Scott Brian H, Malone Brian J, Semple Malcolm N
Center for Neural Science, New York University, New York, New York 10003, USA.
J Neurosci. 2007 Jun 13;27(24):6489-99. doi: 10.1523/JNEUROSCI.0016-07.2007.
Primary auditory cortex plays a crucial role in spatially directed behavior, but little is known about the effect of behavioral state on the neural representation of spatial cues. Macaques were trained to discriminate binaural cues to sound localization, eventually allowing measurement of thresholds comparable to human hearing. During behavior and passive listening, single units in low-frequency auditory cortex showed robust and consistent tuning to interaural phase difference (IPD). In most neurons, behavior exerted an effect on peak discharge rate (58% increased, 13% decreased), but this was not accompanied by a detectable shift in the best IPD of any cell. Neurometric analysis revealed a difference in discriminability between the behaving and passive condition in half of the sample (52%), but steepening of the neurometric function (29%) was only slightly more common than flattening (23%). This suggests that performance of a discrimination task does not necessarily confer an advantage in understanding the representation of the spatial cue in primary auditory cortex but nevertheless revealed some physiological effects. These results suggest that responses observed during passive listening provide a valid representation of neuronal response properties in core auditory cortex.
初级听觉皮层在空间定向行为中起着至关重要的作用，但关于行为状态对空间线索神经表征的影响却知之甚少。猕猴经过训练以辨别用于声音定位的双耳线索，最终得以测量出与人类听力相当的阈值。在行为过程和被动聆听期间，低频听觉皮层中的单个神经元对双耳相位差（IPD）表现出强大且一致的调谐。在大多数神经元中，行为对峰值放电率产生了影响（58% 增加，13% 降低），但这并未伴随着任何细胞的最佳 IPD 出现可检测到的偏移。神经测量分析显示，在一半的样本（52%）中，行为状态与被动状态之间的可辨别性存在差异，但神经测量函数变陡（29%）仅比变平（23%）略为常见。这表明执行辨别任务并不一定会在理解初级听觉皮层中空间线索的表征方面带来优势，但仍揭示了一些生理效应。这些结果表明，被动聆听期间观察到的反应为核心听觉皮层中神经元反应特性提供了有效的表征。
