Department of Psychology, The University of York, Heslington, York, United Kingdom; Department of Mathematics and Computer Science, Rutgers University Newark, Newark, NJ, USA.
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
Neuroimage. 2018 May 15;172:753-765. doi: 10.1016/j.neuroimage.2018.02.021. Epub 2018 Feb 14.
A neutral density filter placed before one eye will produce a dichoptic imbalance in luminance, which attenuates responses to visual stimuli and lags neural signals from retina to cortex in the filtered eye. When stimuli are presented to both the filtered and unfiltered eye (i.e., binocularly), neural responses show little attenuation and no lag compared with their baseline counterpart. This suggests that binocular visual mechanisms must suppress the attenuated and delayed input from the filtered eye; however, the mechanisms involved remain unclear. Here, we used a Steady-State Visual Evoked Potential (SSVEP) technique to measure neural responses to monocularly and binocularly presented stimuli while observers wore an ND filter in front of their dominant eye. These data were well-described by a binocular summation model, which received the sinusoidal contrast modulation of the stimulus as input. We incorporated the influence of the ND filter with an impulse response function, which adjusted the input magnitude and phase in a biophysically plausible manner. The model captured the increase in attenuation and lag of neural signals for stimuli presented to the filtered eye as a function of filter strength, while also generating the filter phase-invariant responses from binocular presentation for EEG and psychophysical data. These results clarify how binocular visual mechanisms-specifically interocular suppression-can suppress the delayed and attenuated signals from the filtered eye and maintain normal neural signals under imbalanced luminance conditions.
在一只眼睛前放置中性密度滤光片会产生亮度的二向性不平衡，从而减弱对视觉刺激的反应，并延迟从滤过眼的视网膜到皮质的神经信号。当刺激同时呈现给滤过眼和未滤过眼（即双眼）时，与基线相比，神经反应几乎没有衰减，也没有滞后。这表明双眼视觉机制必须抑制来自滤过眼的衰减和延迟输入；然而，所涉及的机制尚不清楚。在这里，我们使用稳态视觉诱发电位（SSVEP）技术来测量观察者在主导眼前佩戴中性密度滤光片时，单眼和双眼呈现刺激的神经反应。这些数据可以很好地用一个双目叠加模型来描述，该模型将刺激的正弦对比度调制作为输入。我们用一个脉冲响应函数来结合中性密度滤光片的影响，该函数以生理上合理的方式调整输入幅度和相位。该模型捕捉到了作为滤光片强度函数的滤过眼呈现刺激的神经信号的衰减和滞后增加，同时还从双眼呈现生成了滤光片相位不变的 EEG 和心理物理数据响应。这些结果阐明了双眼视觉机制（特别是眼间抑制）如何抑制来自滤过眼的延迟和衰减信号，并在亮度不平衡条件下保持正常的神经信号。
