Radnikow Gabriele, Feldmeyer Dirk
Research Centre Jülich, Institute of Neuroscience and Medicine, INM-10, Jülich, Germany.
Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany.
Front Neuroanat. 2018 Jan 30;12:1. doi: 10.3389/fnana.2018.00001. eCollection 2018.
From an anatomical point of view the neocortex is subdivided into up to six layers depending on the cortical area. This subdivision has been described already by Meynert and Brodmann in the late 19/early 20. century and is mainly based on cytoarchitectonic features such as the size and location of the pyramidal cell bodies. Hence, cortical lamination is originally an anatomical concept based on the distribution of excitatory neuron. However, it has become apparent in recent years that apart from the layer-specific differences in morphological features, many functional properties of neurons are also dependent on cortical layer or cell type. Such functional differences include changes in neuronal excitability and synaptic activity by neuromodulatory transmitters. Many of these neuromodulators are released from axonal afferents from subcortical brain regions while others are released intrinsically. In this review we aim to describe layer- and cell-type specific differences in the effects of neuromodulator receptors in excitatory neurons in layers 2-6 of different cortical areas. We will focus on the neuromodulator systems using adenosine, acetylcholine, dopamine, and orexin/hypocretin as examples because these neuromodulator systems show important differences in receptor type and distribution, mode of release and functional mechanisms and effects. We try to summarize how layer- and cell type-specific neuromodulation may affect synaptic signaling in cortical microcircuits.
从解剖学角度来看，根据皮质区域的不同，新皮质可细分为多达六层。这种细分在19世纪末/20世纪初就已由迈内特和布罗德曼描述过，主要基于细胞结构特征，如锥体细胞体的大小和位置。因此，皮质分层最初是一个基于兴奋性神经元分布的解剖学概念。然而，近年来已经很明显，除了形态特征上的层特异性差异外，神经元的许多功能特性也取决于皮质层或细胞类型。这些功能差异包括神经调质递质对神经元兴奋性和突触活动的改变。许多这些神经调质是从皮质下脑区的轴突传入释放的，而其他的则是内在释放的。在这篇综述中，我们旨在描述神经调质受体对不同皮质区域第2 - 6层兴奋性神经元作用的层特异性和细胞类型特异性差异。我们将以使用腺苷、乙酰胆碱、多巴胺和食欲素/下丘脑分泌素的神经调质系统为例，因为这些神经调质系统在受体类型和分布、释放方式以及功能机制和作用方面表现出重要差异。我们试图总结层特异性和细胞类型特异性神经调节如何影响皮质微回路中的突触信号传递。
