Delay classical eyeblink conditioning is an important model of associative, cerebellar dependent learning. Our laboratory has been investigating the role of norepinephrine (NE) in this learning paradigm. We have demonstrated that blocking either the β-noradrenergic receptor (SFN 2003), adenylate cyclase or protein kinase A (SFN 2002) with local infusions into cerebellar lobule HVI and interpositus nucleus can interfere with learning. In this study our goal was to determine whether NE release is observed in HVI during delay eyeblink conditioning. Rats were prepared for in vivo microdialysis in order to monitor the NE levels prior to and during training trials. Three month old F344 rats were operated to place microdialysis probe guide cannulas into cerebellar lobule HVI and to anchor headstages with EMG eyelid monitoring wires to the skull. The night before training microdialysis probes were placed into cerebellar lobule HVI at a flow rate 0.1 ml/min. The following morning rats were placed into the eyeblink ...