Geon 6. Local Synchronization via Gap Junctions MT


Like other types of oscillations or waves, a neural oscillation is also characterized by phase, which specifies the initial point of the oscillation. A group of neurons are "synchronized" or "phase locked" if they oscillate at the same frequency and phase (see this article for more details). To synchronize, neurons must be "coupled", namely, they must interact with each other, or with the same oscillating source. Three forms of interactions have been identified: (1) via gap junctions (this chapter), (2) via GABAergic interneurons (Chapter 7) and (3) via ephaptic coupling (Chapter 8).


Figure 1. The gap junction. A gap junction channel is an intercellular channel formed by connection of two hemichannels. Each hemichannel is composed of six connexin proteins. The gap junctions allow direct exchange of ions (and thus membrane voltage) among connected cells. They are also called "electrical synapses". [Image source: Wikipedia]

Signal transmission through gap junctions (electrical synapses) is much faster than chemical synapses. Furthermore, the electrical coupling is bidirectional, which allows rapid reciprocal exchange of membrane voltage among connected cells. For these reasons, gap junctions are commonly used for local synchronization, as observed in the lateral geniculate nucleus that generates alpha rhythms (Hughes et al., 2011), in the dorsal hippocampus that exhibits theta rhythms (Bissiere et al., 2011), and among GABAergic interneurons that produce gamma rhythms (Traub et al., 2001). Astrocytes are also interconnected by gap junctions (Orellana and Stehberg, 2014), which mediate the synchronization of Ca2+ signals known as "calcium waves".


Author: Frank Lee
First published: February 13, 2013
Last updated: August, 2018