Philiastides Marios G, Sajda Paul
Laboratory for Intelligent Imaging and Neural Computing, Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
Cereb Cortex. 2006 Apr;16(4):509-18. doi: 10.1093/cercor/bhi130. Epub 2005 Jul 13.
Single and multi-unit recordings in primates have identified spatially localized neuronal activity correlating with an animal's behavioral performance. Due to the invasive nature of these experiments, it has been difficult to identify such correlates in humans. We report the first non-invasive neural measurements of perceptual decision making, via single-trial EEG analysis, that lead to neurometric functions predictive of psychophysical performance for a face versus car categorization task. We identified two major discriminating components. The earliest correlating with psychophysical performance was consistent with the well-known face-selective N170. The second component, which was a better match to the psychometric function, did not occur until at least 130 ms later. As evidence for faces versus cars decreased, onset of the later, but not the earlier, component systematically shifted forward in time. In addition, a choice probability analysis indicated strong correlation between the neural responses of the later component and our subjects' behavioral judgements. These findings demonstrate a temporal evolution of component activity indicative of an evidence accumulation process which begins after early visual perception and has a processing time that depends on the strength of the evidence.
在灵长类动物中进行的单单元和多单元记录已识别出与动物行为表现相关的空间局部神经元活动。由于这些实验具有侵入性，因此很难在人类中识别出此类相关性。我们报告了首次通过单试次脑电图分析对感知决策进行的非侵入性神经测量，该测量得出了神经测量函数，可预测面部与汽车分类任务中的心理物理表现。我们识别出两个主要的区分成分。最早与心理物理表现相关的成分与著名的面部选择性N170一致。第二个成分与心理测量函数更匹配，至少在130毫秒后才出现。随着面部与汽车的证据减少，较晚出现的成分（而非较早出现的成分）的起始时间系统地提前。此外，选择概率分析表明，较晚出现的成分的神经反应与我们受试者的行为判断之间存在强烈相关性。这些发现证明了成分活动的时间演变，这表明证据积累过程在早期视觉感知之后开始，并且其处理时间取决于证据的强度。
