Squatrito S, Maioli M G
Department of Physiology, University of Trieste, Italy.
Vis Neurosci. 1996 Mar-Apr;13(2):385-98. doi: 10.1017/s0952523800007628.
The activity of parietal cortex neurones primarily related to eye position (EP neurones) was studied in macaque monkeys with the aim of precisely defining the neurones' gaze fields (GF) and comparing them in two functionally different areas, MSTd and 7a. Discharge rates of single neurones in the inferior parietal lobule and in the underlying cortex of the superior temporal sulcus were recorded in two Java monkeys while the animals fixated a steady visual target positioned at several different points on a video screen. The GFs were then drawn as a regression surface fitting the mean discharge rates. Cells tonically influenced by the angle of gaze were found in both areas. The GFs most often took the form of a nearly planar surface best characterized as a ramp tilted towards a hemifield or quadrant of the visual field, shifted eccentrically with respect to the straight ahead (primary position), and with a midpoint centred between 0 deg and 20 deg of gaze eccentricity and saturation between 10 deg and 35 deg. In a minority of cases, the discharge rate was nearly maximal at the primary position and decreased to a minimum within 35 deg of eccentricity. In other instances, the GFs were peaked surfaces, limited to a restricted part of visual space. EP neurones, while showing similar gaze fields in areas MST and 7a, were found intermingled with functionally different types of cells. The results suggest that EP neurones similar to those already described in several areas of the monkey parietal cortex are present also in area MST. These cells, by signalling the degree of gaze eccentricity from the primary position, encode gaze position in an orbito-centered frame extending up to 30-35 deg from the straight-ahead. The role of EP neurones might be to supply contiguous elements with a gaze eccentricity signal required for visuo-motor processes such as the control of tracking movements.
以精确界定神经元的注视野（GF）并在两个功能不同的区域，即颞上沟内侧区（MSTd）和7a区进行比较为目的，对猕猴顶叶皮质中主要与眼位相关的神经元（眼位神经元，EP神经元）的活动进行了研究。在两只恒河猴注视视频屏幕上几个不同位置的稳定视觉目标时，记录了顶下小叶和颞上沟深层皮质中单个神经元的放电率。然后将注视野绘制为拟合平均放电率的回归曲面。在这两个区域均发现了受注视角度持续影响的细胞。注视野最常见的形式是近乎平面的表面，其最佳特征是向视野的半侧或象限倾斜的斜坡，相对于正前方（初始位置）偏心移位，中点位于注视偏心度0度至20度之间，饱和度在10度至35度之间。在少数情况下，放电率在初始位置几乎最大，在偏心度35度内降至最低。在其他情况下，注视野是峰值表面，局限于视觉空间的一个受限部分。虽然EP神经元在MST区和7a区显示出相似的注视野，但发现它们与功能不同类型的细胞混合在一起。结果表明，类似于在猴顶叶皮质几个区域中已描述的EP神经元也存在于MST区。这些细胞通过发出相对于初始位置的注视偏心度信号，在以眼眶为中心的坐标系中编码注视位置，该坐标系从正前方延伸至30 - 35度。EP神经元的作用可能是为诸如跟踪运动控制等视觉运动过程所需的相邻元件提供注视偏心度信号。
