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The cerebellum and eyeblink conditioning

Hardiman, Mervyn James; (1996) The cerebellum and eyeblink conditioning. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Lesions of lobule HVI of the cerebellar cortex or of its target in the anterior cerebellar nuclei disrupt the acquisition and retention of conditioned nictitating membrane responses (CRs). The critical locus for the acquisition and retention of CRs remains controversial. Some have argued that the primary site of learning and memory is in the cerebellar nuclei. Others have maintained that the apparent abolition of CRs merely reflects a weakening of all responses or a shift in their timing caused by a motor deficit. Aspiration lesions of the cerebellar cortex cause retrograde degeneration of precerebellar nuclei. Since the loss of CRs from lesions of the cerebellar cortex might be due to the loss of collateral inputs to the cerebellar nuclei from the precerebellar nuclei, fibre sparing lesions were made which destroyed only cells in the cerebellar cortex. CRs were lost, demonstrating that the cerebellar cortex is required for retention of CRs and that the cerebellar nuclei on their own cannot maintain CRs. Fibre sparing lesions of the anterior cerebellar nuclei prevented the acquisition and abolished retention of CRs. There were no late CRs. Reflex responses remained essentially intact demonstrating that the absence of CRs was not simply due to a motor impairment. If the cerebellum is involved in conditioning it is likely that an auditory CS would be relayed to the cerebellum from the basilar pontine nuclei (PN). WGA-HRP injections into the inferior colliculus revealed a projection to caudal regions of PN, thus demonstrating a pathway whereby a tone CS can be transmitted to the cerebellum. Lesions which include the ansiform lobe as well as HVI disrupt CRs more completely than HVI lesions alone. WGA-HRP injections into ansiform lobule revealed connections from the PN and inferior olive appropriate for transmitting CS and US related information. These connections to ansiform lobule were sparse, consistent with the fact that this region is not the primary locus for NMR conditioning.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The cerebellum and eyeblink conditioning
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Biological sciences; Conditioned responses
URI: https://discovery.ucl.ac.uk/id/eprint/10103440
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