The Journal of Neuroscience, November 1, 1998, 18(21):9010-9019
Segregation of Behavior-Specific Synaptic Inputs to a Vertebrate
Neuronal Oscillator
Jenifer
Juranek1 and
Walter
Metzner2
1 Program in Neuroscience, Department of Psychology and
2 Department of Biology, University of California at
Riverside, Riverside, California 92521-0427
Although essential for understanding the mechanisms underlying
sensorimotor integration and motor control of behaviors, very little is
known about the degree to which different behaviors share neural
elements of the sensorimotor command chain by which they are
controlled. Here, we provide, to our knowledge, the first direct
physiological evidence that various modulatory premotor inputs to a
vertebrate central pattern generator, the pacemaker nucleus in
gymnotiform electric fish, carrying distinctly different behavioral
information, can remain segregated from their various sites of origin
in the diencephalon to the synaptic termination sites on different
target neurons in the medullary pacemaker nucleus. During
pharmacological activation of each of the premotor inputs originating
from the three prepacemaker nuclei so far identified, we determined
in vivo the changes in input resistance in the neuronal elements of the pacemaker nucleus, i.e., relay cells and pacemaker cells. We found that each input yields significantly different effects
on these cells; the inputs from the two diencephalic prepacemaker nuclei, PPnC and PPnG, which resulted in increased oscillator activity, caused significantly lower input resistances in relay and
pacemaker cells, respectively, exhibiting drastically different time
courses. The input from the sublemniscal prepacemaker nucleus, which
resulted in reduced oscillator activity, however, caused a significant
increase in input resistance only in relay cells. Considering that the
sensory pathways processing stimuli yielding these behaviors are
separated as well, this study indicates that sensorimotor control of
different behaviors can occur in strictly segregated channels from the
sensory input of the brain all through to the synaptic input level of
the final premotor command nucleus.
Key words:
premotor control; parallel pathways; input resistance; Eigenmannia; pacemaker nucleus; jamming avoidance response; communication behavior
Copyright © 1998 Society for Neuroscience 0270-6474/98/18219010-10$05.00/0
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