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|Title:||Neural Correlates of Mating Call Selectivity in the Leopard Frog, Rana P. Pipiens|
|Author(s):||Fuzessery, Zoltan Miklos|
|Department / Program:||Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Much of anuran intraspecific communication is effected through vocalizations. Of paramount importance is the species-specific mating call, which serves as a premating species isolation mechanism. Behavioral studies indicate that individuals are able to discriminate their species mating call from those of sympatric species. This thesis examines the neural basis of this behavioral selectivity.
The northern leopard frog, Rana p. pipiens, the subject of this study, has a mating call with spectral energy peaks in the low and high ends of its audible range. The frequency selectivity of single neurons was examined at four levels of the central auditory system: the dorsal medullary and superior olivary nuclei of the medulla, the torus semicircularis of the midbrain, and the posterior auditory thalamus. The primary focus was to evaluate whether neurons at these levels of the system exhibit a selectivity for the spectral peaks of the mating call.
Neuronal response selectivity for the spectral composition of sounds was found to increase as one ascends the central auditory system. Neurons of the dorsal medullary nucleus receive input from the primary auditory fibers. Their frequency selectivity is essentially identical to that of the primary afferents, with excitatory tuning curves being unimodal and reflecting peripheral two-tone inhibition. In the superior olivary nucleus, some neurons exhibit excitatory and inhibitory tuning properties absent at the periphery, suggesting that this is the first level at which neural influences dictate frequency selectivity. While some olivary neurons have multimodal excitatory tuning curves, none require tone combinations to be excited.
The majority of neurons in the auditory midbrain and thalamus exhibit tuning properties of neural origin, and their excitatory tuning curves range from being extremely broad and extremely narrow in both the frequency and intensity domains. Of particular interest that many neurons in the rostral torus semicircularis and caudal thalamus are selectively tuned to frequencies in the low and high ends of the audible range. Some of these neurons respond only when low and high frequency tones are combined. Thus their frequency selectivity closely approximates the spectral composition of the species mating call, suggesting they play a role in the selective detection of this call. These neurons represent a striking example of a central specialization for the detection of one particular complex acoustic signal.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2015-05-14|