Estimating the Distribution of Synaptic Reliabilities.
Emily P. Huang and Charles F. Stevens.
Neuroscience Department, University of California, San Diego, La Jolla, CA
92093, Howard Hughes Medical Institute, The Salk Institute, La Jolla, CA 92037
APStracts 4:194N, 1997.
ABSTRACT
Using whole-cell recording from CA1 hippocampal pyramidal neurons in slices,
we examined the progressive decrease of NMDA-receptor mediated synaptic
responses in the presence of the open-channel blocker MK-801. Previous studies
analyzing this decrease have proposed that hippocampal synapses fall into two
distinct classes of release probabilities, whereas studies based on other
methods (Murthy et al. 1996; Allen and Stevens 1994) indicate a broad
distribution of synaptic reliabilities exists. Here we derive the theoretical
relationship between the MK-801 mediated decrease in epsc amplitudes and the
underlying distribution of synaptic reliabilities. We find that the MK-801
data are consistent with a continuous distribution of synaptic reliabilities,
in agreement with studies examining individual synapses. In addition, changes
in the MK-801 mediated decrease in response size as a consequence of altering
release probability are consistent with this continuous distribution of
synaptic reliabilities.
Received 24 March 1997; accepted in final form 13 August 1997.
APS Manuscript Number J249-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997