Event-related fast optical signal in a rapid object recognition task: improving detection by the independent component analysis.
Event-related fast optical signal in a rapid object recognition task: improving detection by the independent component analysis.
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DOI：
10.1016/j.brainres.2008.07.122
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发表时间：
2008-10-21
期刊：
影响因子：
2.9
通讯作者：
VanMeter, John
中科院分区：
文献类型：
--
作者：
Medvedev, Andrei V.;Kainerstorfer, Jana;Borisov, Sergey V.;Barbour, Randall L.;VanMeter, John
关键词：
由于信噪比相对较低，无创记录可能反映神经元活动的快速光信号是一项具有挑战性的任务。为了改善快速物体识别任务中这些信号的检测，我们使用独立分量分析（ICA）来减少“全局干扰”（心跳和表面层的贡献）。我们使用连续波仪器（DYNOT，NIRx，布鲁克林，纽约）记录了 10 名惯用右手的参与者的左前额叶皮层的光学信号。视觉刺激是以各种车辆为目标的城市、风景和海滨场景的图片（目标与非目标比率1:6），以ISI = 166 ms或250 ms呈现。受试者在心里计算目标。数据以 2–30 Hz 进行过滤，并使用 ICA 权重矩阵（对于浅层）通过视觉识别（针对心跳）人工成分。从 ICA 分量中恢复光信号，并去除人为分量，然后在目标和非目标历元上进行平均。经过 ICA 处理后，70-100% 的受试者检测到了与事件相关的反应。精细化信号显示，在达到目标后 200-300 毫秒内，信号较基线显着下降，在非目标后略有增加。光信号的时间分布与“差异 ERP 响应”的分布很好地对应，“差异 ERP 响应”是目标与非目标之间的差异，在类似的物体检测任务中在 200 毫秒处达到峰值。这些结果表明，通过能够消除噪声、全局干扰和表面层活动的 ICA 方法，可以改进连续波仪器对快速光学响应的检测。快速光信号可以提供有关高阶认知任务（例如对象快速分类）期间大脑处理的更多信息。
Noninvasive recording of fast optical signals presumably reflecting neuronal activity is a challenging task because of a relatively low signal-to-noise ratio. To improve detection of those signals in rapid object recognition tasks, we used the Independent Component Analysis (ICA) to reduce “global interference” (heartbeat and contribution of superficial layers). We recorded optical signals from the left prefrontal cortex in 10 right-handed participants with a continuous-wave instrument (DYNOT, NIRx, Brooklyn, NY). Visual stimuli were pictures of urban, landscape and seashore scenes with various vehicles as targets (target-to-non-target ratio 1:6) presented at ISI = 166 ms or 250 ms. Subjects mentally counted targets. Data were filtered at 2–30 Hz and artifactual components were identified visually (for heartbeat) and using the ICA weight matrix (for superficial layers). Optical signals were restored from the ICA components with artifactual components removed and then averaged over target and non-target epochs. After ICA processing, the event-related response was detected in 70–100% of subjects. The refined signal showed a significant decrease from baseline within 200–300 ms after targets and a slight increase after non-targets. The temporal profile of the optical signal corresponded well to the profile of a “differential ERP response”, the difference between targets and non-targets which peaks at 200 ms in similar object detection tasks. These results demonstrate that the detection of fast optical responses with continuous-wave instruments can be improved through the ICA method capable to remove noise, global interference and the activity of superficial layers. Fast optical signals may provide further information on brain processing during higher-order cognitive tasks such as rapid categorization of objects.
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