Bullock Tom, Elliott James C, Serences John T, Giesbrecht Barry
University of California, Santa Barbara.
University of California, San Diego.
J Cogn Neurosci. 2017 Apr;29(4):605-618. doi: 10.1162/jocn_a_01082. Epub 2016 Nov 29.
An organism's current behavioral state influences ongoing brain activity. Nonhuman mammalian and invertebrate brains exhibit large increases in the gain of feature-selective neural responses in sensory cortex during locomotion, suggesting that the visual system becomes more sensitive when actively exploring the environment. This raises the possibility that human vision is also more sensitive during active movement. To investigate this possibility, we used an inverted encoding model technique to estimate feature-selective neural response profiles from EEG data acquired from participants performing an orientation discrimination task. Participants (n = 18) fixated at the center of a flickering (15 Hz) circular grating presented at one of nine different orientations and monitored for a brief shift in orientation that occurred on every trial. Participants completed the task while seated on a stationary exercise bike at rest and during low- and high-intensity cycling. We found evidence for inverted-U effects; such that the peak of the reconstructed feature-selective tuning profiles was highest during low-intensity exercise compared with those estimated during rest and high-intensity exercise. When modeled, these effects were driven by changes in the gain of the tuning curve and in the profile bandwidth during low-intensity exercise relative to rest. Thus, despite profound differences in visual pathways across species, these data show that sensitivity in human visual cortex is also enhanced during locomotive behavior. Our results reveal the nature of exercise-induced gain on feature-selective coding in human sensory cortex and provide valuable evidence linking the neural mechanisms of behavior state across species.
生物体当前的行为状态会影响正在进行的大脑活动。非人类哺乳动物和无脊椎动物的大脑在运动过程中，感觉皮层中特征选择性神经反应的增益会大幅增加，这表明在积极探索环境时，视觉系统会变得更加敏感。这就增加了人类在主动运动时视觉也更敏感的可能性。为了研究这种可能性，我们使用了一种反向编码模型技术，从参与定向辨别任务的受试者采集的脑电图数据中估计特征选择性神经反应谱。受试者（n = 18）注视着以九种不同方向之一呈现的闪烁（15赫兹）圆形光栅的中心，并监测每次试验中出现的短暂方向变化。受试者在静止的健身自行车上休息时以及在低强度和高强度骑行过程中完成任务。我们发现了倒U形效应的证据；与休息和高强度运动期间估计的情况相比，在低强度运动期间重建的特征选择性调谐曲线的峰值最高。建模时，这些效应是由低强度运动相对于休息期间调谐曲线增益和曲线带宽的变化驱动的。因此，尽管不同物种的视觉通路存在巨大差异，但这些数据表明人类视觉皮层在运动行为期间的敏感性也会增强。我们的研究结果揭示了运动诱导的人类感觉皮层特征选择性编码增益的本质，并提供了将跨物种行为状态的神经机制联系起来的宝贵证据。
