TY - JOUR
T1 - Rapid changes of optical parameters in the human brain during a tapping task
AU - Gratton, Gabriele
AU - Fabiani, Monica
AU - Friedman, David
AU - Franceschini, Maria Angela
AU - Fantini, Sergio
AU - Corballis, Paul
AU - Gratton, Enrico
PY - 1995
Y1 - 1995
N2 - Measures of parameters of the migration of near-infrared photons through the head (attenuation, or intensity and time-of-flight, or delay) have been proposed as a way of assessing noninvasively and in a quasicontinuous fashion changes in the scattering and absorption properties of brain tissue. These, in turn, may reflect functional changes associated with behavioral tasks. To test this hypothesis, we measured changes of photon migration parameters from scalp locations proximal to the motor cortex from four human subjects, tapping at a rate of 0.8 Hz with their left or right hand, or with their left or right foot. Tapping produced both slow effects (requiring several seconds) and fast effects (tracking the tapping frequency). Slow effects were characterized by increase and delay of the light passing through the hemisphere contralateral to the tapping hand. Fast effects consisted of changes in the light delay during hand tapping. Monte Carlo simulations based on layer models of the brain indicated that fast effects are consistent with changes in deep layers of the head (presumably in the cortex), and that slow effects are consistent with either a shift of absorbing material toward deeper layers or a reduction in scattering. These results suggest that optical parameters can monitor rapid changes of brain activity, matching the contralateral organization of the motor cortex.
AB - Measures of parameters of the migration of near-infrared photons through the head (attenuation, or intensity and time-of-flight, or delay) have been proposed as a way of assessing noninvasively and in a quasicontinuous fashion changes in the scattering and absorption properties of brain tissue. These, in turn, may reflect functional changes associated with behavioral tasks. To test this hypothesis, we measured changes of photon migration parameters from scalp locations proximal to the motor cortex from four human subjects, tapping at a rate of 0.8 Hz with their left or right hand, or with their left or right foot. Tapping produced both slow effects (requiring several seconds) and fast effects (tracking the tapping frequency). Slow effects were characterized by increase and delay of the light passing through the hemisphere contralateral to the tapping hand. Fast effects consisted of changes in the light delay during hand tapping. Monte Carlo simulations based on layer models of the brain indicated that fast effects are consistent with changes in deep layers of the head (presumably in the cortex), and that slow effects are consistent with either a shift of absorbing material toward deeper layers or a reduction in scattering. These results suggest that optical parameters can monitor rapid changes of brain activity, matching the contralateral organization of the motor cortex.
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U2 - 10.1162/jocn.1995.7.4.446
DO - 10.1162/jocn.1995.7.4.446
M3 - Article
AN - SCOPUS:0028875993
SN - 0898-929X
VL - 7
SP - 446
EP - 456
JO - Journal of Cognitive Neuroscience
JF - Journal of Cognitive Neuroscience
IS - 4
ER -