Activation of the visual cortex imaged by 24-channel near-infrared spectroscopy.
Near-infrared spectroscopy (NIRS) is a noninvasive technique for continuous monitoring of the amounts of total hemoglobin (total-Hb), oxygenated hemoglobin, (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). The purpose of the present study was to demonstrate the utility of NIRS in functional imaging of the human visual cortex. A new NIRS imaging system enabled measurements from 24 scalp locations covering a 9 cm sq area. Topographic images were obtained from interpolations of the concentration changes between measurement points. Five healthy subjects between 25 and 49 years of age were investigated. After a resting baseline period of 50 s, the subjects were exposed to a visual stimulus for 20 s, followed by a 50 s resting period in a dimly lit, sound attenuating room. The visual stimulus was a circular, black and white, alternating checkerboard. In four of five subjects the visual cortex was the most activated area during visual stimulation. This is the first reported use of a NIRS-imaging system for assessing hemodynamic changes in the human visual cortex. The typical hemodynamic changes expected were observed; the total-Hb and oxy-Hb increased just after the start of stimulation and plateaued after 10 s of the stimulation period.
Tokyo Metropolitan Matsuzawa Hospital, Japan. kazumi-t@matsuzawa-hp.metro.tokyo.jp
K
K
Takahashi
S
S
Ogata
Y
Y
Atsumi
R
R
Yamamoto
S
S
Shiotsuka
A
A
Maki
Y
Y
Yamashita
T
T
Yamamoto
H
H
Koizumi
H
H
Hirasawa
M
M
Igawa
D000328:Adult; D002560:Cerebrovascular Circulation; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism; D010775:Photic Stimulation; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014793:Visual Cortex / Q000098:blood supply / Q000737:chemistry / Q000502:physiology*
D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin