Institute of Psychology, Experimental Psychology II and Biological Psychology, University of Osnabrück, D-49074, Osnabrück, Germany.
Department of Psychology and Center for the Study of Emotion and Attention, University of Florida, Gainesville, Florida, 32611, USA.
Sci Rep. 2020 Mar 3;10(1):3926. doi: 10.1038/s41598-020-60597-z.
Neurons in the visual cortex sharpen their orientation tuning as humans learn aversive contingencies. A stimulus orientation (CS+) that reliably predicts an aversive noise (unconditioned stimulus: US) is selectively enhanced in lower-tier visual cortex, while similar unpaired orientations (CS-) are inhibited. Here, we examine in male volunteers how sharpened visual processing is affected by fear extinction learning (where no US is presented), and how fear and extinction memory undergo consolidation one day after the original learning episode. Using steady-state visually evoked potentials from electroencephalography in a fear generalization task, we found that extinction learning prompted rapid changes in orientation tuning: Both conditioned visuocortical and skin conductance responses to the CS+ were strongly reduced. Next-day re-testing (delayed recall) revealed a brief but precise return-of-tuning to the CS+ in visual cortex accompanied by a brief, more generalized return-of-fear in skin conductance. Explorative analyses also showed persistent tuning to the threat cue in higher visual areas, 24 h after successful extinction, outlasting peripheral responding. Together, experience-based changes in the sensitivity of visual neurons show response patterns consistent with memory consolidation and spontaneous recovery, the hallmarks of long-term neural plasticity.
在人类学习厌恶条件反射时,视觉皮层中的神经元会增强其朝向调谐。当一个刺激朝向(CS+)可靠地预测到一个厌恶的噪音(非条件刺激:US)时,它会在较低层次的视觉皮层中被选择性地增强,而类似的未配对的朝向(CS-)则被抑制。在这里,我们在男性志愿者中研究了经过恐惧消退学习(没有呈现 US)后,视觉处理的锐度如何受到影响,以及恐惧和消退记忆在最初学习后的一天如何进行巩固。在恐惧泛化任务中使用脑电图的稳态视觉诱发电位,我们发现消退学习促使朝向调谐发生快速变化:CS+的条件视觉皮层和皮肤电导率反应都强烈降低。第二天的重新测试(延迟回忆)显示,视觉皮层中 CS+的调谐短暂但精确地恢复,同时皮肤电导率中的恐惧反应也短暂但更普遍地恢复。探索性分析还表明,在成功消退 24 小时后,在更高的视觉区域中仍然存在对威胁线索的持续调谐,这持续时间长于外周反应。总的来说,基于经验的视觉神经元敏感性变化表现出与记忆巩固和自发恢复一致的反应模式,这是长期神经可塑性的特征。