Law Phillip C F, Miller Steven M, Ngo Trung T
Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and The Alfred Hospital, Melbourne, Australia.
Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and The Alfred Hospital, Melbourne, Australia; School of Psychological Sciences, Monash University, Melbourne, Australia.
Physiol Behav. 2017 Nov 1;181:127-136. doi: 10.1016/j.physbeh.2017.08.023. Epub 2017 Aug 30.
Binocular rivalry (BR) occurs when conflicting images concurrently presented to corresponding retinal locations of each eye stochastically alternate in perception. Anomalies of BR rate have been examined in a range of clinical psychiatric conditions. In particular, slow BR rate has been proposed as an endophenotype for bipolar disorder (BD) to improve power in large-scale genome-wide association studies. Examining the validity of BR rate as a BD endophenotype however requires large-scale datasets (n=1000s to 10,000s), a standardized testing protocol, and optimization of stimulus parameters to maximize separation between BD and healthy groups. Such requirements are indeed relevant to all clinical psychiatric BR studies. Here we address the issue of stimulus optimization by examining the effect of stimulus parameter variation on BR rate and mixed-percept duration (MPD) in healthy individuals. We aimed to identify the stimulus parameters that induced the fastest BR rates with the least MPD. Employing a repeated-measures within-subjects design, 40 healthy adults completed four BR tasks using orthogonally drifting grating stimuli that varied in drift speed and aperture size. Pairwise comparisons were performed to determine modulation of BR rate and MPD by these stimulus parameters, and individual variation of such modulation was also assessed. From amongst the stimulus parameters examined, we found that 8cycles/s drift speed in a 1.5° aperture induced the fastest BR rate without increasing MPD, but that BR rate with this stimulus configuration was not substantially different to BR rate with stimulus parameters we have used in previous studies (i.e., 4cycles/s drift speed in a 1.5° aperture). In addition to contributing to stimulus optimization issues, the findings have implications for Levelt's Proposition IV of binocular rivalry dynamics and individual differences in such dynamics.
当同时呈现给每只眼睛相应视网膜位置的冲突图像在感知中随机交替时，就会发生双眼竞争（BR）。在一系列临床精神疾病中，已经对BR速率异常进行了研究。特别是，慢BR速率已被提议作为双相情感障碍（BD）的一种内表型，以提高大规模全基因组关联研究的效能。然而，要检验BR速率作为BD内表型的有效性，需要大规模数据集（n = 1000至10000）、标准化测试方案以及刺激参数的优化，以最大程度地分离BD组和健康组。这些要求确实适用于所有临床精神科BR研究。在这里，我们通过研究刺激参数变化对健康个体BR速率和混合感知持续时间（MPD）的影响来解决刺激优化问题。我们旨在确定能以最少的MPD诱导最快BR速率的刺激参数。采用重复测量的被试内设计，40名健康成年人使用在漂移速度和孔径大小上有所变化的正交漂移光栅刺激完成了四项BR任务。进行成对比较以确定这些刺激参数对BR速率和MPD的调节作用，并且还评估了这种调节的个体差异。在所研究的刺激参数中，我们发现1.5°孔径下8个周期/秒的漂移速度能诱导最快的BR速率且不增加MPD，但这种刺激配置下的BR速率与我们先前研究中使用的刺激参数（即1.5°孔径下4个周期/秒的漂移速度）诱导的BR速率没有实质性差异。除了有助于解决刺激优化问题外，这些发现还对双眼竞争动力学的Levelt命题IV以及这种动力学中的个体差异具有启示意义。
