Nitrous oxide impairs selective stages of working memory in rats.

Working memory impairment under narcosis has never been investigated. Furthermore, mechanisms by which narcosis disturbs working memory processes remain relatively unknown. The present work was aimed at answering to these two questions using a well-known normobaric narcotic gas, nitrous oxide (N2O), and a classical working memory task (a two-trial recognition memory task). Ten Long-Evans rats were tested in this behavioral task under nitrous oxide exposure. The results showed (i) a dose-related impairment of working memory, (ii) a selective effect of N2O on two out of three mnemonic processes: acquisition, and retention, and (iii) a compensatory effect of increasing the acquisition phase duration on these impairments. These results, as previously suggested for long-term memory, agree with the fact that nitrous oxide disrupts in a dose-related manner working memory by notably slowing down acquisition processes. Copyright 2004 Elsevier Ireland Ltd.