Dowiasch Stefan, Blohm Gunnar, Bremmer Frank
Department of Neurophysics, Philipps-University Marburg, Karl-von-Frisch-Straße 8a, 35043, Marburg, Germany.
Queen's University, Kingston, ON, Canada.
Eur J Neurosci. 2016 Jul;44(2):1846-55. doi: 10.1111/ejn.13276. Epub 2016 Jun 12.
The dependence of neuronal discharge on the position of the eyes in the orbit is a functional characteristic of many visual cortical areas of the macaque. It has been suggested that these eye-position signals provide relevant information for a coordinate transformation of visual signals into a non-eye-centered frame of reference. This transformation could be an integral part for achieving visual perceptual stability across eye movements. Previous studies demonstrated close to veridical eye-position decoding during stable fixation as well as characteristic erroneous decoding across saccadic eye-movements. Here we aimed to decode eye position during smooth pursuit. We recorded neural activity in macaque area VIP during steady fixation, saccades and smooth-pursuit and investigated the temporal and spatial accuracy of eye position as decoded from the neuronal discharges. Confirming previous results, the activity of the majority of neurons depended linearly on horizontal and vertical eye position. The application of a previously introduced computational approach (isofrequency decoding) allowed eye position decoding with considerable accuracy during steady fixation. We applied the same decoder on the activity of the same neurons during smooth-pursuit. On average, the decoded signal was leading the current eye position. A model combining this constant lead of the decoded eye position with a previously described attentional bias ahead of the pursuit target describes the asymmetric mislocalization pattern for briefly flashed stimuli during smooth pursuit eye movements as found in human behavioral studies.
神经元放电对眼睛在眼眶中位置的依赖性是猕猴许多视觉皮层区域的一个功能特征。有人提出,这些眼位信号为将视觉信号转换为非眼中心参考系提供了相关信息。这种转换可能是实现眼动过程中视觉感知稳定性的一个组成部分。先前的研究表明,在稳定注视期间能实现近乎真实的眼位解码,以及在扫视眼动过程中存在特征性的错误解码。在这里,我们旨在解码平稳跟踪过程中的眼位。我们记录了猕猴VIP区在稳定注视、扫视和平稳跟踪期间的神经活动,并研究了从神经元放电中解码出的眼位的时间和空间准确性。与先前结果一致,大多数神经元的活动在水平和垂直眼位上呈线性依赖。应用先前引入的一种计算方法(等频率解码),在稳定注视期间能够以相当高的准确性进行眼位解码。我们将相同的解码器应用于平稳跟踪期间相同神经元的活动。平均而言,解码信号领先于当前眼位。一个将解码眼位的这种恒定领先与先前描述的在跟踪目标之前的注意力偏差相结合的模型,描述了人类行为研究中发现的平稳跟踪眼动期间短暂闪现刺激的不对称错误定位模式。