High frequency oscillations in a hippocampal computational model (Stacey et al. 2009)

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Accession:135902
"... Using a physiological computer model of hippocampus, we investigate random synaptic activity (noise) as a potential initiator of HFOs (high-frequency oscillations). We explore parameters necessary to produce these oscillations and quantify the response using the tools of stochastic resonance (SR) and coherence resonance (CR). ... Our results show that, under normal coupling conditions, synaptic noise was able to produce gamma (30–100 Hz) frequency oscillations. Synaptic noise generated HFOs in the ripple range (100–200 Hz) when the network had parameters similar to pathological findings in epilepsy: increased gap junctions or recurrent synaptic connections, loss of inhibitory interneurons such as basket cells, and increased synaptic noise. ... We propose that increased synaptic noise and physiological coupling mechanisms are sufficient to generate gamma oscillations and that pathologic changes in noise and coupling similar to those in epilepsy can produce abnormal ripples."
Reference:
1 . Stacey WC, Lazarewicz MT, Litt B (2009) Synaptic noise and physiological coupling generate high-frequency oscillations in a hippocampal computational model. J Neurophysiol 102:2342-57 [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 CA3 pyramidal GLU cell; Hippocampus CA1 interneuron oriens alveus GABA cell; Hippocampus CA1 basket cell;
Channel(s): I Na,t; I A; I K; I h;
Gap Junctions: Gap junctions;
Receptor(s): GabaA; AMPA; NMDA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Oscillations;
Implementer(s): Lazarewicz, Maciej [mlazarew at gmu.edu]; Stacey, William [wstacey at med.umich.edu];
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; Hippocampus CA3 pyramidal GLU cell; Hippocampus CA1 interneuron oriens alveus GABA cell; GabaA; AMPA; NMDA; I Na,t; I A; I K; I h;
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//
// NOTICE OF COPYRIGHT AND OWNERSHIP OF SOFTWARE
//
// Copyright 2010, The University Of Michigan
// 	
//   All rights reserved.
//   For research use only; commercial use prohibited.
//   No Distribution without permission of William Stacey
//   wstacey@umich.edu
//
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


//This is the file in which I alter the synaptic strength (gmax) for all synaptic and gap connections.
// gmax =0 turns off the synapse.  I need to manually change the gmax within this file to change these parameters
//I have indicated below the relative strengths and weights used

// taken from Tort et al Kopell 2007 paper, TABLE 2
// preCell, postCell, synName, tao1, tao2, Erev, modFileName, synLocSec, synLoc, Npre, gmax, gmaxUnits, delay, r
// gmaxUnits 0-mS, 1-mS/cm2

//table 1 says Goe 5, Gie 5, Goi 0.1, Gii 0.3, Gi0 0.8, Geo 1, Gei 0.4, 
//table 2 says     10,    5,     0.1,    0.2,      0.8,     0.3,   0.1.   Both also have diff Iapp

// IE   the paper says this should be 0.7, 9.1 not 1.5 8.0, 
//pre,post,synName,tao1,tao2, Erev, modFileName, synLocSec, synLoc,Npre, 	gmax, gmaxUnits, delay, r



//THIS IS THE PRIMARY FEEDBACK SYNAPSE FROM BASKETS TO PYR
//NOTE THAT DUE TO SCALING, the gmax is divided by 20 in the network, thus "5.5" is actually 0.275 nS
Bask,	Pyr,	GABA,	1.5,	8.0,	-80,	Exp2Syn,		0,	1.0,	-1,	 	5.5,	0,	1.5,	-1
// II
Bask,	Bask,	GABA,	1.5,	8.0,	-80,	Exp2Syn,		0,	0.5,	0,		0.0,	1,	1.5,	-1

// EI     7/27/09 change was to change the r below from 0 to different levels  up to 0.5, most between 0 to 0.1 (suppl fig)
//THIS IS THE FEEDFORWARD FROM PYR TO BASK.  
Pyr,	Bask,	NMDA,	25,	250,	0,	Exp2SynNMDA,	0,	0.5,	10,		0.5,	1,	1.5,	0
//OE
//not used
OLM,	Pyr,	GABA,	0.2,	20,	-80,	Exp2Syn,		3,	1.0,	0,		0.0,	0,	2,		-1
// OI
//not used
OLM,	Bask,	GABA,	0.2,	20,	-80,	Exp2Syn,		0,	0.5,	0,	 	0.0,	1,	0.1,	-1
// IO
//not used
Bask,	OLM,	GABA,	1.5,	8.0,	-80,	Exp2Syn,		0,	0.5,	0,	 	3.5,	1,	0.1,	-1
// EO
//not used
Pyr,	OLM,	NMDA,	5,	100,	0,	Exp2SynNMDA,	0,	0.5,	0,		2.1,	1,	0.1,	1
//Pyr,	Bask,	AMPA,	0.05,	5.3,	0,		Exp2Syn,		0,	0.5,	40,		0,	1,	0.1,	-1
//Pyr,	OLM,	AMPA,	0.05,	5.3,	0,		Exp2Syn,		0,	0.5,	40,		0,	1,	0.1,	-1

//below are the two noise synapses, onto the Pyr and Bask cells
Noise, Pyr, AMPA, 0.05, 5.3, 	0, 	Exp2Syn, 		1, 	0.5, 	1, 		0.1, 	1, 	0.1, 	-1
// I had originally placed the gmax at 5.5 like the bask to pyr, and it gave 10 ms long response. Then I
// switched it to 0.4 like EI, but this was arbitrary.  It made an AP every time.
// so now I've switched it to 0.1 to be "small" synaptic events
Noise, Bask, AMPA, 0.05, 5.3, 0, 	Exp2Syn, 		0, 	0.5, 	1, 		0.1, 	1, 	0.1, 	-1


//This is a synaptic signal from elsewhere, synapsing on A1 of the pyr cells, with high signal strength
//it is also used for rec synapses, ####delay is only 0.1 ms
Pyr, Pyr, AMPA,  0.05, 5.3, 0, Exp2Syn, 		1, 	0.5, 	1, 		0.1, 	1, 	0.1, 	-1

//for these gap junctions, the only items of interest are the synLocSec and gmax.  as of 6/08 the LocSec is not implemented
//it would take some tweaking to use it, as the synparamset is not freely accessible during the connectnetwork()
Bask, Bask,   	gap, 	0, 0, 0, 	Exp2Syn, 		0, 	0.5, 	1, 		.000, 	1, 	0.1, 	-1
//for bask, .0001 is tight coupling, .00001 is very loose
Pyr, Pyr,   	gap, 	0, 0, 0, 	Exp2Syn, 		1, 	0.5, 	1, 		0.000, 	1, 	0.1, 	-1
//for pyr, .01 is high coupling, .001 is very low


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