EFFECTS OF EXCITATORY AMINO-ACID ANTAGONISTS ON THE PHASIC DEPOLARIZING EVENTS THAT OCCUR IN LUMBAR MOTONEURONS DURING REM PERIODS OF ACTIVE SLEEP

The membrane potential of lumbar motoneurons is dominated during the t onic periods of active sleep by glycine-mediated inhibitory postsynapt ic potentials (IPSPs), During the phasic rapid eye movement (REM) peri ods of active sleep there are also IPSPs but, in addition, the membran e potential exhibits depolarizing shifts and action potentials that oc cur in conjunction with the phasic activation of the somatic musculatu re, The present study was designed to provide evidence that an excitat ory amino acid (EAA) neurotransmitter is responsible for these pattern s of motoneuronal activation, It was found that juxtacellular microion tophoretic applications of kynurenic acid, a non-NMDA antagonist of EA A neurotransmission, blocked the depolarizing potentials of motoneuron s that arise during the REM periods of active sleep. In contrast, the selective NMDA receptor antagonist APV did not block these depolarizat ions. The conclusion is drawn that the myoclonic twitches and jerks th at characterize the REM periods of active sleep are dependent upon the excitation of motoneurons that occurs as a result of EAAs acting at n on-NMDA receptors.