The Journal of Neuroscience, April 1, 2001, 21(7):2434-2441
In Vitro Eye-Blink Classical Conditioning Is NMDA
Receptor Dependent and Involves Redistribution of AMPA Receptor
Subunit GluR4
Joyce
Keifer
Neuroscience Group, Division of Basic Biomedical Sciences,
University of South Dakota School of Medicine, Vermillion, South Dakota
57010
The classically conditioned vertebrate eye-blink response is a
model in which to study neuronal mechanisms of learning and memory. A
neural correlate of this response recorded in the abducens nerve can be
conditioned entirely in vitro using an isolated
brainstem-cerebellum preparation from the turtle by pairing trigeminal
and auditory nerve stimulation. Here it is reported that conditioning
requires that the paired stimuli occur within a narrow temporal window of <100 msec and that it is blocked by the NMDA receptor antagonist D,L-2-amino-5-phosphonovaleric acid. Moreover, there
is a significant positive correlation between the levels of
conditioning and greater immunoreactivity with the glutamate receptor 4 (GluR4) AMPA receptor subunit in the abducens motor nuclei, but not
with NMDAR1 or GluR1. It is concluded that in vitro
classical conditioning of an abducens nerve eye-blink response is
generated by NMDA receptor-mediated mechanisms that may act to modify
the AMPA receptor by increasing GluR4 subunits in auditory nerve synapses.
Key words:
eye blink; conditioning; in vitro; turtle; NMDA; GluR4
Copyright © 2001 Society for Neuroscience 0270-6474/01/2172434-08$05.00/0