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Extinction of conditioned blink responses by cerebello-olivary pathway stimulation

Bengtsson, Fredrik; Jirenhed, Dan-Anders; Svensson, Pär; Hesslow, Germund

doi: 10.1097/WNR.0b013e3282e326e8

Learning of classically conditioned eyeblink responses depends on mechanisms within the cerebellum. It has been suggested that climbing fibres from the inferior olive transmit the unconditioned stimulus signal to the cerebellum. We have previously shown that the pathway from the deep cerebellar nuclei to the inferior olive inhibits olivary activity. It is known that repeated presentation of the conditioned stimulus on its own leads to extinction of the conditioned response. If the unconditioned stimulus signal is transmitted to the cerebellum via the inferior olive – climbing fibre system then stimulation of the nucleo-olivary pathway just before the unconditioned stimulus in a trained animal should lead to extinction. The results from this investigation confirm this.

Department of Experimental Medical Science, University of Lund, Lund, Sweden

Correspondence to Dr Fredrik Bengtsson, PhD, Department of Experimental Medical Science, BMC F10, University of Lund, SE-221 84 Lund, Sweden

Tel: +46 46 2220597; fax: +46 46 2224546; e-mail:

Received 16 April 2007; accepted 17 May 2007

© 2007 Lippincott Williams & Wilkins, Inc.