Davidson Matthew J, Graafsma Irene L, Tsuchiya Naotsugu, van Boxtel Jeroen
School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia.
Department of Psychology, University of Amsterdam, Amsterdam 1001 NK, the Netherlands.
Neurosci Conscious. 2020 Apr 12;2020(1):niaa002. doi: 10.1093/nc/niaa002. eCollection 2020.
Perceptual filling-in (PFI) occurs when a physically present visual target disappears from conscious perception, with its location filled-in by the surrounding visual background. These perceptual changes are complete, near instantaneous, and can occur for multiple separate locations simultaneously. Here, we show that contrasting neural activity during the presence or absence of multi-target PFI can complement other findings from multistable phenomena to reveal the neural correlates of consciousness (NCC). We presented four peripheral targets over a background dynamically updating at 20 Hz. While participants reported on target disappearances/reappearances via button press/release, we tracked neural activity entrained by the background during PFI using steady-state visually evoked potentials (SSVEPs) recorded in the electroencephalogram. We found background SSVEPs closely correlated with subjective report, and increased with an increasing amount of PFI. Unexpectedly, we found that as the number of filled-in targets increased, the duration of target disappearances also increased, suggesting that facilitatory interactions exist between targets in separate visual quadrants. We also found distinct spatiotemporal correlates for the background SSVEP harmonics. Prior to genuine PFI, the response at the second harmonic (40 Hz) increased before the first (20 Hz), which we tentatively link to an attentional effect, while no such difference between harmonics was observed for physically removed stimuli. These results demonstrate that PFI can be used to study multi-object perceptual suppression when frequency-tagging the background of a visual display, and because there are distinct neural correlates for endogenously and exogenously induced changes in consciousness, that it is ideally suited to study the NCC.
当一个实际存在的视觉目标从意识感知中消失，其位置被周围的视觉背景填充时，就会发生感知填充（PFI）。这些感知变化是完整的、几乎瞬间发生的，并且可以同时在多个不同位置出现。在这里，我们表明，在多目标PFI出现或不出现期间对比神经活动，可以补充多稳态现象的其他发现，以揭示意识的神经相关物（NCC）。我们在以20Hz动态更新的背景上呈现了四个周边目标。当参与者通过按下/释放按钮报告目标的消失/重新出现时，我们使用脑电图记录的稳态视觉诱发电位（SSVEP）跟踪PFI期间被背景夹带的神经活动。我们发现背景SSVEP与主观报告密切相关，并且随着PFI量的增加而增加。出乎意料的是，我们发现随着填充目标数量的增加，目标消失的持续时间也增加，这表明在不同视觉象限中的目标之间存在促进性相互作用。我们还发现了背景SSVEP谐波的不同时空相关性。在真正的PFI之前，二次谐波（40Hz）的反应在一次谐波（20Hz）之前增加，我们初步将其与注意力效应联系起来，而对于物理移除的刺激，谐波之间没有观察到这种差异。这些结果表明，当对视觉显示背景进行频率标记时，PFI可用于研究多物体感知抑制，并且由于内源性和外源性诱导的意识变化存在不同的神经相关性，因此它非常适合研究NCC。
