Inspiratory phase-locked alpha oscillation in human olfaction: source generators estimated by a dipole tracing method

• Published in: The Journal of physiology Vol. 566; no. 3; pp. 979 - 997
• Main Authors: Masaoka, Yuri, Koiwa, Nobuyoshi, Homma, Ikuo
• Format: Journal Article
• Language: English
• Published: 9600 Garsington Road , Oxford , OX4 2DQ , UK The Physiological Society 01.08.2005; Blackwell Science Ltd; Blackwell Science Inc
• Subjects: Action Potentials - physiology; Adult; Biological Clocks - physiology; Brain Mapping - methods; Evoked Potentials - physiology; Humans; Inhalation - physiology; Integrative Physiology; Male; Neurons, Afferent - physiology; Olfactory Pathways - physiology; Smell - physiology
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.2005.086124

Olfactory perception and related emotions are largely dependent on inspiration. We acquired simultaneous respiration and electroencephalographic recordings during pleasant odour and unpleasant odour stimulation. We sought to identify changes in respiratory pattern, inspiratory-related potentials and location of dipoles estimated from the potentials. Electroencephalographic recording was triggered by inspiration onset. Respiratory frequency decreased at pleasant odour recognition, and it increased at unpleasant odour detection and recognition. O 2 consumption records showed that these changes were not due to metabolic demand. During olfactory stimulation, inspiratory phase-locked alpha oscillation (I-α) was found in the averaged potential triggered by inspiration onset. I-α was observed at both pleasant odour and unpleasant odour detection and recognition, but it was not seen in the inspiration-triggered potentials of normal air breathing. Electroencephalographic dipole tracing identified the location of dipoles from the I-α in the limbic area and the cortex; the entorhinal cortex, hippocampus, amygdala, premotor area and centroposterior orbitofrontal cortex subserve odour detection, and the rostromedial orbitofrontal cortex subserves odour recognition. We suggest that the I-α in our study originated from the olfactory cortex in the forebrain and was phase-locked to inspiration.