Synchrony and so much more: Diverse roles for electrical synapses in neural circuits

Abstract

Electrical synapses are gap junctions between neurons that are ubiquitous across brain regions and species. The biophysical properties of most electrical synapses are relatively simple—transcellular channels allow nearly ohmic, bidirectional flow of ionic current. Yet these connections can play remarkably diverse roles when placed into different neural circuit contexts. Here I review recent findings illustrating how electrical synapses may excite or inhibit, synchronize or desynchronize, augment or diminish rhythms, phase-shift, detect coincidences, enhance signals relative to noise, adapt, and interact with nonlinear membrane and transmitter-release mechanisms. Most of these functions are likely to be widespread in central nervous systems.

Exact firing rate model reveals the differential effects of chemical versus electrical synapses in spiking networks

“…Such oscillations are profoundly shaped by the presence of chemical synapses [1]. An increasing number of experimental studies indicate both the prevalence and functional importance of electrical synapses (formed by gap junctions between neurons) in many diverse regions of central nervous systems, especially in inhibitory interneurons [2][3][4]. Electrical synapses participate in mediating synchronization of neuronal network activity [5,6], suggesting that electrical interaction may be interrelated with the generation of oscillations via chemical transmission.…”

Estrus-Cycle Regulation of Cortical Inhibition

“…The present study, along with the work of other authors (Froemke, 2015;O'Donnell et al, 2017), suggest that the balance of excitation and inhibition is much more dynamic than previously thought and is unlikely to be the only pillar on which the stability of cortical activity rests. For example, negative feedback mechanisms such as the mutual inhibition of interneurons (Connors, 2017) might greatly contribute to the stability of cortical activity despite the absence of an accurate balance of excitation and inhibition. Although studies of cortical E/I balance in the female brain are few, it is interesting to note that a recent examination of estrogen-dependent development of inhibition was reported without a change in excitation (Piekarski et al, 2017).…”

The development of local circuits in the neocortex: recent lessons from the mouse visual cortex

“…This process produces clonally related sister neurons arising from the same RGP that may represent the basis of the cortical column [33]. Gap junctions, which mediate coordinated electrical activity and the passage of small molecules among connected cells (for review, see [34]), preferentially connect vertically aligned, clonally related neurons through the first postnatal week before disappearing by postnatal day (P)6 [35,36 •• ] (Figure 1, P0–P6 panel ). These clonally related sister neurons go on to preferentially form chemical synaptic connections after the initial electrical connections have been eliminated [35,37].…”