Acute effects of nitrous oxide on visual processing: a connectome study in healthy adults.
Research square January 12, 2026 Niloufar Pouyan, Chelsea M Kaplan, Tony E Larkin et al.
Subanesthetic nitrous oxide (N2O) alters visual experience by reconfiguring large-scale brain networks rather than changing early visual processing. In a placebo-controlled fMRI study with 13 healthy adults, participants viewed a flashing checkerboard and rated visual intensity and unpleasantness. Increased unpleasantness under N2O was linked to reduced connectivity between the right anterior insula and the anterior cingulate cortex and lateral occipital cortex. Network analyses revealed reduced modularity and a collapse of hierarchical organization, with sensorimotor connectivity redistributed toward salience and associative networks. These findings suggest that altered visual experience under N2O arises from disrupted salience integration and increased cross-network communication.