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| + | Finally, the temporal resolution of fMRI is typically 0.5 Hz (i.e., a whole-brain sample every | ||
| + | 2 s). This slow sample rate has proven to be sufficient for most applications because the underlying | ||
| + | hemodynamic response is an order of magnitude slower. In contrast, fNIRS is typically recorded | ||
| + | at 10 Hz and higher sampling rates are possible because detection of the optical response is not | ||
| + | limited by the interaction between slice selection and gradient encoding in fMRI. Thus, fNIRS | ||
| + | has much better temporal resolution than fMRI and in principle could provide a more accurate | ||
| + | measure of the shape and timing of the hemodynamic response. In practice, however, that potential | ||
| + | has not yet been realized, in part because of noise from noncortical, | ||
| + | (which does not affect fMRI) and because infants cannot provide a sufficient number of stimulus blocks (or events) to average out the noise. Moreover, phased-array head coils have improved the | ||
| + | sampling rates of fMRI (Keil et al. 2013) so that the intrinsic superiority of fNIRS in the temporal | ||
| + | domain is not likely to be a significant advantage in the future. | ||
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