CEREBRAL CORTICAL MECHANISMS FOR EYE MOVEMENTS AND VISUAL ATTENTION

两条调查路线被遵循，以确定大脑如何 皮质及其传出区域控制眼球运动， 视觉空间注意力 单神经元记录被用来探索机制， 猴子的顶叶皮层分析空间。 先前实验 在这个实验室里证明顶叶皮层的神经元 在坐标系中描述视觉环境， 是人们目光的中心 然而，在猴子进行扫视之前， 刺激将进入一个神经元的感受野凭借 即将到来扫视可以刺激神经元， 目前不在刺激通常可以 刺激神经元。 这种坐标系移动的现象 已经扩展到减缓眼球运动。 猴子被训练成 通过平滑的追踪，或通过 当动物旋转时抑制前庭眼反射 以与刺激相同的速度。 在这两种情况下，当眼睛移动时， 最近消失的刺激的空间位置 在神经元的感受野中，许多顶叶神经元放电 尽管事实上，当刺激闪光时， 感受野 这种感受野的机制 解释了大脑如何在空间上产生精确的运动， 人类或猴子在环境中移动， 等待视网膜的表现重新建立在 大脑皮层在眼睛在太空中移动后的变化。 虽然顶叶皮层的神经元放电之前， 视觉引导的眼球运动，尚不清楚这是否 反应与扫视目标引起的注意有关， 或进行扫视的意图。 为了区分这两者 为了验证这种可能性，猴子接受了反扫视任务的训练。 猴子 我先看一个固定点，这个固定点可能是红色的， 或绿色。 当固定灯为红色时，猴子随后 进行扫视以获取闪烁的目标。 当固定光 是绿色时，猴子们向相反的方向扫视， 闪光的目标，但与目标相同的距离。 的 大多数顶叶神经元对视觉刺激有反应， 它决定了一个朝向或远离它的扫视。一些细胞做出了反应 但是当一个相反的刺激决定了一个扫视时， 刺激的空间位置。 最不常见的细胞类型 只有扫视方向的信息 这些数据显示 顶叶皮层中的大多数神经元描述了一个视觉 刺激和对刺激的关注。 几个细胞 唯一描述运动方向。

Two lines of inquiry were followed to determine how the cerebral cortex and its efferent regions control eye movements and visuospatial attention. Single neuron recording was used to probe the mechanisms whereby the parietal cortex of the monkey analyzes space. Previous experiments in this laboratory demonstrated that neurons in parietal cortex describe the visual environment in a coordinate system whose origin is the center of gaze. Before a monkey makes a saccade, however, stimuli that will enter the receptive field of a neuron by virtue of the impending saccade can excite that neuron even though they are currently not in a retinal location in which stimuli can normally excite the neuron. This phenomenon of the coordinate system shift has been extended to slow eye movements. Monkeys were trained to follow a slowly moving visual stimulus by smooth pursuit, or by suppression of the vestibuloocular reflex when the animal is rotated at the same speed as the stimulus. In both cases when the eye moves the spatial location of a recently vanished stimulus into the receptive field of the neuron, many parietal neurons discharge despite the fact that when the stimulus flashed it was not in their receptive fields. This mechanism of receptive field shifts now explains how the brain can generate spatially accurate movements when a human or monkey moves through its environment, without having to wait for the retinal representation to reestablish itself in the cerebral cortex after the eyes have moved in space. Although neurons in the parietal cortex discharge before visually-guided accadic eye movements, it has not been clear if this response is related to the attention that the saccade target evokes, or the intention to make the saccade. To distinguish between this possibility, monkeys were trained on an anti-saccade task. Monkeys began the task by looking at a fixation spot that could be either red or green. When the fixation light was red, the monkeys subsequently made a saccade to acquire a flashed target. When the fixation light was green, the monkeys made a saccade in the opposite direction from the flashed target, but of the same distance as the target. The majority of parietal neurons responded to the visual stimulus whether it dictated a saccade toward or away from it. A few cells responded to the stimulus but also when an opposite stimulus dictated a saccade to the spatial location of the stimulus. The least common cell type only had information about the saccade direction. These data show that the majority of neurons in the parietal cortex describe a visual stimulus and the attention drawn to that stimulus. Few cells describe movement direction uniquely.