Behavior dependent activities of a central pattern generator in freely
behaving Lymnaea stagnalis.
Rene F. Jansen, Anton W. Pieneman and Andries ter Maat.
Graduate School Neurosciences Amsterdam, Research Institute Neurosciences
Vrije Universiteit, Faculty of Biology, De Boelelaan 1087, 1081 HV Amsterdam,
The Netherlands, Tel: +31-20-4447094, Fax:+31-20-4447123, email:
renej@bio.vu.nl.
APStracts 4:204N, 1997.
ABSTRACT
Cyclic or repeated movements are thought to be driven by networks of neurons
(central pattern generators) that are dynamic in their connectivity. We
investigated during two unrelated behaviors (feeding and egg laying) the
behavioral output of the buccal pattern generator as well as the electrical
activity of a pair of identified interneurons that have been shown to be
involved in setting the level of activity of this pattern generator (PG).
Analysis of the quantile plots of the parameters that describe the behavior
(movements of the buccal mass) reveals that during egg laying the behavioral
output of the PG is different compared to that during feeding. Comparison of
the average durations of the different parts of the buccal movements showed
that that during egg laying the duration of one specific part of buccal
movement is increased. Correlated with these changes in the behavioral output
of the PG were changes in the firing rate of the cerebral giant neurons (CGC),
a pair of interneurons that have been shown to modulate the activity of the
pattern generator by means of multiple synaptic contacts with neurons in the
buccal ganglion. Interval- and autocorrelation histograms of the behavioral
output and CGC spiking show that both the PG output and the spiking properties
of the CGCs are different when comparing egg laying animals to feeding
animals. Analysis of the timing relations between the CGCs and the behavioral
output of the PG showed that both during feeding and egg laying the electrical
activity of the CGCs is largely in phase with the PG output, although small
changes occur. It is discussed how these results lead to specific predictions
about the kinds of changes that are likely to occur when the animal switches
the PG from feeding to egg laying and how the hormones that cause egg laying
are likely to be involved.
Received 15 August 1997; accepted in final form 15 August 1997.
APS Manuscript Number J935-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997