We plan to continue our studies of structural and functional properties of neurons and their significance for the processing of sensory information. The electrosensory system of gymnotiform fish serves as a model system for this research. We will explore relationships between the structure and function of neurons by intracellular labelling of physiologically identified cells. Using small, local iontophoretic applications of transmitters or their respective antagonists and by simultaneous extracellular recording from single neurons, we intend to study network properties that are due to the actions of specific transmitters. We will focus on three central nervous structures, the prepacemaker nucleus (PPN) of the midbrain, the pacemaker nucleus (PN) of the medulla, and the electrosensory lateral line lobe (ELL) of the hindbrain. The PPN contains two functionally different premotor systems to control the discharge frequency of the PN, one for inducing smooth changes in frequency, and one for eliciting abrupt, transient accelerations, or 'chirps'. Both forms of frequency modulations occur in response to electric signals of neighbors. Chirps, however, are exclusively produced by animals high in the rank order. Their occurrence in males is facilitated by testosterone and inhibited by serotonin. Serotonin inhibitors, such as methysergide, therefore, promote chirping. By small, local applications of agonists and antagonists to the PPN and its afferent structures, and by simultaneous recording from single neurons related to chirping, we want to identify the underlying structures as well as the mechanisms of neurotransmission in this system. The ELL is the first processing station for electrosensory information. It contains neurons with receptive fields on the body surface. The spatial and temporal dynamics of these fields are modulated by descending recurrent input. The mechanism of this modulation can be studied at the single-cell level by local application of transmitters and their antagonists.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
2R37MH026149-13
Application #
3486400
Study Section
Neurosciences Research Review Committee (BPN)
Project Start
1978-05-01
Project End
1993-03-31
Budget Start
1988-04-01
Budget End
1989-03-31
Support Year
13
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
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
Vischer, H A (1995) Electroreceptor development in the electric fish Eigenmannia: a histological and ultrastructural study. J Comp Neurol 360:81-100
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
Spiro, J E; Brose, N; Heinemann, S F et al. (1994) Immunolocalization of NMDA receptors in the central nervous system of weakly electric fish: functional implications for the modulation of a neuronal oscillator. J Neurosci 14:6289-99
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

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