Zohary E, Shadlen M N, Newsome W T
Department of Neurobiology, Stanford University School of Medicine, California 94305.
Nature. 1994 Jul 14;370(6485):140-3. doi: 10.1038/370140a0.
Single neurons can signal subtle changes in the sensory environment with surprising fidelity, often matching the perceptual sensitivity of trained psychophysical observers. This similarity poses an intriguing puzzle: why is psychophysical sensitivity not greater than that of single neurons? Pooling responses across neurons should average out noise in the activity of single cells, leading to substantially improved psychophysical performance. If, however, noise is correlated among these neurons, the beneficial effects of pooling would be diminished. To assess correlation within a pool, the responses of pairs of neurons were recorded simultaneously during repeated stimulus presentations. We report here that the observed covariation in spike count was relatively weak, the correlation coefficient averaging 0.12. A theoretical analysis revealed, however, that weak correlation can limit substantially the signalling capacity of the pool. In addition, theory suggests a relationship between neuronal responses and psychophysical decisions which may prove useful for identifying cell populations underlying specific perceptual capacities.
单个神经元能够以惊人的保真度传递感觉环境中的细微变化，常常与训练有素的心理物理学观察者的感知灵敏度相匹配。这种相似性引发了一个有趣的谜题：为什么心理物理学灵敏度不高于单个神经元的灵敏度呢？跨神经元汇总反应应该能平均掉单个细胞活动中的噪声，从而显著提高心理物理学表现。然而，如果这些神经元之间的噪声是相关的，汇总的有益效果就会减弱。为了评估一个汇总组内的相关性，在重复刺激呈现过程中同时记录了成对神经元的反应。我们在此报告，观察到的尖峰计数协变相对较弱，相关系数平均为0.12。然而，理论分析表明，弱相关性会极大地限制汇总组的信号传递能力。此外，理论提出了神经元反应与心理物理学决策之间的一种关系，这可能有助于识别特定感知能力背后的细胞群体。
