Activity of medullary reticular formation neurons in the unrestrained cat during waking and sleep.

Single units, recorded in the medial medullary reticular formation (RF) in unrestrained, behaving cats, discharged in conjunction with specific movements and postures. Most cells were also active during REM sleep. Discharge rates in active waking and REM sleep were positively correlated and discharge patterns in these states were similar. We conclude that activity in these cells is related to the motor activation occurring in both active waking and REM sleep. We found no cells whose discharge was related in a non-specific way to motor tone or to REM sleep atonia. We discuss mechanisms by which medullary units with specific motor relations may give rise when stimulated to the relatively non-specific motor effects previously reported.