  This study demonstrates the capability of external signal recording into
memory and the reproduction of memory trace of this pattern in EEG by direct AC
electrical stimulation of rat cerebral cortex. Additionally, we examine shifts
of the DC potential level related to these phenomena. We show that in the
course of memory trace reproduction, consecutive phases of engram activation
and relaxation are registered and accompanied by corresponding negative and
positive DC shifts. The observed electrophysiological changes may reflect
consecutive activation and inhibition phases of neural ensembles participating
in engram formation.

Neurons and Cognition