Bala Avinash D S, Spitzer Matthew W, Takahashi Terry T
Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, USA.
Nature. 2003 Aug 14;424(6950):771-4. doi: 10.1038/nature01835.
The owl can discriminate changes in the location of sound sources as small as 3 degrees and can aim its head to within 2 degrees of a source. A typical neuron in its midbrain space map has a spatial receptive field that spans 40 degrees--a width that is many times the behavioural threshold. Here we have quantitatively examined the relationship between neuronal activity and perceptual acuity in the auditory space map in the barn owl midbrain. By analysing changes in firing rate resulting from small changes of stimulus azimuth, we show that most neurons can reliably signal changes in source location that are smaller than the behavioural threshold. Each source is represented in the space map by a focus of activity in a population of neurons. Displacement of the source causes the pattern of activity in this population to change. We show that this change predicts the owl's ability to detect a change in source location.
猫头鹰能够分辨出小至3度的声源位置变化，并能将其头部对准声源的2度范围内。其脑中间空间图谱中的典型神经元具有跨越40度的空间感受野——这个宽度是行为阈值的许多倍。在这里，我们定量研究了仓鸮脑中间听觉空间图谱中神经元活动与感知敏锐度之间的关系。通过分析刺激方位角的微小变化所导致的放电率变化，我们发现大多数神经元能够可靠地发出小于行为阈值的声源位置变化信号。每个声源在空间图谱中由一群神经元的活动焦点来表示。声源的位移会导致这群神经元的活动模式发生变化。我们表明，这种变化预示着猫头鹰检测声源位置变化的能力。
