Median nerve stimulation combined with high gamma band activity can map the hand motor cortex during awake states, but its effectiveness declines with loss of consciousness. In five patients undergoing awake craniotomy, the sensitivity of mapping using the short-latency average envelope remained relatively stable, dropping only from 100% awake to about 82% during deeper anesthesia stages. In contrast, mapping based on average power deteriorated more sharply, from 100% awake to around 21% at the deepest stage. The long-latency average envelope also showed reduced sensitivity as consciousness declined, with a slope coefficient significantly smaller than that for short-latency responses. These results suggest that short-latency envelope-based mapping is more robust across different conscious states.
Nitrous oxide, an analgesic gas, has long been thought to have euphoric and sexual effects, but these have only recently been studied scientifically. In a small experiment with 7 men and 6 women, nitrous oxide generally reduced objective measures of sexual arousal from erotic videos. However, 7 of the 13 participants reported subjectively that the gas made them more aroused, contradicting the objective measurements. The authors suggest this discrepancy may stem from nitrous oxide's effects on the endogenous opioid system, possibly acting in opposing directions centrally and peripherally, and propose the gas as a tool for investigating sexual function.