Olson C R, Tremblay L
Center for the Neural Basis of Cognition, Mellon Institute, Pittsburgh, Pennsylvania 15213-2683, USA.
J Neurophysiol. 2000 Apr;83(4):2392-411. doi: 10.1152/jn.2000.83.4.2392.
Many neurons in the supplementary eye field (SEF) of the macaque monkey fire at different rates before eye movements to the right or the left end of a horizontal bar regardless of the bar's location in the visual field. We refer to such neurons as carrying object-centered directional signals. The aim of the present study was to throw light on the nature of object-centered direction selectivity by determining whether it depends on the reference image's physical continuity. To address this issue, we recorded from 143 neurons in two monkeys. All of these neurons were located in a region coincident with the SEF as mapped out in previous electrical stimulation studies and many exhibited task-related activity in a standard saccade task. In each neuron, we compared neuronal activity across trials in which the monkey made eye movements to the right or left end of a reference image. On interleaved trials, the reference image might be either a horizontal bar or a pair of discrete dots in a horizontal array. The dominant effect revealed by this experiment was that neurons selectively active before eye movements to the right (or left) end of a bar were also selectively active before eye movements to the right (or left) dot in a horizontal array. An additional minor effect, present in around a quarter of the sample, took the form of a difference in firing rate between bar and dot trials, with the greater level of activity most commonly associated with dot trials. These phenomena could not be accounted for by minor intertrial differences in the physical directions of eye movements. In summary, SEF neurons carry object-centered signals and carry these signals regardless of whether the reference image is physically continuous or disjunct.
猕猴辅助眼区（SEF）中的许多神经元，在眼球向水平条的右端或左端进行眼动之前，无论该条在视野中的位置如何，都会以不同的速率放电。我们将此类神经元称为携带以物体为中心的方向信号。本研究的目的是通过确定以物体为中心的方向选择性是否依赖于参考图像的物理连续性，来阐明其本质。为了解决这个问题，我们记录了两只猴子的143个神经元。所有这些神经元都位于与先前电刺激研究中绘制的SEF重合的区域，并且许多神经元在标准扫视任务中表现出与任务相关的活动。在每个神经元中，我们比较了猴子向参考图像的右端或左端进行眼动的不同试验中的神经元活动。在交错试验中，参考图像可能是水平条或水平排列的一对离散点。该实验揭示的主要效应是，在眼球向水平条的右端（或左端）运动之前选择性活跃的神经元，在眼球向水平排列的右端（或左端）点运动之前也具有选择性活跃。在大约四分之一的样本中存在的另一个较小效应，表现为条试验和点试验之间放电率的差异，其中较高的活动水平最常与点试验相关。这些现象无法用眼球运动物理方向上的微小试验间差异来解释。总之，SEF神经元携带以物体为中心的信号，并且无论参考图像在物理上是连续的还是离散的，都会携带这些信号。
