Estimates of the contribution of single neurons to perception depend on timescale and noise correlation.
Estimates of the contribution of single neurons to perception depend on timescale and noise correlation.
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DOI：
10.1523/jneurosci.5179-08.2009
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发表时间：
2009-05-20
期刊：
影响因子：
--
通讯作者：
Newsome WT
中科院分区：
文献类型：
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作者：
Cohen MR;Newsome WT
神经元群体的灵敏度以及动物可获得的感觉信息的量受到群体中单个神经元的灵敏度以及神经元之间的噪声相关性的限制。因此，几十年来，神经生理学家设计了越来越聪明和严格的方法来测量这些关键变量。以往的研究探讨了单个中颞叶（MT）神经元的反应和方向辨别性能之间的关系，发现了一个明显的矛盾。从单个神经元的敏感性测量表明，少量的神经元可能占猴子的心理物理性能，但试验到试验的单一MT神经元活动的变化与猴子的行为只有微弱的相关性，这表明猴子的决定必须基于许多神经元的反应。我们认为，解决这个悖论在于：1）在长刺激持续时间在原来的研究中，这导致了高估的神经敏感性相对于心理物理敏感性，和2）错误的假设（因为没有数据）的噪声相关水平MT列相反的首选方向。因此，我们在方向辨别任务的反应时间版本中进行了新的生理和心理物理测量，该任务将神经测量与动物的实际决策时间相匹配。这些新的数据，考虑到我们最近的数据在MT噪声相关性，提供了一个显着改善的心理测量性能的方向辨别任务。
The sensitivity of a population of neurons, and therefore the amount of sensory information available to an animal, is limited by the sensitivity of single neurons in the population and by noise correlation between neurons. For decades, therefore, neurophysiologists have devised increasingly clever and rigorous ways to measure these critical variables. Previous studies examining the relationship between the responses of single middle temporal (MT) neurons and direction discrimination performance uncovered an apparent paradox. Sensitivity measurements from single neurons suggested that small numbers of neurons may account for a monkey’s psychophysical performance; but trial-to-trial variability in activity of single MT neurons are only weakly correlated with the monkey’s behavior, suggesting that the monkey’s decision must be based on the responses of many neurons. We suggest that the resolution to this paradox lies: 1) in the long stimulus duration employed in the original studies, which led to an overestimate of neural sensitivity relative to psychophysical sensitivity, and 2) mistaken assumptions (since no data were available) about the level of noise correlation in MT columns with opposite preferred directions. We therefore made new physiological and psychophysical measurements in a reaction time version of the direction discrimination task that matches neural measurements to the actual decision time of the animals. These new data, considered together with our recent data on noise correlation in MT, provide a substantially improved account of psychometric performance in the direction discrimination task.