SPEED AND DIRECTION SELECTIVITY OF MACAQUE MIDDLE TEMPORAL NEURONS
SPEED AND DIRECTION SELECTIVITY OF MACAQUE MIDDLE TEMPORAL NEURONS
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DOI：
10.1152/jn.1993.69.1.19
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发表时间：
1993-01-01
影响因子：
2.5
通讯作者：
ORBAN, GA
中科院分区：
文献类型：
--
作者：
LAGAE, L;RAIGUEL, S;ORBAN, GA
1.我们定量地测试了147个中颞叶（MT）细胞对以1,000倍范围（0.5-512度/秒）的不同速度移动的亮条和暗条的反应。我们从运动方向相反的速度响应（SR）曲线中推导出以下参数。速度选择性的特征在于最大响应。最佳速度、上限截止速度、对慢速运动的响应以及调谐宽度。方向选择性的特征在于方向指数（DI）的平均速度产生显着的反应（MDI）和方向指数在最佳速度（PDI）。有一个很好的相关性之间的速度特性为光明和黑暗的酒吧。这些相关性强于方向指数之间的相关性。最强的相关性得到了最大响应和上限。SR曲线分为三组：低通（25%），调谐（43%）和宽带（28%），留下4%未分类。在大多数（75%）MT细胞中，亮条和暗条的速度选择性类型之间存在一致性。细胞被分类为调谐（33%），低通（22%），宽带（19%）和混合（22%），剩下4%未分类。除了速度特征的差异外，这些群体在反应水平、方向选择性和偏好方向的分布上也存在差异。对于调谐细胞，有一个非常紧密的相关性的大多数速度特性的光和暗酒吧。在大多数神经元中，方向选择性依赖于刺激速度，产生调谐的平均速度-DI曲线。速度特性、速度选择性类型的比例和方向选择性指数对层流位置的依赖性很小。速度特性和方向选择性指标不依赖于偏心。然而，速度选择性类型的比例随着偏心率而显著变化：低通细胞在中央凹占主导地位，调谐细胞在旁轴，宽带细胞在周边。也有小的偏心率的影响范围内的最佳速度调谐细胞和速度的方向选择性降低在低速范围内。
1. We tested quantitativelv the responses of 147 middle temporal (MT) cells to light and dark bars moving at different speeds ranging over a 1,000-fold range (0.5-512 deg/s).2. We derived the following quantities from the speed-response (SR) curves obtained for opposite directions of motion. Speed selectivity was characterized by the maximum response. optimum speed, upper cutoff speed, response to slow movement, and tuning width. Direction selectivity was characterized by the direction index (DI) averaged over speeds yielding significant responses (MDI) and by the direction index at optimal speed (PDI).3. There was an excellent correlation between speed characteristics for light and dark bars. These correlations were stronger than the correlations between direction indexes. The strongest correlations were obtained for maximum response and upper cutoff.4. SR curves were classified into three groups: low pass (25%), tuned (43%), and broadband (28%), leaving 4% unclassified.5. In the majority (75%) of MT cells, there was an agreement between the typology of speed selectivity for light and dark bars. Cells were classified as tuned (33%), low pass (22%), broadband (19%), and mixed (22%), leaving 4% unclassified. In addition to differences in speed characteristics, these groups also differed in response level, direction selectivity, and distribution of preferred directions.6. For tuned cells, there was a very tight correlation of most speed characteristics for light and dark bars.7. Direction selectivity depended on stimulus speed in most neurons, yielding a tuned average speed-DI curve.8. Speed characteristics, proportions of speed selectivity types, and direction selectivity indexes showed little dependence on laminar position.9. Speed characteristics and direction selectivity indexes were not dependent on eccentricity. Proportion of speed selectivity types however, changed dramatically with eccentricity: low-pass cells dominated foveally, tuned cells parafoveally, and broadband cells peripherally.10. There were also small eccentricity effects on the range of optimal speeds shown by tuned cells and on the speed at which direction selectivity decreases in the slow speed range.