Richmond B J, Optican L M, Podell M, Spitzer H
J Neurophysiol. 1987 Jan;57(1):132-46. doi: 10.1152/jn.1987.57.1.132.
We seek a general approach to determine what stimulus features visual neurons are sensitive to and how those features are represented by the neuron's responses. Because lesions of inferior temporal (IT) cortex interfere with a monkey's ability to perform pattern discrimination tasks we studied IT neurons. Previous single-unit studies have shown that IT neurons sometimes respond more strongly to complex stimuli (brushes, hands, faces) than to simple stimuli (bars, slits, edges). However, it is not known how specific stimulus parameters are represented by responses. We studied the responses of IT neurons in alert behaving monkeys to a large set of two-dimensional black and white patterns. The stimulus set was based on 64 Walsh functions that can be used to represent any picture with a resolution of one part in eight along each of two dimensions. The responses to these stimuli spanned a continuum from inhibition to strong excitation. A statistical test showed that the spike count was determined by which Walsh stimulus was presented. Hence, these stimuli form an adequate set for testing IT neurons. The responses showed temporal modulation of the spike train that could not be represented by a change in the spike count alone. Examples of this modulation were changes in latency, changes in the duration of the response, and alternating periods of excitation and inhibition. This temporal modulation may be important in representing stimulus parameters. The next paper in this series develops a method for quantifying this temporal modulation and shows that it is dependent on the stimulus. The third paper in this series shows that this temporal modulation contains more information about stimulus parameters than is contained in the spike count alone.
我们寻求一种通用方法，以确定视觉神经元对哪些刺激特征敏感，以及这些特征如何由神经元的反应来表征。由于颞下（IT）皮质损伤会干扰猴子执行模式辨别任务的能力，所以我们对IT神经元进行了研究。先前的单单元研究表明，IT神经元有时对复杂刺激（刷子、手、脸）的反应比对简单刺激（条形、狭缝、边缘）更强烈。然而，尚不清楚特定的刺激参数是如何由反应来表征的。我们研究了清醒行为猴子中IT神经元对大量二维黑白图案的反应。刺激集基于64个沃尔什函数，这些函数可用于以二维中每维八分之一的分辨率表示任何图片。对这些刺激的反应范围从抑制到强烈兴奋。一项统计测试表明，尖峰计数由呈现的沃尔什刺激决定。因此，这些刺激构成了测试IT神经元的合适集合。反应显示出尖峰序列的时间调制，这不能仅由尖峰计数的变化来表示。这种调制的例子包括潜伏期的变化、反应持续时间的变化以及兴奋和抑制的交替期。这种时间调制在表征刺激参数方面可能很重要。本系列的下一篇论文开发了一种量化这种时间调制的方法，并表明它取决于刺激。本系列的第三篇论文表明，这种时间调制包含的关于刺激参数的信息比仅尖峰计数中包含的信息更多。
