Pattern completion was inferred if the pattern of CA3 outputs was closer to the original pattern than to some other trained pattern. model. Empirical data are then provided using an example of dominating GCs C subsets of GCs that develop abnormally and have improved excitability. Notably, these irregular GCs have been recognized in animal models of disease where DG-dependent behaviors are impaired. Collectively these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network. erforant terminals). INs will also be located in CA3 (oval). Note that the mossy materials have both huge boutons as well as filamentous extensions that make synapses, primarily onto IN. MC=mossy cell. PYR= pyramidal cell. GC=granule cell. From (Myers et al., 2013). B. The DG-CA3 network model. Abbreviations mainly because in part A. HIPP, MC and IN are constants governing connection advantages in the model. For additional details, observe (Myers & Scharfman, 2011; Myers et al., 2013). 1.2 Terminology: pattern separation and completion As noted above, CA3 pyramidal cell axons form recurrent collaterals that innervate additional CA3 pyramidal cells. Several computational models possess suggested the high degree of recurrency among pyramidal cells could support memory space storage and recall (Marr, 1971; McNaughton & Morris, 1987; Rolls, 1989a, 1989b; Rolls & Treves, 1994; Treves & Rolls, 1994; Kesner, 2007). With this look at, input patterns, representing activity inside a subset of perforant path axons, are stored in CA3 via modifiable synapses between pyramidal cells. The stored pattern is reflected by coactivity in these pyramidal cells, reminiscent of JC-1 the cell assemblies JC-1 proposed by Hebb (Hebb, 1949). To store fresh patterns for later on retrieval, most computational models of CA3 presume the presence of so-called teaching inputs, inputs that are strong enough to result in postsynaptic activity JC-1 and result in long-term synaptic plasticity between the postsynaptic cell along with other coincidentally active presynaptic cells (e.g. from entorhinal cortex). It has long been speculated the mossy materials, which form extraordinarily large and strong synapses onto proximal apical dendrites of CA3 PYR, could serve as teaching inputs (McNaughton & Morris, 1987; McNaughton & Nadel, 1990; Treves & Rolls, 1992; Rolls, 1989a, 2007). Empirical support of this idea comes from physiological recordings in which Itga10 spike trains in one mossy fiber can cause the postsynaptic CA3 pyramidal cell to reach firing threshold (von Kitzing et al., 1994; JC-1 Henze et al., 2002; Henze et al., 2002; Kobayashi & Poo, 2004). Relating to this look at, input from your entorhinal cortex via the perforant path focuses on CA3 pyramidal cells directly and also indirectly via the GC mossy materials. Sparse activity in GCs means a few GCs spike, and those GCs give rise to mossy materials that are strong enough to evoke postsynaptic activity in the pyramidal cells they target, allowing synaptic conditioning between those pyramidal cells and coactive entorhinal inputs, storing the pattern. After the storage of a pattern, if a partial or noisy version of the stored pattern is definitely offered, pyramidal cell activity in the previously-strengthened pathways can reinstate or total the stored pattern, a process termed pattern completion (e.g. (Marr, 1971; McNaughton & Morris, 1987; Rolls, 2013)). Empirical data support this idea by implicating the hippocampus, specifically CA3, in behaviors that require realizing familiar (or partially-distorted) stimuli, and which are consequently assumed to require pattern completion in neural representations (e.g.(Kesner, 2007; Neunuebel & Knierim, 2014). In addition to its part like a teacher,.