UCL Ear Institute, London, United Kingdom.
J Neurophysiol. 2012 Oct;108(7):1856-68. doi: 10.1152/jn.00652.2011. Epub 2012 Jul 5.
Many neurons adapt their spike output to accommodate the prevailing sensory environment. Although such adaptation is thought to improve coding of relevant stimulus features, the relationship between adaptation at the neural and behavioral levels remains to be established. Here we describe improved discrimination performance for an auditory spatial cue (interaural time differences, ITDs) following adaptation to stimulus statistics. Physiological recordings in the midbrain of anesthetized guinea pigs and measurement of discrimination performance in humans both demonstrate improved coding of the most prevalent ITDs in a distribution, but with highest accuracy maintained for ITDs corresponding to frontal locations, suggesting the existence of a fovea for auditory space. A biologically plausible model accounting for the physiological data suggests that neural tuning is stabilized by inhibition to maintain high discriminability for frontal locations. The data support the notion that adaptive coding in the midbrain is a key element of behaviorally efficient sound localization in dynamic acoustic environments.
许多神经元会调整其尖峰输出以适应当前的感官环境。尽管这种适应被认为可以改善相关刺激特征的编码，但神经和行为水平之间的适应关系仍有待确定。在这里，我们描述了在适应刺激统计数据后，对听觉空间线索（耳间时间差，ITD）的辨别性能的提高。麻醉豚鼠的中脑记录和人类的辨别性能测量都表明，在分布中对最常见的 ITD 进行了更好的编码，但对对应于额位的 ITD 保持了最高的准确性，这表明听觉空间存在一个中央凹。一个能够解释生理数据的生物上合理的模型表明，通过抑制来稳定神经调谐，以保持对额位的高辨别能力。这些数据支持这样一种观点，即中脑的适应性编码是在动态声环境中进行行为高效声音定位的关键要素。
