The Journal of Neuroscience, 1999, 19:RC45:1-6
RAPID COMMUNICATION
Cerebellar Cortical AMPA-Kainate Receptor Blockade Prevents
Performance of Classically Conditioned Nictitating Membrane
Responses
P. J. E.
Attwell,
S.
Rahman,
M.
Ivarsson, and
C. H.
Yeo
Department of Anatomy and Developmental Biology, University College
London, London WC1E 6BT, United Kingdom
Classical conditioning of the nictitating membrane-eye blink
response of rabbits is a simple form of associative motor learning. Lesion studies have shown that performance of learned responses is
dependent on the cerebellum, but they have not shown whether there is
storage of memories within the cerebellum or distinguished the roles of
the cerebellar cortex and nuclei. Reversible inactivations of the
cerebellar nuclei have directly implicated the cerebellum in the
acquisition of nictitating membrane conditioning, but previously the
cerebellar cortex has not been reversibly inactivated to assess its
contribution to the performance or acquisition of conditioned responses. Here we use the water-soluble disodium salt of
6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reversibly to block
cerebellar cortical AMPA-kainate receptors in lobule HVI and
quantitative autoradiography to map its distribution. Conditioned
responses are completely, but reversibly, abolished for 10-60 min
depending on the concentration of the CNQX infusion and its location
within HVI. Zebrin immunohistochemistry was used to define the optimal
cortical infusion site that, we suggest, corresponds to the location of
the eye blink control regions. We confirm that areas in HVI are
essential for the expression of classically conditioned nictitating
membrane responses, and we establish a method to analyze the role of
cerebellar cortex in the acquisition of this form of motor learning.
Key words:
classical conditioning; eye blink; cerebellar cortex; AMPA receptors; reversible inactivation; motor learning
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