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首页> 外文期刊>Journal of Computational Neuroscience >Representation of motion onset and offset in an augmented Barlow-Levick model of motion detection
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Representation of motion onset and offset in an augmented Barlow-Levick model of motion detection

机译：运动检测的增强Barlow-Levick模型中运动开始和偏移的表示

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摘要

Kinetic occlusion produces discontinuities in the optic flow field, whose perception requires the detection of an unexpected onset or offset of other wise predictably moving or stationary contrast patches. Many cells in primate visual cortex are directionally selective for moving contrasts, and recent reports sug gest that this selectivity arises through the inhibition of contrast signals moving in the cells' null direction, as in the rabbit retina. This nulling inhibition circuit (Barlow-Levick) is here extended to also detect motion onsets and offsets. The selectivity of extended circuit units, measured as a peak evidence accumulation re sponse to motion onset/offset compared to the peak response to constant motion, is analyzed as a function of stimulus speed. Model onset cells are quiet during constant motion, but model offset cells activate during constant motion at slow speeds. Consequently, model offset cell speed tuning is biased towards higher speeds than onset cell tuning, similarly to the speed tuning of cells in the middle temporal area when exposed to speed ramps. Given a population of neurons with different preferred speeds, this asymmetry addresses a behavioral paradox-why human subjects in a sim ple reaction time task respond more slowly to motion offsets than onsets for low speeds, even though monkey neuron firing rates react more quickly to the offset of a preferred stimulus than to its onset.
机译：动力学闭塞会在光流场中产生不连续性，其感知需要检测其他可预测地移动或固定的对比斑块的意外发作或偏移。灵长类动物视皮层中的许多细胞对移动的造影剂具有方向选择性，而最近的报道表明，这种选择性是通过抑制沿空白方向移动的造影剂信号而产生的，就像在兔子视网膜中一样。该无效抑制电路（Barlow-Levick）在此扩展为还可以检测运动的开始和偏移。扩展电路单元的选择性（作为对运动开始/偏移的峰值证据积累相对于对恒定运动的峰值响应的响应）进行了分析，并作为刺激速度的函数进行了分析。在恒定运动中，模型起始单元是安静的，但是在恒定运动中，模型偏移单元会以低速激活。因此，模型偏移像元速度调整倾向于比初始像元调整更高的速度，这与中速时区中的像元暴露于速度斜坡时的速度调整类似。给定一群具有不同首选速度的神经元，这种不对称解决了行为悖论。为什么在简单的反应时间任务中，人类对象对运动偏移的反应比低速反应的起效要慢，即使猴子神经元的放电速度对起搏反应的反应更快。首选刺激的抵消作用而不是其开始作用。

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