Vaughn Mitchell J, Haas Julie S
Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States.
Front Cell Neurosci. 2022 Jun 9;16:910015. doi: 10.3389/fncel.2022.910015. eCollection 2022.
Electrical synapses are the neurophysiological product of gap junctional pores between neurons that allow bidirectional flow of current between neurons. They are expressed throughout the mammalian nervous system, including cortex, hippocampus, thalamus, retina, cerebellum, and inferior olive. Classically, the function of electrical synapses has been associated with synchrony, logically following that continuous conductance provided by gap junctions facilitates the reduction of voltage differences between coupled neurons. Indeed, electrical synapses promote synchrony at many anatomical and frequency ranges across the brain. However, a growing body of literature shows there is greater complexity to the computational function of electrical synapses. The paired membranes that embed electrical synapses act as low-pass filters, and as such, electrical synapses can preferentially transfer spike after hyperpolarizations, effectively providing spike-dependent inhibition. Other functions include driving asynchronous firing, improving signal to noise ratio, aiding in discrimination of dissimilar inputs, or dampening signals by shunting current. The diverse ways by which electrical synapses contribute to neuronal integration merits furthers study. Here we review how functions of electrical synapses vary across circuits and brain regions and depend critically on the context of the neurons and brain circuits involved. Computational modeling of electrical synapses embedded in multi-cellular models and experiments utilizing optical control and measurement of cellular activity will be essential in determining the specific roles performed by electrical synapses in varying contexts.
电突触是神经元之间缝隙连接孔的神经生理学产物，允许电流在神经元之间双向流动。它们在整个哺乳动物神经系统中都有表达，包括大脑皮层、海马体、丘脑、视网膜、小脑和下橄榄核。传统上，电突触的功能与同步性相关，从逻辑上来说，缝隙连接提供的连续电导有助于减小耦合神经元之间的电压差。事实上，电突触在大脑的许多解剖结构和频率范围内都能促进同步性。然而，越来越多的文献表明，电突触的计算功能更为复杂。嵌入电突触的成对膜起着低通滤波器的作用，因此，电突触可以优先在超极化后传递尖峰，有效地提供尖峰依赖性抑制。其他功能包括驱动异步放电、提高信噪比、帮助区分不同的输入或通过分流电流来衰减信号。电突触对神经元整合的多种贡献方式值得进一步研究。在这里，我们综述了电突触的功能如何在不同的神经回路和脑区中变化，并严重依赖于所涉及的神经元和脑回路的背景。在多细胞模型中嵌入电突触的计算建模以及利用光学控制和测量细胞活动的实验，对于确定电突触在不同背景下所发挥的具体作用至关重要。
