|Title:||Dissociation of Stimulus-lnduced Responses in Regional Cerebral Blood Flow and Blood Volume in the Visual Cortex of Humans|
|Keywords:||Near-infrared optical imaging|
Functional magnetic resonance imaging
Blood oxygenation-level dependent signal
|Journal title:||京都大学医学部保健学科紀要: 健康科学|
|Abstract:||To elucidate hemodynamic response in the human visual cortex during visual stimulation, changes in regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV) were investigated using blood oxygenation-level dependent (BOLD) and flow sensitive alternating inversion recovery (FAIR) functional magnetic resonance imaging (BOLD- and FAIR-fMRI) and I6-channel near-infrared optical imaging (NIOI) techniques. A white and black annular checherboard (visual angle: 1.2 to 5.8 degrees) focused on perimacular annulus stimulation of the retina, whose temporal frequencies were 0.5, 1.4, 4.7 and 14 Hz with a central fixation point and gray background, was used as the visual stimulus for perimacular annulus. The stimulus-induced activation area obtained with NIOI corresponded to the one measured with BOLD-fMRI. Nevertheless, a dissociation of stimulus induced responses between the BOLD-fMRI signal and hemoglobin (Hb) parameters obtained with NIOI was found; i.e., changes in BOLD-fMRI signal showed a maximal increase at a temporal frequency of l.4-4.7 Hz, while increases in oxygenated (oxy-Hb) and total hemoglobin (total-Hb) concentrations showed a minimum around the same frequency, and deoxygenated hemoglobin (deoxy-Hb) showed a slight but significant decrease. This dissociation of stimulus-induced responses of the BOLD-fMRI signal and Hb parameters could be simulated as a functions of concentration changes in oxy-Hb, deoxy-Hb, and total-Hb. The temporal frequency dependence of changes in rCBF, estimated from FAIR signal and from the time-course change in total-Hb, was similar to that of the BOLD-fMRI signal change. The present results indicated that stimulus-induced responses of rCBF were dissociated from those of rCBV in the visual cortex of humans during perimacular stimulation at temporal frequency around 1.4-4.7 Hz.|
|Appears in Collections:||第4号|
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