Clinical Trial: Effect of Affective Content on Drug Induced Amnesia of Episodic Memory

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Effect of Affective Content on Drug Induced Amnesia of Episodic Memory

Brief Summary: The purpose of this research is to understand how some of the drugs commonly used in anesthesia impair memory. We are particularly interested in whether the emotion associated with a memory influences how well these drugs are able to block memory. We are studying four commonly used drugs—propofol, thiopental, midazolam, and dexmedetomidine, all of which may have slightly differing effects. We will also study an inactive substance, called a placebo, that should have no effect. The results of this study will provide information that will be useful in understanding how memory works, how these drugs affect memory, and possibly why some people don't have their memory blocked as easily as others.

Detailed Summary:

The protocol "Effect of Affective Content on Drug Induced Amnesia of Episodic Memory" investigates the relationship between the ability of affective ('emotional') content to modulate the formation of episodic memory, and the memory impairment ('amnestic') effects of several common intravenous anesthetic drugs. Because memory modulation by affective content appears to be a distinct memory process, the underlying question is whether drugs that impair memory via different mechanisms will have differing effects on memory modulation. Specifically, the objectives are: (1) To study the influence of three GABAergic agents (thiopental, propofol, and midazolam) and one α2-adrenergic agent (dexmedetomidine) on the ability of affective content to modulate the strength of episodic memory; and (2) To study whether the subliminal ('consciously imperceptible') presentation of emotional words can influence memory for visual stimuli shown immediately after the subliminal presentation.

A maximum of eighty volunteers will receive sub-anesthetic doses of one of the four study drugs, or placebo, while performing a visual continuous recognition task ('CRT') of pictures with randomly varying affective load. Drug effect on affective modulation of working and early long-term memory behavior will be examined by analyzing which images are and are not recognized during the CRT. Drug effect on affective modulation of later long-term memory will be examined by analyzing which images are recognized several hours after presentation.

In a second experiment, emotive and non-emotive words are subliminally presented immediately before the presentation of a 'bland' picture. The ability of the subliminally presented word to influence memory will be examined by analyzing which bland images are recognized several hours later.