Sandberg Kristian, Barnes Gareth Robert, Bahrami Bahador, Kanai Ryota, Overgaard Morten, Rees Geraint
Cognitive Neuroscience Research Unit, Hammel Rehabilitation and Research Center, Voldbyvej 15, 8450 Hammel, Denmark; Cognitive Neuroscience Research Unit, Aarhus University Hospital, Noerrebrogade 44, Building 10G, 8000 Aarhus C, Denmark; Institute of Cognitive Neuroscience, University College London, 17 Queen Square, WC1N 3AR London, United Kingdom.
Wellcome Trust Centre for Neuroimaging, Institute of Neurology, 12 Queen Square, WC1N 3AR London, United Kingdom.
Neuroimage. 2014 Oct 15;100:161-75. doi: 10.1016/j.neuroimage.2014.06.023. Epub 2014 Jun 16.
During binocular rivalry, visual perception alternates spontaneously between two different monocular images. Such perceptual reversals are slowed or halted if stimuli are presented intermittently with inter-stimulus intervals larger than ~400 ms--a phenomenon called stabilization. Often, the neural correlates of reversal and stabilization are studied separately, and both phenomena in turn are studied separately from the neural correlates of conscious perception. To distinguish the neural correlates of perceptual content, stabilization and reversal, we recorded MEG signals associated with each in the same group of healthy humans observing repeated trials of intermittent presentation of a dichoptic stimulus. Perceptual content correlated mainly with modulation of stimulus-specific activity in occipital/temporal areas 150-270 ms after stimulus onset, possibly reflecting inhibition of the neural populations representing the suppressed image. Stability of perception reflected a gradual build-up of this modulation across at least 10 trials and was also, to some extent, associated with parietal activity 40-90 ms and 220-270 ms after stimulus onset. Perceptual reversals, in contrast, were associated with parietal (150-270 ms) and temporal (150-210 ms) activity on the trial before the reversal and a gradual change in perception-specific activity in occipital (150-270 ms) and temporal (220-420 ms) areas across at least 10 trials leading up to a reversal. Mechanistically, these findings suggest that stability of perception during rivalry is maintained by modulation of activity related to the two monocular images, and gradual adaptation of neuronal populations leads to instability that is eventually resolved by signals from parietal and late sensory cortices.
在双眼竞争期间，视觉感知会在两个不同的单眼图像之间自发交替。如果刺激以大于约400毫秒的刺激间隔间歇性呈现，这种感知反转会减慢或停止——这一现象称为稳定化。通常，反转和稳定化的神经关联是分开研究的，而且这两种现象又分别与意识感知的神经关联分开研究。为了区分感知内容、稳定化和反转的神经关联，我们在同一组健康人类中记录了与每次现象相关的脑磁图（MEG）信号，这些人观察了重复试验的双眼刺激间歇性呈现。感知内容主要与刺激开始后150 - 270毫秒枕叶/颞叶区域中刺激特异性活动的调制相关，这可能反映了对代表被抑制图像的神经群体的抑制。感知的稳定性反映了这种调制在至少10次试验中的逐渐增强，并且在某种程度上也与刺激开始后40 - 90毫秒和220 - 270毫秒的顶叶活动相关。相比之下，感知反转与反转前试验中的顶叶（150 - 270毫秒）和颞叶（150 - 210毫秒）活动以及在至少10次导致反转的试验中枕叶（150 - 270毫秒）和颞叶（220 - 420毫秒）区域中感知特异性活动的逐渐变化相关。从机制上讲，这些发现表明，竞争期间感知的稳定性是通过与两个单眼图像相关的活动调制来维持的，神经元群体的逐渐适应导致不稳定性，最终由顶叶和晚期感觉皮层的信号解决。
