An Investigation of Learning during Propofol Sedation and Anesthesia Using the Process Dissociation Procedure

Abstract

There was no unprompted recall of surgery, but the process dissociation procedure showed memory for words presented during surgery. This memory was apparently explicit but did not correlate with the measures of depth of anesthesia used.

Is priming during anesthesia unconscious?

“…Also note that stimuli in this study were presented before surgery, whereas typical studies present them during surgery. We have hypothesized that the surgical stress response facilitates implicit priming during anesthesia (Deeprose et al, 2004;Stapleton & Andrade, 2000). If we are correct, then this study is not a strong test of the hypothesis that priming can occur when surgical patients are unconscious.…”

“…Studies by Mü nte and colleagues suggest continued auditory processing during deep anesthesia, shown by the presence of mismatch negativity in the EEG response to ÔoddballÕ auditory stimuli Quandt et al, 2004). If at least a small amount of auditory processing persists when people are anesthetized, then memory formation for this information may be facilitated by the high levels of catecholamines released in response to surgery and known to act via the amygdala to facilitate memory formation for emotional stimuli (Deeprose, Andrade, Varma, & Edwards, 2004;Stapleton & Andrade, 2000).…”

Human mediotemporal EEG characteristics during propofol anesthesia

“…As initially described, evidence for response-controlrelated declarative memory, but not for unprompted recall or recognition of items presented during deep propofol anesthesia, has been reported (Kerssens et al 2002;Stapleton et al 2000). Our own prior data indicate that declarative memory formation is accompanied by increased event-related synchronization of gamma activity between the rhinal cortex and hippocampus (Fell et al 2001).…”

“…Therefore, the difference between target responses in the inclusion and exclusion condition is a measure for the occurrence of some kind of declarative memory formation. It was found that, although none of the patients remembered or recognized the words presented during anesthesia, the difference between target responses in the inclusion and exclusion condition was significantly larger than zero (Kerssens et al 2002;Stapleton et al 2000). These results indicate the persistence of declarative memory formation during deep anesthesia.…”

“…: +49-228-2879347, Fax: +49-228-2876294) ing deep sedation found evidence for nondeclarative (implicit), but no evidence for declarative (explicit) memory, i.e., for subsequent conscious recollection of events and facts (e.g., Bethune et al 1992;Cork et al 1996;Deeprose et al 2004;Munte 1999). However, in studies implementing the so-called process dissociation procedure (Jacoby 1991), evidence for some kind of declarative memory formation during deep anesthesia was reported (Kerssens et al 2002;Stapleton et al 2000). In those investigations words were acoustically presented to patients under a near-adequate or adequate level of propofol sedation.…”