Decoupling motor memory strategies: effects of sleep deprivation and amphetamine.

The purpose of this study was to examine motor memory strategies using sleep deprivation as a probe. Eighteen healthy men participated in a three-day study in which they underwent repeated testing on a kinesthetic arm position replication task. On the morning of Day 3, after approximately 48 hr sleep deprivation, they ingested either 20 mg d-amphetamine or placebo. Results showed that throughout Day 3 performance remained relatively unimpaired at medial positions for both groups. For positions shifted 25 degrees laterally, accuracy was also relatively unimpaired for the amphetamine group but was compromised for the placebo group. It was concluded that sleep deprivation-induced decrements in positioning ability were due to disruption of kinesthetic memory, a narrowing of attention, or both. Kinesthetic feedback, and encoding and retrieval processes of the spatial reference system were preserved.