Aj. Fallgatter et al., PREFRONTAL HYPOOXYGENATION DURING LANGUAGE PROCESSING ASSESSED WITH NEAR-INFRARED SPECTROSCOPY, Neuropsychobiology, 37(4), 1998, pp. 215-218
Near-infrared spectroscopy (NIRS) is a noninvasive optical method whic
h allows in vivo measurements of relative concentrations of oxygenated
(O(2)Hb) and desoxygenated hemoglobin (HHb). It has been successfully
applied to assess the blood oxygenation changes during cerebral ische
mia in man. An interesting application of NIRS is the investigation of
regional cerebral blood oxygenation during physiological brain functi
ons. In the present study, left and right anterior prefrontal brain ar
eas of 10 healthy subjects were investigated with 2-channel NIRS durin
g language processing treading aloud). Nonverbal visual perception (pi
cture observation) was performed as a control condition. Compared to t
he respective baseline conditions, a significant HHb increase and an O
(2)Hb decrease as a trend were found during language processing but no
t during the nonverbal perceptual task, and no hemispheric differences
were found. The metabolic activation patterns differed significantly
between the tasks indicating the changes due to the language-related e
fforts but not to visual perception. Based on previous findings of met
abolic brain imaging studies the results are best explained as a compl
ementary phenomenon consisting in relative anterior prefrontal hypoper
fusion due to a blood volume redistribution which favors language-rela
ted temporal areas.