The relationship between type 2 theta and behavior.

Although there is extensive literature on the correlation between Type 1 theta activity in the hippocampus and behavior, little is known about the behavioral correlates of "Type 2" (immobility) theta. In the present study, guinea pigs were exposed to three high "arousal" situations. These situations produced reliable trains of "Type 2" theta. Atropine sulfate abolished "arousal" and Type 2 theta. In the second study, we determined whether the Type 2 theta response was produced by specific stimuli or by a generalized sensitization to incoming sensory stimuli created by the testing situation. In this study, a stimulus which had not previously elicited Type 2 theta was presented a second time after a presentation of a stimulus which did elicit Type 2 theta. The previously neutral stimulus now elicited Type 2 theta. These results were interpreted within an "arousal" theory framework.