Near-infrared spectroscopy of the adult human olfactory cortex.
OBJECTIVE
Near-infrared spectroscopy (NIRS) is a non-invasive method for investigating activation of the human cortex. The applicability of NIRS to the olfactory cortex was investigated.


METHODS
The relative oxy- and deoxy-hemoglobin levels of the orbito-frontal cortex during olfactory stimulation in healthy subjects were measured using NIRS.


RESULTS
When perfumed strips containing the odorants beta-phenyl ethyl alcohol, iso-valeric acid and gamma-undecalactone were presented, the oxy-hemoglobin level increased but the deoxy-hemoglobin level did not change. The increase in the oxy-hemoglobin level was observed bilaterally. A placebo perfumed strip did not elicit a change in the hemoglobin level. It was also observed that the odorant intensity affected the oxy-hemoglobin level. Although the orbito-frontal cortices seemed to be activated bilaterally during olfaction, the right cortex was activated to a greater extent than the left.


CONCLUSIONS
NIRS appears to be an adequate method for investigating the human olfactory cortex.
Department of Otolaryngology, Head and Neck Surgery, Nanto General Hospital, Nishitonami, Toyama, Japan. ishimaru-t@nanto-hp.jp
Tadashi
T
Ishimaru
Tsuyoshi
T
Yata
Kumiko
K
Horikawa
Sachiko
S
Hatanaka
D000328:Adult; D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009812:Odorants; D009833:Olfactory Pathways / Q000502:physiology*; D010108:Oxyhemoglobins / Q000032:analysis; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared
D006454:Hemoglobins; D010108:Oxyhemoglobins