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Department of Anesthesiology

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Propofol and midazolam inhibit conscious memory processes very soon after encoding: an event-related potential study of familiarity and recollection in volunteers.

TitlePropofol and midazolam inhibit conscious memory processes very soon after encoding: an event-related potential study of familiarity and recollection in volunteers.
Publication TypeJournal Article
Year of Publication2009
AuthorsVeselis RA, Pryor KO, Reinsel RA, Li Y, Mehta M, Johnson R
Date Published2009 Feb
KeywordsAdolescent, Adult, Conscious Sedation, Data Interpretation, Statistical, Dexmedetomidine, Dose-Response Relationship, Drug, Electroencephalography, Evoked Potentials, Female, Humans, Hypnotics and Sedatives, Male, Memory, Mental Recall, Midazolam, Middle Aged, Photic Stimulation, Propofol, Psychomotor Performance, Reaction Time, Thiopental, Young Adult

BACKGROUND: Intravenous drugs active via gamma-aminobutyric acid receptors to produce memory impairment during conscious sedation. Memory function was assessed using event-related potentials (ERPs) while drug was present.

METHODS: The continuous recognition task measured recognition of photographs from working (6 s) and long-term (27 s) memory while ERPs were recorded from Cz (familiarity recognition) and Pz electrodes (recollection recognition). Volunteer participants received sequential doses of one of placebo (n = 11), 0.45 and 0.9 microg/ml propofol (n = 10), 20 and 40 ng/ml midazolam (n = 12), 1.5 and 3 microg/ml thiopental (n = 11), or 0.25 and 0.4 ng/ml dexmedetomidine (n = 11). End-of-day yes/no recognition 225 min after the end of drug infusion tested memory retention of pictures encoded on the continuous recognition tasks.

RESULTS: Active drugs increased reaction times and impaired memory on the continuous recognition task equally, except for a greater effect of midazolam (P < 0.04). Forgetting from continuous recognition tasks to end of day was similar for all drugs (P = 0.40), greater than placebo (P < 0.001). Propofol and midazolam decreased the area between first presentation (new) and recognized (old, 27 s later) ERP waveforms from long-term memory for familiarity (P = 0.03) and possibly for recollection processes (P = 0.12). Propofol shifted ERP amplitudes to smaller voltages (P < 0.002). Dexmedetomidine may have impaired familiarity more than recollection processes (P = 0.10). Thiopental had no effect on ERPs.

CONCLUSION: Propofol and midazolam impaired recognition ERPs from long-term memory but not working memory. ERP measures of memory revealed different pathways to end-of-day memory loss as early as 27 s after encoding.

Alternate JournalAnesthesiology
PubMed ID19194157
PubMed Central IDPMC2735240
Grant ListUL1 RR024996 / RR / NCRR NIH HHS / United States
UL1 RR024996-01 / RR / NCRR NIH HHS / United States
UL1-RR024996 / RR / NCRR NIH HHS / United States