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
                            
%MTIT		creates a major title in a figure with many axes
%
%		MTIT
%		- creates a major title above all
%		  axes in a figure
%		- preserves the stack order of
%		  the axis handles
%
%SYNTAX
%-------------------------------------------------------------------------------
%		P = MTIT(TXT,[OPT1,...,OPTn])
%		P = MTIT(FH,TXT,[OPT1,...,OPTn])
%
%INPUT
%-------------------------------------------------------------------------------
%    FH	:	a valid figure handle		[def: gcf]
%   TXT	:	title string
%
% OPT	:	argument
% -------------------------------------------
%  xoff	:	+/- displacement along X axis
%  yoff	:	+/- displacement along Y axis
%  zoff	:	+/- displacement along Z axis
%
%		title modifier pair(s)
% -------------------------------------------
%   TPx	:	TVx
%		see: get(text) for possible
%		     parameters/values
%
%OUTPUT
%-------------------------------------------------------------------------------
% par	:	parameter structure
%  .pos :	position of surrounding axis
%   .oh	:	handle of last used axis
%   .ah :	handle of invisible surrounding axis
%   .th :	handle of main title
%
%EXAMPLE
%-------------------------------------------------------------------------------
%	subplot(2,3,[1 3]);		title('PLOT 1');
%	subplot(2,3,4); 		title('PLOT 2');
%	subplot(2,3,5); 		title('PLOT 3');
%	axes('units','inches',...
%	     'color',[0 1 .5],...
%	     'position',[.5 .5 2 2]);	title('PLOT 41');
%	axes('units','inches',...
%	     'color',[0 .5 1],...
%	     'position',[3.5 .5 2 2]);	title('PLOT 42');
%	shg;
%	p=mtit('the BIG title',...
%	     'fontsize',14,'color',[1 0 0],...
%	     'xoff',-.1,'yoff',.025);
% % refine title using its handle <p.th>
%	set(p.th,'edgecolor',.5*[1 1 1]);

% created:
%	us	24-Feb-2003		/ R13
% modified:
%	us	24-Feb-2003		/ CSSM
%	us	06-Apr-2003		/ TMW
%	us	13-Nov-2009 17:38:17

%-------------------------------------------------------------------------------
function	par=mtit(varargin)

		defunit='normalized';
	if	nargout
		par=[];
	end

% check input
	if	nargin < 1
		help(mfilename);
		return;
	end
	if	isempty(get(0,'currentfigure'))
		disp('MTIT> no figure');
		return;
	end

		vl=true(size(varargin));
	if	ischar(varargin{1})
		vl(1)=false;
		figh=gcf;
		txt=varargin{1};
	elseif	any(ishandle(varargin{1}(:)))		&&...
		ischar(varargin{2})
		vl(1:2)=false;
		figh=varargin{1};
		txt=varargin{2};
	else
		error('MTIT> invalid input');
	end
		vin=varargin(vl);
		[off,vout]=get_off(vin{:});

% find surrounding box
		ah=findall(figh,'type','axes');
	if	isempty(ah)
		disp('MTIT> no axis');
		return;
	end
		oah=ah(1);

		ou=get(ah,'units');
		set(ah,'units',defunit);
		ap=get(ah,'position');
	if	iscell(ap)
		ap=cell2mat(get(ah,'position'));
	end
		ap=[	min(ap(:,1)),max(ap(:,1)+ap(:,3)),...
			min(ap(:,2)),max(ap(:,2)+ap(:,4))];
		ap=[	ap(1),ap(3),...
			ap(2)-ap(1),ap(4)-ap(3)];

% create axis...
		xh=axes('position',ap);
% ...and title
		th=title(txt,vout{:});
		tp=get(th,'position');
		set(th,'position',tp+off);
		set(xh,'visible','off','hittest','on');
		set(th,'visible','on');

% reset original units
		ix=find(~strcmpi(ou,defunit));
	if	~isempty(ix)
	for	i=ix(:).'
		set(ah(i),'units',ou{i});
	end
	end

% ...and axis' order
		uistack(xh,'bottom');
		axes(oah);				%#ok

	if	nargout
		par.pos=ap;
		par.oh=oah;
		par.ah=xh;
		par.th=th;
	end
end
%-------------------------------------------------------------------------------
function	[off,vout]=get_off(varargin)

% search for pairs <.off>/<value>

		off=zeros(1,3);
		io=0;
	for	mode={'xoff','yoff','zoff'};
		ix=strcmpi(varargin,mode);
	if	any(ix)
		io=io+1;
		yx=find(ix);
		ix(yx+1)=1;
		off(1,io)=varargin{yx(end)+1};
		varargin=varargin(xor(ix,1));
	end
	end
		vout=varargin;
end
%-------------------------------------------------------------------------------

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