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.
Ishimaru
Tadashi
T
Department of Otolaryngology, Head and Neck Surgery, Nanto General Hospital, Nishitonami, Toyama, Japan. ishimaru-t@nanto-hp.jp
Yata
Tsuyoshi
T
Horikawa
Kumiko
K
Hatanaka
Sachiko
S
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