In vitro eye-blink classical conditioning is NMDA receptor dependent and involves redistribution of AMPA receptor subunit GluR4.
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.
Neuroscience Group, Division of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57010, USA. jkeifer@usd.edu
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D000010:Abducens Nerve; D000818:Animals; D001767:Blinking / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D066298:In Vitro Techniques; D007858:Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D018091:Receptors, AMPA / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate; D013569:Synapses / Q000502:physiology; D014426:Turtles / Q000502:physiology*
D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; C104724:glutamate receptor ionotropic, AMPA 4