Molecular Neurobiology Laboratory, The Salk Institute For Biological Studies, La Jolla, California, USA.
Nat Neurosci. 2013 Aug;16(8):1060-7. doi: 10.1038/nn.3454. Epub 2013 Jul 7.
The primary somatosensory cortex (S1) contains a complete body map that mirrors the subcortical maps developed by peripheral sensory input projecting to the sensory hindbrain, the thalamus and then S1. Peripheral changes during development alter these maps through 'bottom-up' plasticity. Unknown is how S1 size influences map organization and whether an altered S1 map feeds back to affect subcortical maps. We show that the size of S1 in mice is significantly reduced by cortex-specific deletion of Pax6, resulting in a reduced body map and loss of body representations by an exclusion of later-differentiating sensory thalamocortical input. An initially normal sensory thalamus was repatterned to match the aberrant S1 map by apoptotic deletion of thalamic neurons representing body parts with axons excluded from S1. Deleted representations were rescued by altering competition between thalamocortical axons using sensory deprivation or increasing the size of S1. Thus, S1 size determined the resolution and completeness of body maps and engaged 'top-down' plasticity that repatterned the sensory thalamus to match S1.
初级躯体感觉皮层（S1）包含一个完整的身体图，反映了由投射到感觉后脑、丘脑然后 S1 的外周感觉输入所发展的皮质下图。发育过程中的外周变化通过“自上而下”的可塑性改变这些图。尚不清楚 S1 的大小如何影响图的组织，以及改变的 S1 图是否会反馈影响皮质下图。我们表明，通过 Pax6 的皮层特异性缺失，小鼠 S1 的大小显著减小，导致身体图减小，并且由于来自 S1 的轴突被排除在外，身体代表丧失。最初正常的感觉丘脑通过代表来自 S1 的轴突被排除在外的身体部分的丘脑神经元的凋亡性缺失，被重新模式化为与异常 S1 图匹配。通过使用感觉剥夺或增加 S1 的大小来改变丘脑皮质轴突之间的竞争，删除的表示被挽救。因此，S1 的大小决定了身体图的分辨率和完整性，并参与了重新模式化感觉丘脑以匹配 S1 的“自上而下”可塑性。
