The research proposed here focuses on fundamental mechanisms employed by the brain for the analysis of communication sounds. Humans, and a diversity of other species, use low frequency sounds for communication, and research into the neural mechanisms that extract information encoded by the primary afferent spike trains is fundamental to the development of therapeutic measures for the hearing impaired. The fish, Pollimyrus, is used as a model for examining the neurobiology of auditory temporal processing because the animal's ear is relatively simple and is well adapted for time coding of signals, the fish uses well characterized communication sounds, and hearing can be studied with a combination of approaches including single neuron electrophysiology, anatomy and behavior. The experiments are designed to test hypotheses about the brain mechanisms that produce neurons that are sensitive to particular temporal features of communication sounds. Neurons in the auditory nerve produce trains of spikes that are precisely entrained to the time structure of sounds, but are not feature selective. In contrast, neurons in the midbrain are feature selective and must reflect the output of neural processing networks that produce selectivity from entrained input. A series of physiological and behavioral experiments will be carried out to evaluate five specific hypotheses about the nature of these neural computations: (1) Interval-selectivity is based on the time-intervals between spikes in the afferent input; (2) The mechanism producing selectivity depends upon inhibition and inhibitory rebound; (3) GABA-ergic neurons in the lemniscal nucleus IR.N provide inhibitory input to the selective neurons; (4) The system, as assessed behaviorally, is sensitive to small differences in the periods of naturalistic sounds; (5) Behavioral discrimination depends upon temporal features (i.e. phase spectrum) of periodic stimuli.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
2R01DC001252-09A2
Application #
6547441
Study Section
Special Emphasis Panel (ZRG1-IFCN-6 (01))
Program Officer
Luethke, Lynn E
Project Start
1992-06-01
Project End
2003-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
9
Fiscal Year
2002
Total Cost
$333,438
Indirect Cost
Name
University of Pennsylvania
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Suzuki, Aae; Kozloski, James; Crawford, John D (2002) Temporal encoding for auditory computation: physiology of primary afferent neurons in sound-producing fish. J Neurosci 22:6290-301
Large, Edward W; Crawford, John D (2002) Auditory temporal computation: interval selectivity based on post-inhibitory rebound. J Comput Neurosci 13:125-42
Fletcher, L B; Crawford, J D (2001) Acoustic detection by sound-producing fishes (Mormyridae): the role of gas-filled tympanic bladders. J Exp Biol 204:175-83
Kozloski, J; Crawford, J D (2000) Transformations of an auditory temporal code in the medulla of a sound-producing fish. J Neurosci 20:2400-8
Marvit, P; Crawford, J D (2000) Auditory thresholds in a sound-producing electric fish (Pollimyrus): behavioral measurements of sensitivity to tones and click trains. J Acoust Soc Am 107:2209-14
Marvit, P; Crawford, J D (2000) Auditory discrimination in a sound-producing electric fish (Pollimyrus): tone frequency and click-rate difference detection. J Acoust Soc Am 108:1819-25
Crawford, J D; Huang, X (1999) Communication signals and sound production mechanisms of mormyrid electric fish. J Exp Biol 202:1417-26
Kozloski, J; Crawford, J D (1998) Functional neuroanatomy of auditory pathways in the sound-producing fish Pollimyrus. J Comp Neurol 401:227-52
Crawford, J D; Cook, A P; Heberlein, A S (1997) Bioacoustic behavior of African fishes (Mormyridae): potential cues for species and individual recognition in Pollimyrus. J Acoust Soc Am 102:1200-12
Crawford, J D (1997) Feature-detecting auditory neurons in the brain of a sound-producing fish. J Comp Physiol A 180:439-50

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