Mifsud Nathan G, Oestreich Lena K L, Jack Bradley N, Ford Judith M, Roach Brian J, Mathalon Daniel H, Whitford Thomas J
School of Psychology, University of New South Wales (UNSW Australia), Sydney, Australia.
Brain Imaging and EEG Laboratory (BIEEGL), Department of Psychiatry, University of California San Francisco, San Francisco, California, USA.
Psychophysiology. 2016 May;53(5):723-32. doi: 10.1111/psyp.12605. Epub 2016 Jan 11.
Self-suppression refers to the phenomenon that sensations initiated by our own movements are typically less salient, and elicit an attenuated neural response, compared to sensations resulting from changes in the external world. Evidence for self-suppression is provided by previous ERP studies in the auditory modality, which have found that healthy participants typically exhibit a reduced auditory N1 component when auditory stimuli are self-initiated as opposed to externally initiated. However, the literature investigating self-suppression in the visual modality is sparse, with mixed findings and experimental protocols. An EEG study was conducted to expand our understanding of self-suppression across different sensory modalities. Healthy participants experienced either an auditory (tone) or visual (pattern-reversal) stimulus following a willed button press (self-initiated), a random interval (externally initiated, unpredictable onset), or a visual countdown (externally initiated, predictable onset-to match the intrinsic predictability of self-initiated stimuli), while EEG was continuously recorded. Reduced N1 amplitudes for self- versus externally initiated tones indicated that self-suppression occurred in the auditory domain. In contrast, the visual N145 component was amplified for self- versus externally initiated pattern reversals. Externally initiated conditions did not differ as a function of their predictability. These findings highlight a difference in sensory processing of self-initiated stimuli across modalities, and may have implications for clinical disorders that are ostensibly associated with abnormal self-suppression.
自我抑制是指与外部世界变化所产生的感觉相比，我们自身运动引发的感觉通常不那么显著，并且引发的神经反应减弱的现象。先前在听觉模态下进行的ERP研究为自我抑制提供了证据，这些研究发现，与外部引发的听觉刺激相比，健康参与者在自我引发听觉刺激时，通常会表现出听觉N1成分的减少。然而，关于视觉模态下自我抑制的文献较少，研究结果和实验方案也各不相同。我们进行了一项脑电图研究，以扩展我们对不同感觉模态下自我抑制的理解。健康参与者在自愿按下按钮（自我引发）、随机间隔（外部引发，不可预测的 onset）或视觉倒计时（外部引发，可预测的 onset，以匹配自我引发刺激的内在可预测性）之后，会经历听觉（音调）或视觉（模式反转）刺激，同时持续记录脑电图。与外部引发的音调相比，自我引发音调的N1振幅降低，表明听觉领域发生了自我抑制。相比之下，与外部引发的模式反转相比，自我引发模式反转的视觉N145成分被放大。外部引发的条件在其可预测性方面没有差异。这些发现突出了不同感觉模态下自我引发刺激的感觉处理差异，可能对表面上与异常自我抑制相关的临床疾病具有启示意义。
