The research I am conducting focuses on fundamental questions in hearing, and the neural mechanisms employed by the brain in the processing of communication sounds. In the natural world, the auditory system extracts critical signals, such as speech, from complex acoustic environments. This is accomplished through both mechanical and neurobiological filtering and processing. Some of this is accomplished within the ear and auditory nerve. However, a great deal is also accomplished through complex processing by the brain, and relatively little is known about this. A robust understanding of auditory processing in the brain is of clear significance to a wide range of health issues, including the development of effective therapeutic measures for the hearing impaired. I will use neurophysiological and anatomical methods to address questions about the processing of communication sounds in the brain. I will focus on the mechanisms by which temporal patterns in sounds are analyzed. Temporal patterns allow humans to localize and identify sound sources, and to process speech. It is thus not surprising that recent research has shown that the preservation of time-cues is critical in the engineering of effective cochlear implants. The applicant will use an animal model to carry out the research. The fish Pollimyrus (Mormyridae) is particularly appropriate because it uses simple temporally patterned sounds for communication, and has an auditory system that is dedicated to encoding time cues. This is a vertebrate species that can be relatively easily analyzed at both neurophysiological and anatomical levels. Recent experiments have shown that there are neurons in the brain whose activity depends upon specific temporal cues. Single cell neurophysiological recording techniques will be used to study these neurons, and to discover how their temporal selectivity originates. This will be done by recording in the brain (mesencephalon), while presenting a variety of acoustic stimuli, and while treating the neurons with neuroactive chemicals. Also to be examined are auditory responses in neurons that constitute an earlier stage of processing in the brain, to determine what the temporally selective cells receive as input.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC001252-07
Application #
6030170
Study Section
Hearing Research Study Section (HAR)
Project Start
1992-06-01
Project End
2001-06-30
Budget Start
1999-07-01
Budget End
2000-06-30
Support Year
7
Fiscal Year
1999
Total Cost
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
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
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
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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