Department of Biology, Institute for Systems Research, and Program in Neuroscience and Cognitive Science, University of Maryland, College Park, Maryland 20742, USA.
J Neurosci. 2012 Feb 1;32(5):1589-601. doi: 10.1523/JNEUROSCI.4748-11.2012.
Subplate neurons (SPNs) are a population of neurons in the mammalian cerebral cortex that exist predominantly in the prenatal and early postnatal period. Loss of SPNs prevents the functional maturation of the cerebral cortex. SPNs receive subcortical input from the thalamus and relay this information to the developing cortical plate and thereby can influence cortical activity in a feedforward manner. Little is known about potential feedback projections from the cortical plate to SPNs. Thus, we investigated the spatial distribution of intracortical synaptic inputs to SPNs in vitro in mouse auditory cortex by photostimulation. We find that SPNs fell into two broad classes based on their distinct spatial patterns of synaptic inputs. The first class of SPNs receives inputs from only deep cortical layers, while the second class of SPNs receives inputs from deep as well as superficial layers including layer 4. We find that superficial cortical inputs to SPNs emerge in the second postnatal week and that SPNs that receive superficial cortical input are located more superficially than those that do not. Our data thus suggest that distinct circuits are present in the subplate and that, while SPNs participate in an early feedforward circuit, they are also involved in a feedback circuit at older ages. Together, our results show that SPNs are tightly integrated into the developing thalamocortical and intracortical circuit. The feedback projections from the cortical plate might enable SPNs to amplify thalamic inputs to SPNs.
基板神经元（SPNs）是哺乳动物大脑皮层中的一种神经元群体，主要存在于产前和出生后的早期阶段。SPNs 的缺失会阻止大脑皮层的功能成熟。SPNs 从丘脑接收皮质下输入，并将此信息中继到发育中的皮质板，从而可以以前馈方式影响皮质活动。关于皮质板向 SPNs 的潜在反馈投射知之甚少。因此，我们通过光刺激研究了体外小鼠听觉皮层中 SPNs 的皮质内突触输入的空间分布。我们发现，根据其独特的突触输入空间模式，SPNs 可分为两类。第一类 SPN 仅接收来自深层皮质层的输入，而第二类 SPN 接收来自深层和浅层的输入，包括第 4 层。我们发现，浅层皮质对 SPN 的输入出现在出生后的第二周，并且接收浅层皮质输入的 SPN 比不接收的 SPN 位于更深的位置。因此，我们的数据表明基板中存在不同的回路，尽管 SPN 参与早期的前馈回路，但它们在老年时也参与反馈回路。总的来说，我们的研究结果表明 SPN 与发育中的丘脑皮质和皮质内回路紧密集成。来自皮质板的反馈投射可能使 SPN 能够放大对 SPN 的丘脑输入。
