Storing serial order in intrinsic excitability: a working memory model (Conde-Sousa & Aguiar 2013)

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Accession:147461
" … Here we present a model for working memory which relies on the modulation of the intrinsic excitability properties of neurons, instead of synaptic plasticity, to retain novel information for periods of seconds to minutes. We show that it is possible to effectively use this mechanism to store the serial order in a sequence of patterns of activity. … The presented model exhibits properties which are in close agreement with experimental results in working memory. ... "
Reference:
1 . Conde-Sousa E, Aguiar P (2013) A working memory model for serial order that stores information in the intrinsic excitability properties of neurons. J Comput Neurosci 35:187-99 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Working memory;
Implementer(s):
TITLE Hippocampal HH channels
:
: Fast Na+ and K+ currents responsible for action potentials
: Iterative equations
:
: Equations modified by Traub, for Hippocampal Pyramidal cells, in:
: Traub & Miles, Neuronal Networks of the Hippocampus, Cambridge, 1991
:
: range variable vtraub adjust threshold
:
: Written by Alain Destexhe, Salk Institute, Aug 1992
:
: Modifications by Arthur Houweling for use in MyFirstNEURON
: Modifications by Paulo Aguiar: vh changed from 5 to 6 - NOT ANYMORE: vh=5 as originally set

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX HH2
	USEION na READ ena WRITE ina
	USEION k READ ek WRITE ik
	RANGE gnabar, gkbar, vtraub
	RANGE m_inf, h_inf, n_inf
	RANGE tau_m, tau_h, tau_n
	RANGE m_exp, h_exp, n_exp
	RANGE ik, ina 
}


UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
}

PARAMETER {
	gnabar	= .1 	(mho/cm2)
	gkbar	= .06 	(mho/cm2)

	ena		(mV)
	ek		(mV)
	celsius		(degC)
	dt              (ms)
	v               (mV)
	vtraub	= -55	(mV)	: adjusts threshold
}

STATE {
	m h n
}

ASSIGNED {
	ina	(mA/cm2)
	ik	(mA/cm2)
	il	(mA/cm2)
	m_inf
	h_inf
	n_inf
	tau_m
	tau_h
	tau_n
	m_exp
	h_exp
	n_exp
	tadj
}


BREAKPOINT {
	SOLVE states METHOD cnexp
	ina = gnabar * m*m*m*h * (v - ena)
	ik  = gkbar * n*n*n*n * (v - ek)
}


DERIVATIVE states {   : use this for exact Hodgkin-Huxley equations
	evaluate_fct(v)
	m' = (m_inf - m) / tau_m
	h' = (h_inf - h) / tau_h
	n' = (n_inf - n) / tau_n
}

:PROCEDURE states() {	: this discretized form is more stable
:	evaluate_fct(v)
:	m = m + m_exp * (m_inf - m)
:	h = h + h_exp * (h_inf - h)
:	n = n + n_exp * (n_inf - n)
:	VERBATIM
:	return 0;
:	ENDVERBATIM
:}

UNITSOFF
INITIAL {
:
:  Q10 was assumed to be 3 for both currents
:
	tadj = 3.0 ^ ((celsius-36)/ 10 )
	evaluate_fct(v)
	m= m_inf
	h= h_inf
	n= n_inf
}

PROCEDURE evaluate_fct(v(mV)) { LOCAL a,b,v2, vh

	v2 = v - vtraub : convert to traub convention
	vh = 5
	
	a = 0.32 * (13-v2) / ( exp((13-v2)/4) - 1)
	b = 0.28 * (v2-40) / ( exp((v2-40)/5) - 1)
	tau_m = 1 / (a + b) / tadj
	m_inf = a / (a + b)

	:a = 0.128 * exp((17-v2)/18)
	:b = 4 / ( 1 + exp((40-v2)/5) )
	:tau_h = 1 / (a + b) / tadj
	:h_inf = a / (a + b)
	
	a = 0.128 * exp((17-v2-vh)/18)
	b = 4 / ( 1 + exp((40-v2-vh)/5) )
	tau_h = 1 / (a + b) / tadj
	h_inf = a / (a + b)	
	
	
	a = 0.032 * (15-v2) / ( exp((15-v2)/5) - 1)
	b = 0.5 * exp((10-v2)/40)
	tau_n = 1 / (a + b) / tadj
	n_inf = a / (a + b)

	m_exp = 1 - exp(-dt/tau_m)
	h_exp = 1 - exp(-dt/tau_h)
	n_exp = 1 - exp(-dt/tau_n)
}

UNITSON

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