Abstract
We have previously found that inspiration phase-locked alpha oscillation (I-α) during odor stimuli was found in the averaged potential triggered by inspiration onset in normal subjects (NS). EEG dipole tracing method (DT) of the scalp-skull-brain head model (SSB)(SSB/DT)identified the location of dipole from I-α in the entorhinal cortex (ENT), hippocampus(HI), amygdala, and centroposterior orbitofrontal gyrus (CP OFG) subserve odor threshold, and the rostomedial orbitofrontal gyrus (RM OFG) subserve odor recognition. It has been reported that impaired olfaction occurs in patients with Parkinson’s disease (PD). The present study was performed to determine whether the I-α and their dipole locations in PD are different from those observed in normal subjects. Recognition level of odor were lower than normal age matched subjects according to the T & T olfaction test (NS, 1.93 ± 0.28; PD, 3.88 ± 0.88; P<0.05). I-α consists of three positive waves (I-α1, I-α2, I-α3) in normal subjects, however, I-α2, I-α3 were less active in PD. SSB/DT identified the location of dipole in the ENT and HI of the I-α1 component, but dipoles were not estimated in the CP OFG and RM OFG. The OFC is connected with the perihinal and ENT areas and plays an important role in odor recognition memory in animals and humans. PD are capable to detect odor threshold level, but having difficulty in discrimination because of the connection between ENT and OFG may be affected by pathological changes. [Jpn J Physiol 55 Suppl:S185 (2005)]
