Smith A T
Department of Psychology, Royal Holloway College, University of London, Egham, Surrey, England.
Vis Neurosci. 1996 Sep-Oct;13(5):873-84. doi: 10.1017/s0952523800009123.
A model of contrast discrimination performance in human observers is developed and then extended to cover effects on performance of anticholinergic drugs. It is shown that it is necessary to assume that neural noise increases at high spatial frequencies in order to provide a satisfactory model of variations in discrimination performance with spatial frequency. The model results are compared with the results of empirical studies in which the effects of the muscarinic antagonist scopolamine (hyoscine) on contrast discrimination performance in human observers are examined. The purpose of the pharmacological work is to test the hypothesis that the differential contrast gain found psychophysically at different spatial frequencies might reflect differential facilitation by extrinsic cholinergic neurons. Contrast discrimination and contrast increment detection are found to be impaired by scopolamine in a manner that depends on both spatial frequency and base contrast. By comparing the empirical data with the predictions of the model, it is concluded that contrast constancy may reflect differential cholinergic modulation.
开发了一种人类观察者对比度辨别性能的模型，然后将其扩展以涵盖抗胆碱能药物对性能的影响。结果表明，有必要假设神经噪声在高空间频率下会增加，以便提供一个令人满意的关于辨别性能随空间频率变化的模型。将模型结果与实证研究结果进行了比较，在这些实证研究中，研究了毒蕈碱拮抗剂东莨菪碱对人类观察者对比度辨别性能的影响。药理学研究的目的是检验这样一个假设，即在不同空间频率下通过心理物理学发现的差异对比度增益可能反映了外在胆碱能神经元的差异促进作用。发现东莨菪碱会以一种既取决于空间频率又取决于基础对比度的方式损害对比度辨别和对比度增量检测。通过将实证数据与模型预测进行比较，得出结论：对比度恒常性可能反映了差异胆碱能调制。
