Tolhurst D J, Movshon J A, Dean A F
Vision Res. 1983;23(8):775-85. doi: 10.1016/0042-6989(83)90200-6.
The variability of the discharge of visual cortical neurons in cats and macaque monkeys limits the reliability with which such neurons can relay signals about weak visual stimuli. In general, the variance of a neuron's firing rate is directly proportional to its mean firing rate. The probability that a neuron will fire a criterion number of impulses on a stimulus trial grows monotonically with the contrast of a sinusoidal grating stimulus. Neural probability functions prepared either by computing the probability of criterion response or by integrating receiver operating characteristics to yield the probability of correct choice in a two-alternative forced-choice situation resemble psychometric functions obtained in psychophysical and behavioral experiments on humans and animals, but are shallower in slope. The slopes of neuronal probability functions are slightly higher when they are estimated over short time periods, but even so do not equal the slopes measured psychophysically in human and monkey observers. This discrepancy in slope could be explained if the whole observer responded only when about four neurons were active together.
猫和猕猴视觉皮层神经元放电的变异性限制了这些神经元传递有关微弱视觉刺激信号的可靠性。一般来说，神经元放电率的方差与其平均放电率成正比。在刺激试验中，神经元发放标准数量冲动的概率会随着正弦光栅刺激的对比度单调增加。通过计算标准反应概率或整合接受者操作特征以得出二选一强制选择情境中正确选择概率所制备的神经概率函数，类似于在人类和动物的心理物理学及行为实验中获得的心理测量函数，但斜率更平缓。当在短时间内进行估计时，神经元概率函数的斜率会略高一些，但即便如此也不等于在人类和猴子观察者身上通过心理物理学测量得到的斜率。如果整个观察者仅在大约四个神经元同时活跃时才做出反应，那么这种斜率差异就可以得到解释。
