Bogadhi Amarender R, Montagnini Anna, Masson Guillaume S
Institut de Neurosciences de la Timone, CNRS & Aix-Marseille Université, Marseille, France.
J Vis. 2013 Nov 4;13(13):5. doi: 10.1167/13.13.5.
Due to the aperture problem, the initial direction of tracking responses to a translating bar is biased towards the direction orthogonal to the bar. This observation offers a powerful way to explore the interactions between retinal and extraretinal signals in controlling our actions. We conducted two experiments to probe these interactions by briefly (200 and 400 ms) blanking the moving target (45° or 135° tilted bar) during steady state (Experiment 1) and at different moments during the early phase of pursuit (Experiment 2). In Experiment 1, we found a marginal but statistically significant directional bias on target reappearance for all subjects in at least one blank condition (200 or 400 ms). In Experiment 2, no systematic significant directional bias was observed at target reappearance after a blank. These results suggest that the weighting of retinal and extraretinal signals is dynamically modulated during the different phases of pursuit. Based on our previous theoretical work on motion integration, we propose a new closed-loop two-stage recurrent Bayesian model where retinal and extraretinal signals are dynamically weighted based on their respective reliabilities and combined to compute the visuomotor drive. With a single free parameter, the model reproduces many aspects of smooth pursuit observed across subjects during and immediately after target blanking. It provides a new theoretical framework to understand how different signals are dynamically combined based on their relative reliability to adaptively control our actions. Overall, the model and behavioral results suggest that human subjects rely more strongly on prediction during the early phase than in the steady state phase of pursuit.
由于孔径问题,对平移杆的跟踪响应的初始方向偏向于与杆正交的方向。这一观察结果为探索视网膜和视网膜外信号在控制我们行动中的相互作用提供了一种有力的方法。我们进行了两项实验,通过在稳态(实验1)和追踪早期的不同时刻(实验2)短暂(200和400毫秒)遮挡移动目标(45°或135°倾斜杆)来探究这些相互作用。在实验1中,我们发现至少在一种遮挡条件(200或400毫秒)下,所有受试者在目标重新出现时都存在轻微但具有统计学意义的方向偏差。在实验2中,遮挡后目标重新出现时未观察到系统性的显著方向偏差。这些结果表明,在追踪的不同阶段,视网膜和视网膜外信号的权重是动态调制的。基于我们之前关于运动整合的理论工作,我们提出了一种新的闭环两阶段递归贝叶斯模型,其中视网膜和视网膜外信号根据它们各自的可靠性进行动态加权,并结合起来计算视觉运动驱动。该模型仅用一个自由参数就再现了目标遮挡期间和之后受试者观察到的平滑追踪的许多方面。它提供了一个新的理论框架,以理解不同信号如何根据它们的相对可靠性动态组合,从而自适应地控制我们的行动。总体而言,模型和行为结果表明,人类受试者在追踪的早期阶段比稳态阶段更强烈地依赖预测。