Hage Steffen R, Ehret Günter
Department of Neurobiology, University of Ulm, D-89069 Ulm, Germany.
Eur J Neurosci. 2003 Oct;18(8):2301-12. doi: 10.1046/j.1460-9568.2003.02945.x.
In auditory maps of the primary auditory cortex, neural response properties are arranged in a systematic way over the cortical surface. As in the visual system, such maps may play a critical role in the representation of sounds for perception and cognition. By recording from single neurons in the central nucleus of the inferior colliculus (ICC) of the mouse, we present the first evidence for spatial organizations of parameters of frequency sweeps (sweep speed, upward/downward sweep direction) and of whole-field tone response patterns together with a map of frequency tuning curve shape. The maps of sweep speed, tone response patterns and tuning curve shape are concentrically arranged on frequency band laminae of the ICC with the representation of slow speeds, build up response types and sharp tuning mainly in the centre of a lamina, and all (including high) speeds, phasic response types and broad tuning mainly in the periphery. Representation of sweep direction shows preferences for upward sweeps medially and laterally and downward sweeps mainly centrally in the ICC (either striped or concentric map). These maps are compatible with the idea of a gradient of decreasing inhibition from the centre to the periphery of the ICC and by gradients of intrinsic neuronal properties (onset or sustained responding). The maps in the inferior colliculus compare favourably with corresponding maps in the primary auditory cortex, and we show how the maps of sweep speed and direction selectivity of the primary auditory cortex could be derived from the here-found maps of the inferior colliculus.
在初级听觉皮层的听觉图谱中，神经反应特性在皮层表面以系统的方式排列。与视觉系统一样，此类图谱可能在声音感知和认知的表征中发挥关键作用。通过记录小鼠下丘中央核（ICC）中的单个神经元，我们首次证明了频率扫描参数（扫描速度、向上/向下扫描方向）和全场音调反应模式的空间组织，以及频率调谐曲线形状图谱。扫描速度、音调反应模式和调谐曲线形状的图谱同心排列在ICC的频带层上，低速、累积反应类型和尖锐调谐主要在层的中心表示，而所有速度（包括高速）、相位反应类型和宽调谐主要在外围表示。扫描方向的表示显示，在ICC中，内侧和外侧偏好向上扫描，而主要在中央偏好向下扫描（呈条纹状或同心图谱）。这些图谱与ICC从中心到外围抑制作用递减的梯度以及内在神经元特性（起始或持续反应）的梯度的观点相一致。下丘中的图谱与初级听觉皮层中的相应图谱相比具有优势，并且我们展示了初级听觉皮层的扫描速度和方向选择性图谱如何从这里发现的下丘图谱推导出来。
