Abstract
Many brain regions communicate information through synchronized network activity. Electrical coupling among the dendrites of interneurons in the cortex has been implicated in forming and sustaining such activity in the cortex. Evidence for the existence of electrical coupling among cortical pyramidal cells, however, has been largely absent. A recent experimental study measured properties of electrical connections between pyramidal cells in the cortex deemed “electrotonic couplings.” These junctions were seen to occur pair-wise, sparsely, and often coexist with electrically-coupled interneurons. Here, we construct a network model to investigate possible roles for these rare, electrotonically-coupled pyramidal-cell pairs. Through simulations, we show that electrical coupling among pyramidal-cell pairs significantly enhances coincidence-detection capabilities and increases network spike-timing precision. Further, a network containing multiple pairs exhibits large variability in its firing pattern, possessing a rich coding structure.
Highlights
Synchronized neuronal activity in the cortex is essential for information processing underlying many cognitive functions, such as learning, attention, and memory formation (Wang and Buzsaki, 1996; Buzsaki and Draguhn, 2004; Wang et al, 2010)
We begin by considering the effect of electrotonic couplings (ECs) between one pair of neurons that is embedded in the downstream network and receives input from a subset of upstream IAF neurons exhibiting varying amounts of synchrony
We note that the two pyramidal cells in the network-driven electrotonic pair (NDEP) have synchronized activity due to their EC, which strongly couples the voltages of the two neurons, resulting in almost identical spike trains
Summary
Synchronized neuronal activity in the cortex is essential for information processing underlying many cognitive functions, such as learning, attention, and memory formation (Wang and Buzsaki, 1996; Buzsaki and Draguhn, 2004; Wang et al, 2010). Experimentalists and computational neuroscientists have shown that, in addition to neuronal communication via chemical synapses, electrical coupling among interneurons, local inhibitory neurons, plays an essential role in generating and maintaining synchronous activity among neurons in the cortex (Gibson et al, 1999; Beierlein et al, 2000; Chow and Kopell, 2000; Tamas et al, 2000; Traub et al, 2001; Amitai et al, 2002; Nomura et al, 2003; Bennett and Zukin, 2004; Ostojic et al, 2009) Such coupling occurs through protein channels called gap junctions that directly connect the interior contents of the cells (Revel and Karnovsky, 1967).
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