Use of nitrous oxide to dissociate the non-specific and specific components of the human auditory N1

The components of the N₁ are thought to be related to sensory functioning (Components 1 and 2) and arousal (Component 3). To provide direct evidence for the involvement of Component 3 in arousal, we hypothesized that it should be more sensitive to the anesthetic gas nitrous oxide (N₂O) than Component 1. Using the technique of selective adaptation, 30 blocks of 5 tones were presented at 1 min intervals to 9 subjects who breathed air, 25% and 35% N₂O. As hypothesized, the amplitude of Component 3 was significantly reduced in a dose-dependent manner by N₂O, but the amplitude of Component 1 was not, although the latter showed some evidence of a decrease at 25% N₂O.