The goal is to understand how neural networks process biologically relevant sensory information and orchestrate adaptive behavioral responses. The electric sense of fish has been chosen as a model system since, in spite of its relative simplicity, it shares basic design principles with hearing and vision in higher animals. We want to continue intracellular studies of neurons in the midbrain region of weakly electric fish in order to relate physiological response properties to morphological features. Electric fish evaluate modulations in the amplitude and phase of the electric signal that results from the interference of their own electric organ discharges (EODs) with those of neighbors. Similar, but spatially varying modulations in phase and amplitude are caused by moving objects, and the detection of such objects may thus be impaired by interfering EODs. Much as in the auditory system of the owl, phase and amplitude information are coded and processed by separate neuronal channels up to the level of the midbrain. Both forms of information are then combined for the control of behavioral responses. Physiologically identified neurons are labelled by intracellular injection of either HRP or Lucifer Yellow and studied under the light microscope in order to determine their morphological features, such as laminar location of somata, dendritic organization and targets of projection. We will attempt to correlate differences in dendritic morphology with differences in functional properties, such as sensitivity to either phase or amplitude modulations, sensitivity to spatio-temporal modulations of phase and amplitude that characterize the effects of moving objects, and vulnerability of object detection to jamming. Of particular interest are: 1) Neurons of laminae 5 and 7 of the mesencephalic torus that appear to receive phase information only to the extent that their dendrites invade lamina 6, where phase information arrives from the hindbrain and where differences in the phase of signals relayed from different parts of the body surface are computed. 2) Laminar location and morphology of total neurons that detect moving objects but also are sensitive to jamming signals with particular frequency relations to the animal's own EOD.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS022244-04
Application #
3404432
Study Section
Communication Sciences and Disorders (CMS)
Project Start
1985-12-01
Project End
1992-11-30
Budget Start
1988-12-01
Budget End
1989-11-30
Support Year
4
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Earth Sciences/Resources
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Wong, C J (2000) Electrical stimulation of the preoptic area in Eigenmannia: evoked interruptions in the electric organ discharge. J Comp Physiol A 186:81-93
Wong, C J (1997) Connections of the basal forebrain of the weakly electric fish, Eigenmannia virescens. J Comp Neurol 389:49-64
Wong, C J (1997) Afferent and efferent connections of the diencephalic prepacemaker nucleus in the weakly electric fish, Eigenmannia virescens: interactions between the electromotor system and the neuroendocrine axis. J Comp Neurol 383:18-41
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Heiligenberg, W; Metzner, W; Wong, C J et al. (1996) Motor control of the jamming avoidance response of Apteronotus leptorhynchus: evolutionary changes of a behavior and its neuronal substrates. J Comp Physiol A 179:653-74
Wessel, R (1995) In vitro study of phase resetting and phase locking in a time-comparison circuit in the electric fish, Eigenmannia. Biophys J 69:1880-90
Kennedy, G; Heiligenberg, W (1994) Ultrastructural evidence of GABA-ergic inhibition and glutamatergic excitation in the pacemaker nucleus of the gymnotiform electric fish, Hypopomus. J Comp Physiol A 174:267-80
Metzner, W (1993) The jamming avoidance response in Eigenmannia is controlled by two separate motor pathways. J Neurosci 13:1862-78
Heiligenberg, W; Kawasaki, M (1992) An internal current source yields immunity of electrosensory information processing to unusually strong jamming in electric fish. J Comp Physiol A 171:309-16
Zupanc, G K; Airey, J A; Maler, L et al. (1992) Immunohistochemical localization of ryanodine binding proteins in the central nervous system of gymnotiform fish. J Comp Neurol 325:135-51

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