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How do the blind 'see'? The role of spontaneous brain activity in self-generated perception.

盲人如何 “看”?自发大脑活动在自我生成感知中的作用。

  • 影响因子:7.52
  • DOI:10.1093/brain/awaa384
  • 作者列表:"Hahamy A","Wilf M","Rosin B","Behrmann M","Malach R
  • 发表时间:2021-02-12
Abstract

:Spontaneous activity of the human brain has been well documented, but little is known about the functional role of this ubiquitous neural phenomenon. It has previously been hypothesized that spontaneous brain activity underlies unprompted (internally generated) behaviour. We tested whether spontaneous brain activity might underlie internally-generated vision by studying the cortical visual system of five blind/visually-impaired individuals who experience vivid visual hallucinations (Charles Bonnet syndrome). Neural populations in the visual system of these individuals are deprived of external input, which may lead to their hyper-sensitization to spontaneous activity fluctuations. To test whether these spontaneous fluctuations can subserve visual hallucinations, the functional MRI brain activity of participants with Charles Bonnet syndrome obtained while they reported their hallucinations (spontaneous internally-generated vision) was compared to the: (i) brain activity evoked by veridical vision (externally-triggered vision) in sighted controls who were presented with a visual simulation of the hallucinatory streams; and (ii) brain activity of non-hallucinating blind controls during visual imagery (cued internally-generated vision). All conditions showed activity spanning large portions of the visual system. However, only the hallucination condition in the Charles Bonnet syndrome participants demonstrated unique temporal dynamics, characterized by a slow build-up of neural activity prior to the reported onset of hallucinations. This build-up was most pronounced in early visual cortex and then decayed along the visual hierarchy. These results suggest that, in the absence of external visual input, a build-up of spontaneous fluctuations in early visual cortex may activate the visual hierarchy, thereby triggering the experience of vision.

摘要

: 人类大脑的自发活动已被充分记录,但对这种普遍存在的神经现象的功能作用知之甚少。以前曾假设自发的大脑活动是自发 (内部产生的) 行为的基础。我们通过研究经历生动视觉幻觉 (Charles Bonnet综合征) 的五名失明/视力受损个体的皮层视觉系统,测试自发性大脑活动是否可能是内部产生的视觉的基础。这些个体的视觉系统中的神经群体被剥夺了外部输入,这可能导致其对自发活动波动的过度致敏。为了测试这些自发的波动是否可以替代视觉幻觉,将查尔斯·博内综合征参与者在报告幻觉时获得的功能性MRI大脑活动 (自发的内部产生的视觉) 与 (i) 由真实视觉诱发的大脑活动 (外部触发的视觉) 进行比较在视觉对照中,他们被呈现幻觉流的视觉模拟; 和 (ii) 视觉想象期间非幻觉盲对照的大脑活动 (提示内部生成的视觉)。所有条件均显示跨越视觉系统的大部分的活动。然而,只有查尔斯·博内综合征参与者的幻觉状况表现出独特的时间动态,其特征是在报告的幻觉发作之前神经活动缓慢积累。这种集结最为明显早期视觉皮层然后腐烂的视觉层次.这些结果表明,在缺乏外部视觉输入的情况下,早期视觉皮层中自发波动的积累可能激活视觉等级,从而触发视觉体验。

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