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Millisecond changes in the optical properties of the human brain during stimulation were detected in five volunteers using noninvasive frequency-domain near-infrared spectroscopy. During a motor stimulation task we found highly significant signals, which were directly related to neuronal activity and exhibited much more localized patterns than the slow(More)
We investigated the influence of the adipose tissue thickness (ATT) on near-infrared spectroscopy (NIRS) measurements of the absorption coefficient (mu a), the reduced scattering coefficient (mu s') and changes in concentrations of oxyhemoglobin ([O2Hb]) and deoxyhemoglobin ([HHb]). We used a frequency domain spectrometer and a special probe to generate(More)
Using non-invasive near infrared spectroscopy fast changes in the range of ms in the optical properties of neurons during brain activity have been described. Since the signal is small, the system to detect it has to be highly noise optimized. We used a frequency-domain tissue oximeter, whose laser diodes were modulated at 110 MHz and the amplitude (AC),(More)
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