VISUOMOTOR FIELDS OF THE SUPERIOR COLLICULUS - A QUANTITATIVE MODEL
VISUOMOTOR FIELDS OF THE SUPERIOR COLLICULUS - A QUANTITATIVE MODEL
复制标题
DOI：
10.1016/0042-6989(86)90144-6
复制
发表时间：
1986-01-01
期刊：
影响因子：
1.8
通讯作者：
EGGERMONT, JJ
中科院分区：
文献类型：
--
作者：
OTTES, FP;VANGISBERGEN, JAM;EGGERMONT, JJ
对猴子的电生理学和电刺激研究已经揭示了视网膜表面和扫视的度量都在上级丘中地形地表示。这种感觉和运动空间到丘的映射是不均匀的，因为中央区域在视觉和运动映射中都被过度表示。单个单位的研究表明，丘神经元的视觉感受野通常相当大，其特征在于偏斜（不对称）的敏感性曲线。分析由McIllem [J. Neurophysiol. 38，219-230（1975）]的研究表明，这种偏度特性主要反映了传入映射中固有的空间失真。在本文中，我们描述了一个定量模型，该模型基于丘中的对数映射函数与高斯连接函数相结合，可以解释丘感受野的范围和形状。更深层的丘神经元在与它们在丘地图中的位置相关的有限幅度和方向范围内具有与运动相关的扫视活动爆发。这些运动场，如视觉感受场，可能相当广泛，通常具有偏斜的轮廓。在我们的模型中，定义了一个传出映射函数，该函数将招募的细胞群体的位点与随后的眼跳的度量相关联。该函数的参数被认为与传入映射函数相同，根据Robinson的[Vision Res. 12，1795-1808（1972）]电刺激数据进行估计。基于人口活动分布类似于二维高斯函数的假设，运动场的形状和大小可以用2或3个自由参数来描述。从一个小样本的丘视神经元记录的电生理数据被用来说明的程序，我们设计，使我们的模型的应用程序的实验数据。当映射函数略微各向异性时，获得最佳拟合。讨论中提出了如何改进和扩展该模型的建议。
Electrophysiological and electrical stimulation studies in the monkey have disclosed that both the retinal surface and the metrics of saccades are topographically represented in the superior colliculus. This mapping of sensory and motor space onto the colliculus is nonhomogeneous in that the central region is over-represented in both the visual and the motor map. Single unit studies have revealed that visual receptive fields of collicular neurons are typically quite large and are characterized by a skewed (asymmetrical) sensitivity profile. Analyses by McIlwain [J. Neurophysiol. 38, 219-230 (1975)] in the cat have suggested that this skewness property reflects mainly the spatial distortion inherent in the afferent mapping. In this paper we describe a quantitative model, based on a logarithmic mapping function combined with a Gaussian connectivity function in the colliculus, which can account for the extent and the shape of collicular receptive fields. Collicular neurons in the deeper layers have movement-related bursts of activity for saccades in a limited amplitude and direction range related to their location in the collicular map. These movement fields, like visual receptive fields, may be quite extensive and typically have a skewed profile. In our model, an efferent-mapping function is defined, which relates the locus of a population of recruited cells to the metrics of the ensuing saccade. The parameters of this function, which was taken to be identical with the afferent mapping function, were estimated from Robinson''s [Vision Res. 12, 1795-1808 (1972)] electrical stimulation data. Based on the assumption that the population-activity profile resembles a two-dimensional Gaussian function, the shape and the size of movement fields can then be described with just 2 or 3 free parameters. Electrophysiological data recorded from a small sample of collicular visuomotor neurons were used to illustrate the procedure, which we designed to enable application of our model to the experimental data. The best fit was obtained when the mapping function was slightly anisotropic. Suggestions on how the model could be improved and extended are offered in the Discussion.