Unconscious auditory priming during surgery with propofol and nitrous oxide anaesthesia: a replication

Abstract

Existing knowledge can be primed by information presented during propofol and nitrous oxide anaesthesia. This priming is evidence of unconscious information processing and not the result of moments of awareness.

Is priming during anesthesia unconscious?

“…Hormonal stress responses may increase the chance of priming during surgery compared with before surgery, but two studies using BIS to control anesthetic depth during surgery found no evidence of priming using the Robinson Crusoe story (Struys et al, 1998) and a category generation task . However, with a word stem completion test, we demonstrated priming during surgery with an anesthetic that was relatively deep on average (Deeprose et al, 2004) and replicated that finding in patients for whom anesthetic depth remained below a BIS value of 60 throughout word presentation (Deeprose et al, 2005). The difference between our results and those of and Struys et al (1998) may reflect our use of a perceptual rather than conceptual priming task.…”

“…In a second study, we replicated the finding of priming during surgery using the same stimuli and tests as before, and provided stronger evidence that priming occurs in the absence of awareness (Deeprose, Andrade, Harrison, & Edwards, 2005). Each stimulus word was presented 15 times and BIS was recorded at the start and end of each series of repetitions.…”

“…In contrast, some studies using EEG measures suggest that priming does take place in the absence of awareness. Although we see that priming is related to depth, most clearly in Lubke et alÕs (1999) study of trauma patients, it also takes place when anesthesia is within clinically adequate ranges (Deeprose et al, 2004(Deeprose et al, , 2005Gidron et al, 2002;Iselin-Chaves et al, in press;Lubke et al, 1999; but see Kerssens et al, , 2005Struys et al, 1998).…”

“…Iselin-Chaves et al replicated our finding of priming with a different anesthetic, whereas Kerssens et al found no priming. Kerssens et al used BIS monitoring to maintain anesthetic depth between BIS 40 and 60, whereas we used it retrospectively to show priming in patients whose BIS values happened to stay below 60 (Deeprose et al, 2005). Although the data are somewhat equivocal, the weight of the evidence from the BIS studies suggests that perceptual priming occurs during adequate anesthesia.…”

Learning and Memory During Sleep and Anesthesia

“…83,84,86 Evidence suggests that implicit memory priming can be facilitated by surgical stimulation under anesthesia. 87,88 In part, this seems plausible because cortisol is released into circulating blood as a response to surgical stress, which then activates the amygdala. 89 Involvement by this part of the limbic system is responsible for emotional memory.…”