Neural Mechanisms of Sound Localization

Project: Research project

Project Details

Description

The long-term goal of the Pi's research is to understand neural mechanisms of sound localization in vertebrates,
including humans. The primary goal of this proposal is to determine how the primitive auditory system offish functions
in sound localization. The Pi'sprevious studies and others have demonstrated that fish determine the axis at which a
sound wave is propagating by using arrays of spatially oriented sensory hair cells in the ear. However, it is not known
how the brain processes the peripherally coded directional information in order to extract the specific direction of the
sound. The proposed work will elucidate mechanisms underlying central auditory processing of directionalinformation.
It has been proposed that the fish ear is stimulated by a sound wave through two distinct pathways: direct particle motion
input and indirect pressure input via the swim bladder. It was hypothesized that fish (with a swim bladder) first
determine the axis on which the sound is propagating and then determine its direction by comparing the timings of
inputs carrying pressure and particle motion information within the brain. The PI will test the two steps of this
hypothesis on two functionally distinguishable teleost fishes, the sleeper goby and goldfish. Specific aims address
anatomical organization and functional processing of directional information in the medulla and midbrain: 1)Auditory
nuclei responsible for directional coding. Experiments will be carried out to reveal central projection sites of the
saccular, lagenar, and utricular nerves and medullary projection sites in the midbrain using both anterograde and
retrograde labeling methods. 2) 3D structure and cytoarchitecture of the auditory nuclei. Combined with the neuronal
tracing, boundaries of the auditory nuclei will be defined to create their three dimensional structures usingNeurolucida.
Golgi stain studies will characterize types, sizes, and orientations of the auditory neurons. 3) Brain representation of the
peripheral map of directional coding. Using whole-cell filling of Neurobiotin and confocal imaging, a 3D map of
peripheral directional coding will be reconstructed to reveal how the saccular map of directional coding is represented in
the medulla. 4) Directional response properties of auditory medullary and midbrain neurons. Single-cell recording and
filling will characterize directional response properties, locations, and morphologies of auditory medullary and midbrain
neurons to form a neural map(s) of best response axes of the neurons. 5) Differential-phase sensitive neurons. Single-cell
recording will determine if there are neurons in the medulla and/or midbrain of the goldfish that encode specific timing
differences between particle motion and pressure inputs.
StatusFinished
Effective start/end date1/1/0312/31/09

Funding

  • National Institute on Deafness and other Communication Disorders: $283,183.00
  • National Institute on Deafness and other Communication Disorders: $273,840.00
  • National Institute on Deafness and other Communication Disorders: $234,817.00
  • National Institute on Deafness and other Communication Disorders: $240,468.00
  • National Institute on Deafness and other Communication Disorders: $26,001.00
  • National Institute on Deafness and other Communication Disorders: $240,468.00

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