Stimulus-evoked resetting of the dentate theta rhythm: relation to working memory.

The relationship between memory and rhythmic neural activity in the dentate gyrus was investigated by analyzing spontaneous dentate field potentials in rats performing either a working or reference memory task. The baseline level of rhythmic theta activity was similar in both groups. Following an initial negative potential in the sensory-evoked response, a resetting of the rhythmic activity which was time-locked to the stimulus onset was observed in rats performing the working memory task, but not in rats performing the reference memory task. The results suggest that the resetting of the theta rhythm by behaviorally-relevant stimuli may have an important role in working memory.