Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK.
Neuroscience and Behaviour Laboratory, Istituto Italiano di Tecnologia, 00161 Rome, Italy.
Cereb Cortex. 2021 Jan 5;31(2):949-960. doi: 10.1093/cercor/bhaa267.
Living in rapidly changing environments has shaped the mammalian brain toward high sensitivity to abrupt and intense sensory events-often signaling threats or affordances requiring swift reactions. Unsurprisingly, such events elicit a widespread electrocortical response (the vertex potential, VP), likely related to the preparation of appropriate behavioral reactions. Although the VP magnitude is largely determined by stimulus intensity, the relative contribution of the differential and absolute components of intensity remains unknown. Here, we dissociated the effects of these two components. We systematically varied the size of abrupt intensity increases embedded within continuous stimulation at different absolute intensities, while recording brain activity in humans (with scalp electroencephalography) and rats (with epidural electrocorticography). We obtained three main results. 1) VP magnitude largely depends on differential, and not absolute, stimulus intensity. This result held true, 2) for both auditory and somatosensory stimuli, indicating that sensitivity to differential intensity is supramodal, and 3) in both humans and rats, suggesting that sensitivity to abrupt intensity differentials is phylogenetically well-conserved. Altogether, the current results show that these large electrocortical responses are most sensitive to the detection of sensory changes that more likely signal the sudden appearance of novel objects or events in the environment.
生活在快速变化的环境中，使得哺乳动物的大脑对突然而强烈的感觉事件高度敏感——这些事件通常是威胁或提供需要迅速反应的机会的信号。毫不奇怪，这种事件会引发广泛的皮层电反应（顶点电位，VP），这可能与适当的行为反应准备有关。尽管 VP 的幅度在很大程度上取决于刺激强度，但强度的差异和绝对成分的相对贡献仍然未知。在这里，我们将这两个成分的作用分开。我们系统地改变了在不同绝对强度下的连续刺激中嵌入的突然强度增加的大小，同时在人类（头皮脑电图）和大鼠（硬膜外皮层电图）中记录大脑活动。我们得到了三个主要结果。1）VP 的幅度主要取决于差异，而不是绝对的刺激强度。这一结果在听觉和体感刺激中均成立，表明对差异强度的敏感性是超模态的，并且 3）在人类和大鼠中均成立，表明对突然强度差异的敏感性在系统发育上得到了很好的保守。总之，目前的结果表明，这些大的皮层电反应对检测更可能表明环境中突然出现新物体或事件的感觉变化最为敏感。
