BACKGROUND: Unconscious processing of words during general anesthesia has been suggested after surgery with several tests of implicit memory. @entity1 can neither recall those words nor do they have explicit memories of other intraoperative events. It is unclear to what degree information is processed during general anesthesia and which tests are best suited to detect implicit memory. In the current study, a lexical decision paradigm not previously used to demonstrate implicit memory during anesthesia was used. METHODS: Sixty @entity1 undergoing lumbar disc surgery were assigned to receive @entity5161 infusion- or @entity1875 infusion-based anesthesia combined with @entity680 infusions and a @entity3810 - @entity26 mixture. A control group of 10 medical students listened to tapes without receiving anesthesia. Two tapes, each containing a list of 30 low-frequency German nouns repeated for 15 min, were prepared, with half of the @entity1 listening to tape A and the other half listening to tape B during the operation. Exposure time was 15 min from the time of skin incision onward. In the test phase, approximately 7 h later, words from lists A and B plus 60 nonwords were presented in random order by a computer program. Subjects were asked to indicate, by pressing one of two response buttons, whether the spoken word was or was not a legal German word (lexical decision). RESULTS: A recognition test revealed chance recognition for words presented during anesthesia. Lexical decision responses, however, were slightly faster to primed (previously presented) words than to unprimed (not previously presented) words when the entire group of @entity1 was tested, suggesting a small implicit memory effect, which barely failed to reach the significance level. When the two medication groups were tested separately, no significant implicit memory effect could be ascertained statistically. The effects of previous exposure were much more pronounced in the control group. CONCLUSIONS: Balanced anesthesia techniques with @entity5161 or @entity1875 lead to only a minimal, statistically borderline implicit memory effect in the lexical decision paradigm.

Implicit memory for words played during XXXX - or @entity1875 -based anesthesia: the lexical decision task.

@entity1 :: ('9606', 'Species') :: ['Patients', 'patients'] @entity680 :: ('MESH:D015760', 'Chemical') :: ['alfentanil'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity1875 :: ('MESH:D015742', 'Chemical') :: ['propofol'] @entity3810 :: ('MESH:D009609', 'Chemical') :: ['nitrous oxide'] @entity5161 :: ('MESH:D007530', 'Chemical') :: ['isoflurane']
@entity5161 :: (MESH:D007530,Chemical) :: ['isoflurane']
