Crocker-Buque Alex, Brown Sarah M, Kind Peter C, Isaac John T R, Daw Michael I
Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
Developmental Synaptic Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA Current address: Lilly UK, Erl Wood Manor, Windlesham, UK.
Cereb Cortex. 2015 Aug;25(8):2255-66. doi: 10.1093/cercor/bhu031. Epub 2014 Mar 7.
The main input to primary sensory cortex is via thalamocortical (TC) axons that form the greatest number of synapses in layer 4, but also synapse onto neurons in layer 6. The development of the TC input to layer 4 has been widely studied, but less is known about the development of the layer 6 input. Here, we show that, in neonates, the input to layer 6 is as strong as that to layer 4. Throughout the first postnatal week, there is an experience-dependent strengthening specific to layer 4, which correlates with the ability of synapses in layer 4, but not in layer 6, to undergo long-term potentiation (LTP). This strengthening consists of an increase in axon branching and the divergence of connectivity in layer 4 without a change in the strength of individual connections. We propose that experience-driven LTP stabilizes transient TC synapses in layer 4 to increase strength and divergence specifically in layer 4 over layer 6.
初级感觉皮层的主要输入是通过丘脑皮质（TC）轴突，这些轴突在第4层形成了数量最多的突触，但也与第6层的神经元形成突触。对第4层TC输入的发育已经进行了广泛研究，但对第6层输入的发育了解较少。在这里，我们表明，在新生儿中，第6层的输入与第4层的输入一样强。在出生后的第一周内，存在一种特定于第4层的依赖经验的增强，这与第4层而非第6层突触进行长时程增强（LTP）的能力相关。这种增强包括轴突分支增加以及第4层连接性的发散，而单个连接的强度没有变化。我们提出，经验驱动的LTP稳定了第4层中的短暂TC突触，以特异性地增加第4层相对于第6层的强度和发散。
