Inhibitory network bistability explains increased activity prior to seizure onset (Rich et al 2020)

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Accession:266435
" ... the mechanisms predisposing an inhibitory network toward increased activity, specifically prior to ictogenesis, without a permanent change to inputs to the system remain unknown. We address this question by comparing simulated inhibitory networks containing control interneurons and networks containing hyperexcitable interneurons modeled to mimic treatment with 4-Aminopyridine (4-AP), an agent commonly used to model seizures in vivo and in vitro. Our in silico study demonstrates that model inhibitory networks with 4-AP interneurons are more prone than their control counterparts to exist in a bistable state in which asynchronously firing networks can abruptly transition into synchrony driven by a brief perturbation. This transition into synchrony brings about a corresponding increase in overall firing rate. We further show that perturbations driving this transition could arise in vivo from background excitatory synaptic activity in the cortex. Thus, we propose that bistability explains the increase in interneuron activity observed experimentally prior to seizure via a transition from incoherent to coherent dynamics. Moreover, bistability explains why inhibitory networks containing hyperexcitable interneurons are more vulnerable to this change in dynamics, and how such networks can undergo a transition without a permanent change in the drive. ..."
Reference:
1 . Rich S, Chameh HM, Rafiee M, Ferguson K, Skinner FK, Valiante TA (2020) Inhibitory Network Bistability Explains Increased Interneuronal Activity Prior to Seizure Onset. Front Neural Circuits 13:81 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism:
Cell Type(s): Abstract Izhikevich neuron;
Channel(s): I Potassium;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s): Gaba;
Simulation Environment: C or C++ program;
Model Concept(s): Synchronization; Epilepsy;
Implementer(s): Rich, Scott [sbrich at umich.edu];
Search NeuronDB for information about:  I Potassium; Gaba;
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CorticalInhibitoryNetwork-master
README.md
columnlegend.m
conv_gaussian.m
convert_spiketimes.m
getpos.m
golomb_measure.m
golomb_synch.m
InhibitoryCortex_pulse_0713.m
InhibitoryCortex_pulse_2d_FullWithRep_0905.m
InhibitoryCortex_pulse_bistabilitymeasure_zoom_repetitions_0823.m
InhibitoryCortex_pulse_stitchtogether_0709.m
InhibitoryCortex_pulse_stitchtogether_full_repetitions_0822.m
InhibitoryCortex_pulse_stitchtogether_zoom_0726.m
InhibitoryCortex_pulse_stitchtogether_zoom_repetitions_0813.m
InhibitoryCortex_pulse_zoom_0726.m
InhibitoryNetwork_cortex.sh
InhibitoryNetwork_cortex_0712.c
InhibitoryNetwork_cortex_IF_0615.c
InhibitoryNetwork_cortex_submit_0812.sh
InhibitoryNetwork_cortex_submit_zoom_0725.sh
InhibitoryNetwork_SortedRaster.m
legendflex.m
legendtitle.m
LICENSE *
mtit.m
parseArgs.m *
PlottingFICurves_v1.m
savemultfigs.m
subaxis.m *
suplabel.m
                            
function ArgStruct=parseArgs(args,ArgStruct,varargin)
% Helper function for parsing varargin. 
%
%
% ArgStruct=parseArgs(varargin,ArgStruct[,FlagtypeParams[,Aliases]])
%
% * ArgStruct is the structure full of named arguments with default values.
% * Flagtype params is params that don't require a value. (the value will be set to 1 if it is present)
% * Aliases can be used to map one argument-name to several argstruct fields
%
%
% example usage: 
% --------------
% function parseargtest(varargin)
%
% %define the acceptable named arguments and assign default values
% Args=struct('Holdaxis',0, ...
%        'SpacingVertical',0.05,'SpacingHorizontal',0.05, ...
%        'PaddingLeft',0,'PaddingRight',0,'PaddingTop',0,'PaddingBottom',0, ...
%        'MarginLeft',.1,'MarginRight',.1,'MarginTop',.1,'MarginBottom',.1, ...
%        'rows',[],'cols',[]); 
%
% %The capital letters define abrreviations.  
% %  Eg. parseargtest('spacingvertical',0) is equivalent to  parseargtest('sv',0) 
%
% Args=parseArgs(varargin,Args, ... % fill the arg-struct with values entered by the user
%           {'Holdaxis'}, ... %this argument has no value (flag-type)
%           {'Spacing' {'sh','sv'}; 'Padding' {'pl','pr','pt','pb'}; 'Margin' {'ml','mr','mt','mb'}});
%
% disp(Args)
%
%
%
%
% % Aslak Grinsted 2003

Aliases={};
FlagTypeParams='';

if (length(varargin)>0) 
    FlagTypeParams=strvcat(varargin{1});
    if length(varargin)>1
        Aliases=varargin{2};
    end
end
 

%---------------Get "numeric" arguments
NumArgCount=1;
while (NumArgCount<=size(args,2))&(~ischar(args{NumArgCount}))
    NumArgCount=NumArgCount+1;
end
NumArgCount=NumArgCount-1;
if (NumArgCount>0)
    ArgStruct.NumericArguments={args{1:NumArgCount}};
else
    ArgStruct.NumericArguments={};
end 


%--------------Make an accepted fieldname matrix (case insensitive)
Fnames=fieldnames(ArgStruct);
for i=1:length(Fnames)
    name=lower(Fnames{i,1});
    Fnames{i,2}=name; %col2=lower
    AbbrevIdx=find(Fnames{i,1}~=name);
    Fnames{i,3}=[name(AbbrevIdx) ' ']; %col3=abreviation letters (those that are uppercase in the ArgStruct) e.g. SpacingHoriz->sh
    %the space prevents strvcat from removing empty lines
    Fnames{i,4}=isempty(strmatch(Fnames{i,2},FlagTypeParams)); %Does this parameter have a value? (e.g. not flagtype)
end
FnamesFull=strvcat(Fnames{:,2});
FnamesAbbr=strvcat(Fnames{:,3});

if length(Aliases)>0  
    for i=1:length(Aliases)
        name=lower(Aliases{i,1});
        FieldIdx=strmatch(name,FnamesAbbr,'exact'); %try abbreviations (must be exact)
        if isempty(FieldIdx) 
            FieldIdx=strmatch(name,FnamesFull); %&??????? exact or not? 
        end
        Aliases{i,2}=FieldIdx;
        AbbrevIdx=find(Aliases{i,1}~=name);
        Aliases{i,3}=[name(AbbrevIdx) ' ']; %the space prevents strvcat from removing empty lines
        Aliases{i,1}=name; %dont need the name in uppercase anymore for aliases
    end
    %Append aliases to the end of FnamesFull and FnamesAbbr
    FnamesFull=strvcat(FnamesFull,strvcat(Aliases{:,1})); 
    FnamesAbbr=strvcat(FnamesAbbr,strvcat(Aliases{:,3}));
end

%--------------get parameters--------------------
l=NumArgCount+1; 
while (l<=length(args))
    a=args{l};
    if ischar(a)
        paramHasValue=1; % assume that the parameter has is of type 'param',value
        a=lower(a);
        FieldIdx=strmatch(a,FnamesAbbr,'exact'); %try abbreviations (must be exact)
        if isempty(FieldIdx) 
            FieldIdx=strmatch(a,FnamesFull); 
        end
        if (length(FieldIdx)>1) %shortest fieldname should win 
            [mx,mxi]=max(sum(FnamesFull(FieldIdx,:)==' ',2));
            FieldIdx=FieldIdx(mxi);
        end
        if FieldIdx>length(Fnames) %then it's an alias type.
            FieldIdx=Aliases{FieldIdx-length(Fnames),2}; 
        end
        
        if isempty(FieldIdx) 
            error(['Unknown named parameter: ' a])
        end
        for curField=FieldIdx' %if it is an alias it could be more than one.
            if (Fnames{curField,4})
                val=args{l+1};
            else
                val=1; %parameter is of flag type and is set (1=true)....
            end
            ArgStruct.(Fnames{curField,1})=val;
        end
        l=l+1+Fnames{FieldIdx(1),4}; %if a wildcard matches more than one
    else
        error(['Expected a named parameter: ' num2str(a)])
    end
end


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