Farzan Nadim farzan at
Fri Mar 31 00:59:10 EST 1995

Available Immediately
Postdoctoral Fellowship
Emory University
Department of Biology
Atlanta, GA 30322
Salary - Negotiable depending on experience, two years guaranteed,
renewable for a third year.
        Our lab takes a dual physiological and computational approach
toward understanding restricted neural networks that control rhythmic
movements. The laboratory has expertise in computational techniques
using a UNIX environment and biophysical techniques with intracellular
sharp electrodes. Ideally the successful applicant would have
expertise in at least one of these areas and would be trained in the
complementary techniques. He or she would then combine these two
approaches in attacking experimental problems. The following is the
abstract from the NIH Grant which would support the fellow
(1R01-NS54149, Ronald L. Calabrese, P.I.).
        We have analyzed in detail the neuronal network that generates
heartbeat in the leech. Reciprocally inhibitory pairs of heart
interneurons form oscillators that pace the heartbeat rhythm. Other
heart interneurons coordinate these oscillators; these coordinating
interneurons with the oscillator interneurons form an 8 cell timing
oscillator network for heartbeat. Still other interneurons, along with
the oscillator interneurons, inhibit heart motor neurons, sculpting
their activity into rhythmic bursts. Critical switch interneurons
interface between the oscillator interneurons and the other premotor
interneurons to produce two alternating coordination states of the
motor neurons. The period of the rhythm generating interneurons are
modulated by endogenous RFamide neuropeptides.
        We have explored the ionic currents, and graded and
spike-mediated synaptic transmission that promote oscillation in the
oscillator interneurons and have incorporated these data into a
conductance based computer model. This model has been of considerable
predictive value and has led to new insights into how reciprocally
inhibitory neurons produce oscillation. We are now in a strong
position to expand this model upward, to encompass the entire
heartbeat network, horizontally, to elucidate the mechanisms of
FMRFamide modualtion, and downward, to incorporate cellular
morphology. These modeling studies in conjunction with parallel
physiological experiments, either proposed herein or already ongoing
in the lab, will contribute to our understanding of how rhythmic motor
acts are generated, coordinated intersegmentally, modulated and
reconfigured at the network, cellular, ionic current, and synaptic
        By studying the processes for motor pattern formation in the
leech we will uncover important insights into the function of more
complex motor systems. The computational approach that we propose will
also generate insights into the function of distributed neural
networks in general.
Ronald L. Calabrese
rcalabre at
World Wide Web:

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