Conclusions
By acting on gamma oscillations in a state-dependent manner, NMDA receptors might have subunit-specific role in REM sleep-associated cognitive processes.
Results
In contrast to nonselective and NR2A-preferring antagonists, Ro25-6985 did not disrupt sleep and had no effect on gamma activity during waking and slow wave sleep. It significantly increased, however, gamma power in the frontal (but not in occipital) cortex during REM sleep (by 37% ± 10%, average in the first 4 h). The effect had a short onset; enhanced gamma activity appeared as early as in the first REM sleep episode post-injection and lasted over 8 hours. Increased gamma power induced by MK-801 (46% ± 5%) and NVP-AAM077 (100% ± 8%) during REM sleep could also be detected several hours after injection when periodic alternation of sleep-wake states returned. Conclusions: By acting on gamma oscillations in a state-dependent manner, NMDA receptors might have subunit-specific role in REM sleep-associated cognitive processes.