Learning in Parkinson's disease: Eyeblink conditioning, declarative learning, and procedural learning

Objective - To assess the degree of learning ability in Parkinson's disease. Methods - Three different learning tasks: eyeblink classical conditioning with delay and trace paradigms, the California verbal learning test (CVLT), and a serial reaction time task (SRTT) were studied in patients with Parkinson's disease and normal (control) subjects. Results - In the eyeblink conditioning tasks, both patients and normal subjects showed significant learning effects without between group differences. In the CVLT, patients remembered significantly fewer words than normal subjects in both short term and long term cued recall tasks. In the SRTT, normal subjects had significantly reduced response time and error rates across blocks of repeated sequence trials, whereas patients had significantly reduced error, but not response time rates. Conclusion - Impairment of nigrostriatal pathways selectively affects performance in complex learning tasks that are competitive and require alertness such as the SRTT, but not in simple learning procedures such as eyeblink conditioning.