Structure of the Network Mediating Siphon-Elicited Siphon Withdrawal in
Frost, William N., and Eric R. Kandel.
Howard Hughes Medical Institute, New York, New York 10032 and Center for
Neurobiology and Behavior, Columbia University College of Physicians and
Surgeons, New York State Psychiatric Institute, Department of Neurobiology and
Anatomy, University of Texas Medical School, P.O. Box 20708, Houston, TX
APStracts 2:0008N, 1995.
SUMMARY AND CONCLUSIONS
1. The network mediating siphon-elicited siphon withdrawal in Aplysia is a
useful model system for cellular studies of simple forms of learning and
memory. Here we describe 3 new cells in this circuit, L33, L34 and L35, and
several new connections amongst the following network neurons: LE, L16, L29,
L30, L32, L33, L34, L35. Based on these findings, we present an updated
diagram of the network. Altogether, 100 neurons have now been identified in
the abdominal ganglion which can participate in both siphon-elicited and
spontaneous respiratory pumping siphon withdrawals. 2. Two features of the
interneuronal population may have important behavioral functions. First, the
L29 interneurons make fast and slow excitatory connections onto the LFS cells,
which may be important for transforming brief sensory neuron discharges into
the long lasting motor neuron firing which underlies withdrawal duration.
Second, inhibitory interneurons are prominent in the network. The specific
connectivity of certain of these interneurons is appropriate to block
potentially interfering inhibitory inputs from other networks during execution
of the behavior. 3. Deliberate searches have so far revealed very few
excitatory interneuronal inputs to the network interneurons and motor neurons
within the abdominal ganglion. These results, together with intracellular
studies by others, are more consistent at present with a relatively dedicated,
rather than a highly distributed organizational scheme for the siphon-elicited
siphon withdrawal circuitry.
Received 10 February; accepted in final form 8 February 1995.
APS Manuscript Number J68-4.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 3 April 1995.