Piedimonte Alessandro, Volpino Valeria, Campaci Francesco, Deplano Martina, Borghesi Francesca, Pollo Antonella, Carlino Elisa
"Rita Levi Montalcini" Department of Neurosciences, University of Turin, Turin, Italy.
Istituto Auxologico Italiano, IRCCS, U.O. di Neurologia e Neuroriabilitazione, Ospedale San Giuseppe, Piancavallo, Italy.
J Physiol. 2024 Dec;602(24):6925-6939. doi: 10.1113/JP287222. Epub 2024 Oct 9.
Placebo and nocebo effects modulate symptom perception through expectations and learning processes in various domains. Predominantly, their impact has been investigated on pain and physical performance. However, the influence of placebos and nocebos on visual system functionality has yet to be explored. The present study aimed to test whether placebo and nocebo effects can intervene in altering participants' performance outcomes during a novel visual accuracy task and to examine the underlying neural mechanisms through EEG. After performing a baseline session, visual accuracy was said to be enhanced or disrupted by a sham transcranial electrical stimulation over the occipital lobe. Behavioural results showed a significant increase in visual accuracy for the placebo group, from the baseline session to the test session, whereas the nocebo group showed a decrease in visual accuracy. EEG analyses on the event-related potential P300 component, conducted on both a centro-parietal electrode patch and a parieto-occipital, one displayed an increase in the amplitude of P300 for the placebo group, and a decrease in the nocebo group. These findings suggest for the first time that placebo and nocebo effects can influence visual perception and attentional processes linked to it. Overall, the present study contributes to understanding how expectations affect sensory perception beyond pain and the motor system, paving the way for investigating these phenomena in other sensory modalities such as auditory or olfactory perception. KEY POINTS: Placebo and nocebo effects have been studied predominantly in pain and motor performance fields. In a novel visual task, the impact of placebo and nocebo effects on the visual system has been evaluated, in both early components (stimuli-related) and late components (attention-related). The placebo group showed an increase in visual accuracy and EEG-evoked potential amplitudes, whereas the nocebo group showed a decrease in both. This study shows how expectations and the related placebo and nocebo effects can shape basic stimuli sensory perception in the visual domain.
安慰剂和反安慰剂效应通过各个领域的期望和学习过程调节症状感知。主要地，它们对疼痛和身体表现的影响已得到研究。然而，安慰剂和反安慰剂对视觉系统功能的影响尚未得到探索。本研究旨在测试安慰剂和反安慰剂效应是否能在一项新的视觉准确性任务中干预改变参与者的表现结果，并通过脑电图检查潜在的神经机制。在进行基线测试后，通过对枕叶进行假经颅电刺激，称视觉准确性得到提高或受到干扰。行为结果显示，从基线测试到测试阶段，安慰剂组的视觉准确性显著提高，而反安慰剂组的视觉准确性下降。对中央顶叶电极片和顶枕叶进行的事件相关电位P300成分的脑电图分析显示，安慰剂组P300波幅增加，反安慰剂组P300波幅降低。这些发现首次表明，安慰剂和反安慰剂效应可以影响视觉感知以及与之相关的注意力过程。总体而言，本研究有助于理解期望如何影响除疼痛和运动系统之外的感觉感知，为在其他感觉模态（如听觉或嗅觉感知）中研究这些现象铺平了道路。关键点：安慰剂和反安慰剂效应主要在疼痛和运动表现领域得到研究。在一项新的视觉任务中，评估了安慰剂和反安慰剂效应在早期成分（刺激相关）和晚期成分（注意力相关）对视觉系统的影响。安慰剂组视觉准确性和脑电图诱发电位波幅增加，而反安慰剂组两者均下降。这项研究表明期望以及相关的安慰剂和反安慰剂效应如何塑造视觉领域的基本刺激感觉感知。
