Modality specific type 2 theta production in the immobile rat.

The purpose of the present study was to compare the relative effectiveness of stimulation of different sensory modalities in eliciting Type 2 theta in the rat in the presence or absence of a ferret. Visual, auditory, and tactile stimuli were presented to rats in both conditions. Tactile stimulation produced more movement than either visual or auditory stimuli when the ferret was present. In both conditions, however, more Type 2 theta was observed in response to tactile or visual stimulation than to auditory stimulation. In the arousal condition, stimulation of tactile and auditory modalities resulted in significant increases in the amount of Type 2 theta produced. Input to the visual modality produced high levels of Type 2 theta production in both low- and high-arousal conditions. It is argued that Type 2 theta is not necessarily a precursor to movement but rather sensory processing while in a high state of arousal.