How neurons communicate with each other is central to our understanding of the nervous system. Since the times of Golgi and Cajal, the roles of electrical vs. chemical forms of transmission have been much debated. While it is now well established that both electrical and chemical forms of transmission co-exist throughout the mammalian nervous system, gap junction-mediated electrical signals are found to be extremely weak compared to their chemical counterparts. Thus, how gap junctions can influence neural activity and their role in neural coding still remains poorly understood.
A research team led by Dr. Gautam Awatramani at the University of Victoria has been investigating the role of gap junctions between specific ganglion cells in the retina, which send directional information to the brain. The team’s most recent discovery, which was published in Nature Neuroscience, reveal how weak gap junction inputs are amplified and strongly influence the types of information that is sent from the eye to the brain.
Neurons connected by gap junctions often respond near simultaneously, much more often than predicted by chance. Dr. Awatramani explains, “What is surprising is synchronous spike activity requires a complex series of finely orchestrated interactions between gap junctions, chemical synapses as well as active dendritic conductances.”
Original Research Article: Trenholm S*, McLaughlin AJ*, Schwab DJ, Turner MH, Smith RG, Rieke F, Awatramani GB. Nonlinear dendritic integration of electrical and chemical synaptic inputs drives fine-scale correlations. Nat Neurosci. 2014 Dec;17(12):1759-66. doi: 10.1038/nn.3851. Epub 2014 Oct 26.
Also see: News and Views “Reading dendritic activity with gap junctions”
