Normal ripples, abnormal ripples, and fast ripples in a hippocampal model (Fink et al. 2015)

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Accession:182134
"...We use a computational model of hippocampus to investigate possible network mechanisms underpinning normal ripples, pathological ripples, and fast ripples. Our results unify several prior findings regarding HFO mechanisms, and also make several new predictions regarding abnormal HFOs. We show that HFOs are generic, emergent phenomena whose characteristics reflect a wide range of connectivity and network input. Although produced by different mechanisms, both normal and abnormal HFOs generate similar ripple frequencies, underscoring that peak frequency is unable to distinguish the two. Abnormal ripples are generic phenomena that arise when input to pyramidal cells overcomes network inhibition, resulting in high-frequency, uncoordinated firing. In addition, fast ripples transiently and sporadically arise from the precise conditions that produce abnormal ripples. Lastly, we show that such abnormal conditions do not require any specific network structure to produce coherent HFOs, as even completely asynchronous activity is capable of producing abnormal ripples and fast ripples in this manner. These results provide a generic, network-based explanation for the link between pathological ripples and fast ripples, and a unifying description for the entire spectrum from normal ripples to pathological fast ripples."
Reference:
1 . Fink CG, Gliske S, Catoni N, Stacey WC (2015) Network Mechanisms Generating Abnormal and Normal Hippocampal High-Frequency Oscillations: A Computational Analysis. eNeuro [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism: Hippocampus;
Cell Type(s): Hippocampus CA1 pyramidal GLU cell; Hippocampus CA1 basket cell;
Channel(s): I Na,t; I A; I K; I h;
Gap Junctions: Gap junctions;
Receptor(s): GabaA; NMDA; Glutamate;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Oscillations; Epilepsy;
Implementer(s): Fink, Christian G. [cgfink at owu.edu]; Gliske, Stephen [sgliske at umich.edu]; Stacey, William [wstacey at med.umich.edu];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; GabaA; NMDA; Glutamate; I Na,t; I A; I K; I h;
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//
// NOTICE OF COPYRIGHT AND OWNERSHIP OF SOFTWARE
//
// Copyright 2007, The University Of Pennsylvania
// 	School of Engineering & Applied Science.
//   All rights reserved.
//   For research use only; commercial use prohibited.
//   Distribution without permission of Maciej T. Lazarewicz not permitted.
//   mlazarew@seas.upenn.edu
//
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



begintemplate GapObj

public add, get, getloc, addVar, remove_all, addPerArea, gapList

objref  gapList, loc
        



// =================================================================================================
//
// init()
//
// =================================================================================================
proc init() {
    gapList = new List()
    loc = new SectionRef()
}




// =================================================================================================
//
// add(sec ref preSynCell, ggap (nS))
//
// =================================================================================================
proc add() {
    
    if (numarg()==1) {
    
        loc.sec gapList.prepend(new HalfGap(0.5))
        
        gapList.object(0).g = $1
        //$o1.sec setpointer gapList.object(0).vgap, v(0.5)
        
    }else{
    
        print "USAGE: add(sec ref preSynCell, ggap (nS))"
    
    }
}




// =================================================================================================
//
// addPerArea(sec ref preSynCell, ggap (mS/cm2))
//
// =================================================================================================
proc addPerArea() {
    
    if (numarg()==2) {
    
        loc.sec gapList.prepend(new HalfGap(0.5))
        
        loc.sec gapList.object(0).ggap = $2 * area(0.5) * 1e-2 // -> nS 1e-8 * 1e6
        $o1.sec setpointer gapList.object(0).vgap, v(0.5)
        
    }else{
    
        print "USAGE: add(sec ref preSynCell, ggap (mS/cm2))"
    
    }
}



// =================================================================================================
//
// remove_all()
//
// ================================================================================================
proc remove_all() {

    gapList.remove_all()
}




// =================================================================================================
//
// addVar()
//
// ================================================================================================
proc addVar() {
    
    if (numarg()==2) {
    
        loc.sec gapList.prepend(new HalfGap(0.5))
        
        gapList.object(0).ggap = $2
        loc.sec setpointer gapList.object(0).vgap, $&1
        
    }else{
    
        print "USAGE: addGap(&var, ggap (nS))"
    
    }
}




// =================================================================================================
//
// getloc()
//
// ================================================================================================
proc getloc() {
    
    loc.sec print secname() 
}




// =================================================================================================
//
// get()
//
// ================================================================================================
proc get() {

    for i=0, gapList.count()-1 {
        loc.sec printf("%d, %s, vpre= %s, ggap= %g uS, loc= %s\n", i, gapList.object(i), gapList.object(i).vpre, gapList.object(i).ggap, secname())
    }
}

endtemplate GapObj

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