THE RHYTHMIC SLOW ACTIVITY RECORDED FROM ENTORHINAL CORTEX IN FREELY MOVING CATS

The relationships between the entorhinal cortex (EC) and the hippocamp al formation (Hipp) field potentials were examined in the present stud y. The detailed analyses of the signal let us group the patterns of th eta appearance into three categories: (1) Theta rhythm dominating in b oth recordings from the EC and from the Hipp (2) Theta rhythm dominati ng in the Hipp with irregular activity in the EC (3) Theta rhythm domi nating in the EC with irregular activity in the Hipp. These findings p rovide the evidence for the intrinsic generator of theta rhythm to be localized in entorhinal cortex in cats.