Fig. 6.

Rate histogram and cross-correlogram of discharge in a pair of cat reticularis pontis oralis units recorded during REM sleep (top), compared with a pair of echidna reticularis pontis oralis units recorded during sleep (bottom). Counts per second on y-axis on left. Cross-correlograms of each pair computed at 50 msec binwidth are shown atright. Unit pairs in both the cat and echidna were recorded from adjacent microwires on a single bundle of 32 μm microwires. Whereas most cat and dog units fire synchronously and are cross-correlated during REM sleep (Siegel et al., 1981), none of the echidna unit pairs was cross-correlated in sleep.