Center for Neurogenetics, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States.
Front Neural Circuits. 2022 Apr 7;16:866999. doi: 10.3389/fncir.2022.866999. eCollection 2022.
Sensory information is transduced into electrical signals in the periphery by specialized sensory organs, which relay this information to the thalamus and subsequently to cortical primary sensory areas. In the cortex, microcircuits constituted by interconnected pyramidal cells and inhibitory interneurons, distributed throughout the cortical column, form the basic processing units of sensory information underlying sensation. In the mouse, these circuits mature shortly after birth. In the first postnatal week cortical activity is characterized by highly synchronized spontaneous activity. While by the second postnatal week, spontaneous activity desynchronizes and sensory influx increases drastically upon eye opening, as well as with the onset of hearing and active whisking. This influx of sensory stimuli is fundamental for the maturation of functional properties and connectivity in neurons allocated to sensory cortices. In the subsequent developmental period, spanning the first five postnatal weeks, sensory circuits are malleable in response to sensory stimulation in the so-called critical periods. During these critical periods, which vary in timing and duration across sensory areas, perturbations in sensory experience can alter cortical connectivity, leading to long-lasting modifications in sensory processing. The recent advent of intersectional genetics, calcium imaging and single cell transcriptomics has aided the identification of circuit components in emergent networks. Multiple studies in recent years have sought a better understanding of how genetically-defined neuronal subtypes regulate circuit plasticity and maturation during development. In this review, we discuss the current literature focused on postnatal development and critical periods in the primary auditory (A1), visual (V1), and somatosensory (S1) cortices. We compare the developmental trajectory among the three sensory areas with a particular emphasis on interneuron function and the role of inhibitory circuits in cortical development and function.
感觉信息由专门的感觉器官在外周转化为电信号，这些信号中继到丘脑，然后再到皮质初级感觉区。在皮质中，由相互连接的锥体细胞和抑制性中间神经元构成的微电路，分布在整个皮质柱中，构成了感觉信息的基本处理单元，这些信息是感觉的基础。在小鼠中，这些回路在出生后不久就成熟了。在出生后的第一周，皮质活动的特征是高度同步的自发性活动。而到了第二周，自发性活动去同步化，并且随着眼睛睁开、听觉和主动胡须运动的开始，感觉传入急剧增加。这种感觉刺激的传入对于分配给感觉皮质的神经元的功能特性和连接的成熟是至关重要的。在随后的发育时期，跨越出生后的前五个星期，感觉回路在所谓的关键期对感觉刺激具有可塑性。在这些关键期内，不同的感觉区域有不同的时间和持续时间，感觉经验的干扰会改变皮质连接，导致感觉处理的长期改变。近年来，交叉遗传、钙成像和单细胞转录组学的出现，有助于识别新兴网络中的回路成分。近年来的多项研究试图更好地理解遗传定义的神经元亚型如何在发育过程中调节回路可塑性和成熟。在这篇综述中，我们讨论了目前关于初级听觉（A1）、视觉（V1）和体感（S1）皮质的出生后发育和关键期的文献。我们比较了三个感觉区的发育轨迹，特别强调了中间神经元功能以及抑制性回路在皮质发育和功能中的作用。
