Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom; Faculty of Dentistry, University of Toronto, Toronto, M5G 1G6 Canada.
Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom; Department of Neurology and Psychiatry, Sapienza University of Rome, Rome 00185, Italy.
eNeuro. 2016 Jul 11;3(3). doi: 10.1523/ENEURO.0151-15.2016. eCollection 2016 May-Jun.
Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site.
特征选择在有目标导向行为的背景下得到了广泛的研究，其中它受到自上而下因素的强烈驱动。这种功能的一个更原始的版本是检测环境中刺激特征的自下而上的变化。事实上，神经系统被调整为检测快速上升、强烈的刺激，这些刺激很可能反映威胁，如伤害性体感刺激。这些刺激在头皮顶点产生最大的大脑电位。当用伤害性激光刺激诱发时，这些反应被标记为激光诱发电位（LEP）。尽管已经表明刺激模态的变化和刺激强度的增加会引起大的 LEP，但尚未确定刺激位移是否会影响主要 LEP 波（N1、N2 和 P2）的振幅。在这里，在三个实验中，我们确定了一组人类神经系统遵循的规则，以识别伤害性刺激空间位置的变化。我们表明，N2 波对以下情况敏感：（1）在自我中心坐标中，连续刺激之间的大位移，但不在躯体拓扑坐标中；（2）位移导致刺激位置发生与行为相关的变化。这些发现表明，伤害性诱发的顶点电位对伤害性刺激相对于身体的位置的行为相关变化敏感，并且手是一个特别重要的行为部位。
