Effects of measurement method, wavelength, and source-detector distance on the fast optical signal
Effects of measurement method, wavelength, and source-detector distance on the fast optical signal
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DOI：
10.1016/j.neuroimage.2006.05.030
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发表时间：
2006-10-01
期刊：
影响因子：
5.7
通讯作者：
Fabiani, Monica
中科院分区：
文献类型：
--
作者：
Gratton, Gabriele;Brumback, Carrie R.;Fabiani, Monica
快速光信号可以用来研究局部皮质区神经元活动的时间过程。这类信号的首次报道[Grafton， G., Corballis， P. M., Cho， E., Fabiani， M., Hood， D., 1995]。灰质的阴影：在视觉刺激过程中人类大脑反应的非侵入性光学图像。心理医学杂志，32,505-509。]是基于光子延迟测量。随后，其他实验室也测量了快速光信号，但关于这些信号是如何产生和最佳记录的争论仍然存在。在这里，我们报告了来自视觉刺激范式的数据，其中使用不同参数（连续：直流强度；调制：交流强度和光子延迟）、波长（比血红蛋白等吸收点短和长）和源-探测器距离（短和长于22.5 mm）来记录快速信号。结果表明，延迟和交流强度测量均能在视觉皮层检测到局部快速信号（峰值延迟= 80 ms），但未调制的直流测量无法检测到。这可能是由于差分测量（延迟和交流强度）对严重影响直流强度的表面噪声源不太敏感。快速效应在比血红蛋白等吸点更短和更长的波长上有相似的标志，与光散射一致，但与这种现象的快速脱氧不一致。最后，快速信号仅在源-检测器距离大于22.5 mm处测量，这与信号的颅内起源一致，并提供了记录的最小距离指示。这些数据解决了该领域的一些悬而未决的问题，并为快速光信号的最佳记录方法提供了指示。(c) 2006爱思唯尔公司版权所有。
Fast optical signals can be used to study the time course of neuronal activity in localized cortical areas. The first report of such signals [Grafton, G., Corballis, P. M., Cho, E., Fabiani, M., Hood, D., 1995a. Shades of gray matter: Noninvasive optical images of human brain responses during visual stimulation. Psychophysiol, 32, 505-509.] was based on photon delay measures. Subsequently, other laboratories have also measured fast optical signals, but a debate still exists about how these signals are generated and optimally recorded. Here we report data from a visual stimulation paradigm in which different parameters (continuous: DC intensity; modulated: AC intensity and photon delay), wavelengths (shorter and longer than the hemoglobin isosbestic point), and source-detector distances (shorter and longer than 22.5 mm) were used to record fast signals. Results indicate that a localized fast signal (peak latency = 80 ms) can be detected with both delay and AC intensity measures in visual cortex, but not with unmodulated DC measures. This is likely due to the fact that differential measures (delay and AC intensity) are less sensitive to superficial noise sources, which heavily influence DC intensity. The fast effect had similar sign at wavelengths shorter and longer than the hemoglobin isosbestic point, consistent with light scattering but not rapid deoxygenation accounts of this phenomenon. Finally, the fast signal was only measured at source-detector distances greater than 22.5 mm, consistent with the intracranial origin of the signal, and providing indications about the minimum distance for recording. These data address some of the open questions in the field and provide indications about the optimal recording methods for fast optical signals. (c) 2006 Elsevier Inc. All rights reserved.