Maclin Edward L, Low Kathy A, Sable Jeffrey J, Fabiani Monica, Gratton Gabriele
Department of Psychology and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Neuroimage. 2004 Apr;21(4):1798-804. doi: 10.1016/j.neuroimage.2003.11.019.
The event-related optical signal (EROS) uses near-infrared light to study changes in neuronal optical properties in response to stimuli and endogenous events. EROS responses to electrical stimulation of the median nerve at 1, 5, and 8 Hz were collected from 80 channels in 7 subjects. Optical recording channels were spatially aligned by co-registering the digitized fiber locations with structural magnetic resonance images (MRI) for each subject separately. The co-registered data sets were then transformed into Talairach space to permit alignment across subjects. After alignment, data from channels underlying pixels of a surface projection were combined to produce maps of Z statistics. Waveforms associated with voxels within an a priori region of interest (ROI) over the hand area of primary somatosensory (SI) cortex were compared across the three stimulus frequencies. Reliable early increases in light propagation time (i.e., increased phase delay) were found in SI as early as 16-32 ms of poststimulus for all three frequency conditions, and both an increase in phase delay and a decrease in signal intensity were observed over SI at longer latencies. A split-half analysis of the 8 Hz condition demonstrated the replicability of the response. This represents the first direct comparison of intensity and delay measures of these components of the somatosensory response; further, it shows that these early cortical components are replicable across subjects and correspond well to individual subjects' anatomical landmarks for SI.
事件相关光信号（EROS）利用近红外光来研究神经元光学特性在对刺激和内源性事件作出反应时的变化。从7名受试者的80个通道收集了EROS对1、5和8赫兹正中神经电刺激的反应。通过将数字化光纤位置与每个受试者的结构磁共振图像（MRI）分别进行配准，对光学记录通道进行空间对齐。然后将配准后的数据集转换到Talairach空间，以便在不同受试者之间进行对齐。对齐后，将来自表面投影像素下方通道的数据进行合并，以生成Z统计量图。在三种刺激频率下，比较了初级体感（SI）皮层手部区域先验感兴趣区域（ROI）内体素相关的波形。在所有三种频率条件下，早在刺激后16 - 32毫秒时，SI中就发现了可靠的光传播时间早期增加（即相位延迟增加），并且在更长潜伏期时，SI上观察到相位延迟增加和信号强度降低。对8赫兹条件的对半分析证明了反应的可重复性。这是对体感反应这些成分的强度和延迟测量的首次直接比较；此外，它表明这些早期皮层成分在不同受试者之间是可重复的，并且与SI的个体受试者解剖标志非常吻合。
