Marshev Vasilii, Frey Haley G, Brascamp Jan
Michigan State University, East Lansing, MI, USA.
https://orcid.org/0000-0002-7251-6749.
J Vis. 2025 Aug 1;25(10):7. doi: 10.1167/jov.25.10.7.
The pupil constricts in response to visual stimuli that keep net luminance unchanged but that do introduce local luminance increments and decrements-a reaction here called "isoluminant constriction." This response can form a pupillometric index of visual processing, but it is unclear what kind of processing it reflects; some authors have suggested that the constriction arises from subcortical, luminance-based neural signals, whereas others have argued for an origin at cortical, feature-based processing stages. We tested the involvement of cortical neural activity in isoluminant constrictions. To this end, we measured constrictions to stimuli presented after contrast adaptation, an adaptation procedure thought to lessen cortical stimulus responses. If cortical processing is involved in the isoluminant constriction, then such adaptation should lead to reduced isoluminant constriction amplitudes. We tested this prediction in the course of three experiments. We found no evidence for the prediction in any of the experiments, and did find Bayesian evidence against the prediction. These results suggest that, at least in the conditions of our experiments, isoluminant constrictions may not reflect visual cortical processing.
瞳孔会对视觉刺激做出收缩反应，这些视觉刺激虽保持净亮度不变，但会引起局部亮度的增加和减少——这种反应在此被称为“等亮度收缩”。这种反应可形成视觉处理的瞳孔测量指标，但尚不清楚它反映的是何种处理过程；一些作者认为收缩源于基于亮度的皮层下神经信号，而另一些人则主张其起源于基于特征的皮层处理阶段。我们测试了皮层神经活动在等亮度收缩中的参与情况。为此，我们测量了对对比度适应后呈现的刺激的收缩反应，对比度适应是一种旨在减少皮层刺激反应的适应程序。如果皮层处理参与等亮度收缩，那么这种适应应会导致等亮度收缩幅度减小。我们在三个实验过程中测试了这一预测。我们在任何一个实验中都未找到支持该预测的证据，并且确实发现了贝叶斯证据反对该预测。这些结果表明，至少在我们的实验条件下，等亮度收缩可能并不反映视觉皮层处理。
