Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Neurosci. 2012 Aug 1;32(31):10470-8. doi: 10.1523/JNEUROSCI.0047-12.2012.
The physical arrangement of receptive fields (RFs) within neural structures is important for local computations. Nonuniform distribution of tuning within populations of neurons can influence emergent tuning properties, causing bias in local processing. This issue was studied in the auditory system of barn owls. The owl's external nucleus of the inferior colliculus (ICx) contains a map of auditory space in which the frontal region is overrepresented. We measured spatiotemporal RFs of ICx neurons using spatial white noise. We found a population-wide bias in surround suppression such that suppression from frontal space was stronger. This asymmetry increased with laterality in spatial tuning. The bias could be explained by a model of lateral inhibition based on the overrepresentation of frontal space observed in ICx. The model predicted trends in surround suppression across ICx that matched the data. Thus, the uneven distribution of spatial tuning within the map could explain the topography of time-dependent tuning properties. This mechanism may have significant implications for the analysis of natural scenes by sensory systems.
感受野（RFs）在神经结构内的物理排列对于局部计算很重要。神经元群体中调谐的非均匀分布会影响涌现的调谐特性，导致局部处理产生偏差。这个问题在仓鸮的听觉系统中进行了研究。仓鸮的下丘外侧核（ICx）包含听觉空间的图谱，其中前部区域被过度表示。我们使用空间白噪声测量了 ICx 神经元的时空 RFs。我们发现，周围抑制存在普遍的偏差，即来自前部空间的抑制更强。这种不对称性随着空间调谐的偏侧性而增加。基于在 ICx 中观察到的前部空间的过度表示，可以用基于侧抑制的模型来解释这种偏差。该模型预测了在 ICx 中跨越时间调谐特性的周围抑制的趋势，与数据相匹配。因此，图谱内空间调谐的不均匀分布可以解释时变调谐特性的地形。这种机制可能对感觉系统对自然场景的分析具有重要意义。
