Non-canonical role for Lpar1-EGFP subplate neurons in early postnatal somatosensory cortex
Non-canonical role for Lpar1-EGFP subplate neurons in early postnatal somatosensory cortex
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DOI：
10.1101/2020.05.12.088450
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发表时间：
2020-05
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通讯作者：
Filippo Ghezzi;André Marques-Smith;Paul G. Anastasiades;D. Lyngholm;C. Vagnoni;Alexandra Rowett;A. Hoerder-Suabedissen;Y. Nakagawa;Z. Molnár;S. Butt
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作者：
Filippo Ghezzi;André Marques-Smith;Paul G. Anastasiades;D. Lyngholm;C. Vagnoni;Alexandra Rowett;A. Hoerder-Suabedissen;Y. Nakagawa;Z. Molnár;S. Butt
亚板神经元（subplate neurons，SPNs）是一种短暂的神经元，在新生的感觉加工过程中起着关键作用，将丘脑的信息传递到发育中的大脑皮层。然而，人们对这个群体中的异质性与紧急功能的关系知之甚少。为了解决这个问题，我们采用光学和电生理技术，研究突触连接的SPNs定义的Lpar1-EGFP转基因的表达，通过出生后第一周在小鼠的初级须体感皮层（S1BF）。我们的数据确定Lpar1-EGFP SPN代表两种形态学亚型：（1）短暂的梭形SPN，轴突主要局限于亚板区;（2）锥体SPN，轴突侧支穿过上覆皮质延伸穿过边缘区。用激光扫描光刺激笼状谷氨酸来确定对这两种SPN亚型的柱状谷氨酸能和GABA能输入。这些实验表明，前者从更浅的皮质层接受经椎板输入，直到胡须桶的出现（~出生后（P）5）。与此相反，锥体SPN在早期只接受来自相邻亚板网络的局部输入，但在以后的年龄可以获得来自覆盖皮层的各种输入。丘脑腹后核的联合电刺激和丘脑皮层切片制备中丘脑传入神经的光遗传学激活揭示了Lpar1-EGFP SPN在出生后早期发育期间仅接受稀疏的丘脑神经支配。两者合计，这些数据揭示了两个组成部分的出生后网络，解释稀疏丘脑输入，以指导新生儿躯体感觉皮层的新兴柱状结构。
Subplate neurons (SPNs) are a transient neuronal population shown to play a key role in nascent sensory processing relaying thalamic information to the developing cerebral cortex. However there is little understanding of how heterogeneity within this population relates to emergent function. To address this question we employed optical and electrophysiological technologies to investigate the synaptic connectivity of SPNs defined by expression of the Lpar1-EGFP transgene through the first postnatal week in primary whisker somatosensory cortex (S1BF) in mouse. Our data identify that the Lpar1-EGFP SPNs represent two morphological subtypes: (1) transient, fusiform SPNs with axons largely restricted to the subplate zone; (2) pyramidal SPNs with axon collaterals that traverse the overlying cortex to extend through the marginal zone. Laser scanning photostimulation of caged glutamate was used to determine columnar glutamatergic and GABAergic input onto both of these SPN subtypes. These experiments revealed that the former receive translaminar input from more superficial cortical layers up until the emergence of the whisker barrels (~postnatal (P)5). In contrast, pyramidal SPNs only receive local input from the adjacent subplate network at early ages but then at later ages can acquire varied input from the overlying cortex. Combined electrical stimulation of the ventral posterior nucleus of the thalamus and optogenetic activation of thalamic afferents in thalamocortical slice preparations revealed that Lpar1-EGFP SPNs only receive sparse thalamic innervation during early postnatal development. Taken together, these data reveal two components of the postnatal network that interpret sparse thalamic input to direct the emergent columnar structure of neonatal somatosensory cortex.