de Villers-Sidani Etienne, Simpson Kimberly L, Lu Y-F, Lin Rick C S, Merzenich Michael M
W.M. Keck Center for Integrative Neuroscience, Coleman Laboratory, Department of Otolaryngology, University of California, San Francisco, 513 Parnassus Avenue, Room HSE-808, Box 0732, San Francisco, California 94143, USA.
Nat Neurosci. 2008 Aug;11(8):957-65. doi: 10.1038/nn.2144. Epub 2008 Jul 6.
During early brain development and through 'adult' experience-dependent plasticity, neural circuits are shaped to represent the external world with high fidelity. When raised in a quiet environment, the rat primary auditory cortex (A1) has a well-defined 'critical period', lasting several days, for its representation of sound frequency. The addition of environmental noise extends the critical period duration as a variable function of noise level. It remains unclear whether critical period closure should be regarded as a unified, externally gated event that applies for all of A1 or if it is controlled by progressive, local, activity-driven changes in this cortical area. We found that rearing rats in the presence of a spectrally limited noise band resulted in the closure of the critical period for A1 sectors representing the noise-free spectral bands, whereas the critical period appeared to remain open in noise-exposed sectors, where the cortex was still functionally and physically immature.
在大脑早期发育过程中以及通过“成年”期依赖经验的可塑性，神经回路被塑造以高保真度表征外部世界。当在安静环境中饲养时，大鼠初级听觉皮层（A1）对声音频率的表征有一个明确的“关键期”，持续数天。添加环境噪声会将关键期持续时间延长，这是噪声水平的可变函数。目前尚不清楚关键期的关闭应被视为适用于整个A1的统一的、外部门控事件，还是由该皮层区域中渐进的、局部的、活动驱动的变化所控制。我们发现，在存在频谱受限噪声带的情况下饲养大鼠，会导致代表无噪声频谱带的A1区域的关键期关闭，而在暴露于噪声的区域，关键期似乎仍然开放，在这些区域皮层在功能和物理上仍未成熟。
