Abstract
In urethane-chloralose anesthetized pigs, we examined theta activities in the temporal hippocampus by odor stimulation with the commonly used odor, beta-phenyl ethyl alcohol (PEA; rose-like odor). By stimulation with lower concentration of PEA (10−4w/w), power of type-1 theta (6-12 Hz) remained almost unchanged, but that of type-2 theta (4-6 Hz) was significantly increased. By stimulation with higher concentration (10−3w/w) of PEA, power of the type-1 and type-2 theta both gradually increased. The present study indicates the type-2 theta activity to the hippocampus of the pigs can separately be activated from the type-1 theta by odor stimulation with the low concentration of PEA. The type-1 theta may be activated with the type-1 in the temporal hippocampus of the pigs by stronger odor stimulation with PEA. Neural subsystems producing two theta rhythms to the hippocampus may be present which underlie olfactory cognition in the brain of the pigs. [J Physiol Sci. 2008;58 Suppl:S143]
