Dissociations within nondeclarative memory in Huntington's disease.

Abstract

Patients with Huntington's Disease (HD) were tested on 2 tasks, probabilistic classification learning and artificial grammar learning. Both tasks are performed normally by amnesic patients and are considered to be independent of declarative memory. Patients with HD were severely impaired in probabilistic learning but performed normally in artificial grammar learning. The probabilistic classification task may be akin to habit-learning tasks that depend on the neostriatum, whereas artificial grammar learning may depend on changes within neocortex similar to what is thought to occur in perceptual priming. The deficit in the probabilistic classification task indicates that impaired nondeclarative learning in patients with HD occurs not only in motor tasks but also in nondeclarative learning tasks that have no motor component. Huntington's disease (HD) is an inherited progressive neurological disorder that is characterized by involuntary, choreiform movements, affective disturbance, and progressive cognitive and functional decline. The primary neuropathology