Kurkin Sergei A, Akao Teppei, Fukushima Junko, Fukushima Kikuro
Department of Physiology, Hokkaido University School of Medicine, West 7, North 15, Sapporo, 060-8638, Japan.
Exp Brain Res. 2007 Feb;176(4):658-64. doi: 10.1007/s00221-006-0830-y. Epub 2007 Jan 10.
The smooth-pursuit system and vestibular system interact to keep the retinal target image on the fovea during head and/or whole body movements. The caudal part of the frontal eye fields (FEF) in the fundus of arcuate sulcus contains pursuit neurons and the majority of them respond to vestibular stimulation induced by whole-body rotation, that activates primarily semi-circular canals, and by whole-body translation, that activates otoliths. To examine whether coordinate frames representing FEF pursuit signals are orbital or earth-vertical, we compared preferred directions during upright and static, whole-body roll-tilt in head- and trunk-restrained monkeys. Preferred directions (re monkeys' head/trunk axis) of virtually all pursuit neurons tested (n = 21) were similar during upright and static whole-body roll-tilt. The slight shift of preferred directions of the majority of neurons could be accounted for by ocular counter-rolling. The mean (+/-SD) differences in preferred directions between upright and 40 degrees right ear down and between upright and 40 degrees left ear down were 6 degrees (+/-6 degrees) and 5 degrees (+/-5 degrees), respectively. Visual motion preferred directions were also similar in five pursuit neurons tested. To examine whether FEF pursuit neurons could signal static whole-body roll-tilt, we compared mean discharge rates of 29 neurons during fixation of a stationary spot while upright and during static, whole-body roll-tilt. Virtually all neurons tested (28/29) did not exhibit a significant difference in mean discharge rates between the two conditions. These results suggest that FEF pursuit neurons do not signal static roll-tilt and that they code pursuit signals in head/trunk-centered coordinates.
在头部和/或全身运动期间，平稳跟踪系统和前庭系统相互作用，以使视网膜目标图像保持在中央凹上。弓形沟底部的额叶眼动区（FEF）的尾部包含跟踪神经元，其中大多数神经元对全身旋转（主要激活半规管）和全身平移（主要激活耳石）所诱发的前庭刺激产生反应。为了研究代表FEF跟踪信号的坐标框架是眼眶的还是地球垂直的，我们比较了在头部和躯干受约束的猴子直立和静态全身侧滚倾斜时的偏好方向。在直立和静态全身侧滚倾斜期间，几乎所有测试的跟踪神经元（n = 21）的偏好方向（相对于猴子的头部/躯干轴）都是相似的。大多数神经元偏好方向的轻微偏移可以用眼球反旋转来解释。直立与右耳向下40度以及直立与左耳向下40度之间偏好方向的平均（±标准差）差异分别为6度（±6度）和5度（±5度）。在测试的五个跟踪神经元中，视觉运动偏好方向也相似。为了研究FEF跟踪神经元是否能发出静态全身侧滚倾斜的信号，我们比较了29个神经元在直立固定静止点期间和静态全身侧滚倾斜期间的平均放电率。几乎所有测试的神经元（28/29）在这两种情况下的平均放电率均无显著差异。这些结果表明，FEF跟踪神经元不发出静态侧滚倾斜的信号，它们以头部/躯干为中心的坐标编码跟踪信号。
