Enhanced visual memory effect for negative versus positive emotional content is potentiated at sub-anaesthetic concentrations of thiopental.

TitleEnhanced visual memory effect for negative versus positive emotional content is potentiated at sub-anaesthetic concentrations of thiopental.
Publication TypeJournal Article
Year of Publication2004
AuthorsPryor KO, Veselis RA, Reinsel RA, Feshchenko VA
JournalBr J Anaesth
Date Published2004 Sep
KeywordsAdult, Anesthetics, Intravenous, Dexmedetomidine, Dose-Response Relationship, Drug, Emotions, Female, GABA Modulators, Humans, Male, Mental Recall, Middle Aged, Pattern Recognition, Visual, Photic Stimulation, Propofol, Recognition (Psychology), Thiopental

BACKGROUND: Emotional information has the ability to alter the formation and strength of a memory ('memory modulation'). Memory modulation by negative emotion is mediated by the amygdala. It is not known how gamma aminobutyric acid (GABA)ergic drugs affect the processes involved in memory modulation. This study investigates whether memory for negative emotional stimuli is more refractory to the effects of GABAergic drugs.

METHODS: Eighty-three healthy volunteers were shown a randomized sequence of 60 visual stimuli consisting of negative, positive and neutral emotive pictures, while receiving a controlled infusion of thiopental (n=31), propofol (n=31), dexmedetomidine (n=10) or placebo (n=11). After a 5 h retention interval, when drug concentration was negligible, subjects performed a recognition task with 'old' pictures randomly mixed with 'new' pictures. Drug effect was calculated as the proportionate reduction in recognition for images of each emotional valence.

RESULTS: Forty-eight subjects were included in a within-subject logistic dose-response model analysis. In the thiopental group there was a smaller drug effect seen for negative vs positive images (proportional memory reduction from baseline 0.27 (SD 0.20) vs 0.56 (0.25), P<0.001, n=20 included in analysis). A similar trend was seen in the propofol group (0.25 (0.28) vs 0.54 (0.30), n=10), but this did not attain statistical significance. No trend was seen in the dexmedetomidine group (0.33 (0.26) vs 0.24 (0.22), n=7).

CONCLUSIONS: Over a specific dose range of thiopental (target serum concentration 2-7 micro g ml(-1)), impairment of explicit memory for images with negative emotional valence is less than that for images with positive emotional valence. There is a strong possibility that propofol (target serum concentration 0.3-2.4 micro g ml(-1)) causes a similar effect. Modulation of visual memory by negative emotional content continues at sub-anaesthetic concentrations of GABAergic drugs associated with explicit memory impairment.

Alternate JournalBr J Anaesth
PubMed ID15220170
Grant ListR01 GM 58782 / GM / NIGMS NIH HHS / United States