduced the likelihood of dual activation and better isolate the roles of the individual papillae. Female responses indicated that they are able to group acoustic signals using frequency cues, but that the mechanism responsible seems to differ between the sensory papilla. Responses to low frequency stimuli suggested that females were grouping based on frequency proximity, as humans do, while responses to high frequency stimuli were indicative of a mechanism based on perceived level differences. Our results suggest that frogs, like humans, use frequency cues for auditory grouping, but that their use of frequency cues may be supported by two different neural mechanisms, one similar to that of humans, and one that differs. [Supported by NIDCD 5R01DC009582.] Keywords: auditory grouping, Hyla chrysoscelis, sound source segregation Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster Presentation (see alternatives below as well) Topic: Sensory: Audition Citation: Schrode K and Bee MA (2012). Mechanisms of Auditory Grouping in Cope’s Gray Treefrog. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00183 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Ms. Katrina Schrode, University of Minnesota, Graduate Program in Neuroscience, St. Paul, United States, schro641@umn.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. 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