Thalamocortical augmenting response (Bazhenov et al 1998)

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Accession:37819
In the cortical model, augmenting responses were more powerful in the "input" layer compared with those in the "output" layer. Cortical stimulation of the network model produced augmenting responses in cortical neurons in distant cortical areas through corticothalamocortical loops and low-threshold intrathalamic augmentation. ... The predictions of the model were compared with in vivo recordings from neurons in cortical area 4 and thalamic ventrolateral nucleus of anesthetized cats. The known intrinsic properties of thalamic cells and thalamocortical interconnections can account for the basic properties of cortical augmenting responses. See reference for details. NEURON implementation note: cortical SU cells are getting slightly too little stimulation - reason unknown.
Reference:
1 . Bazhenov M, Timofeev I, Steriade M, Sejnowski TJ (1998) Computational models of thalamocortical augmenting responses. J Neurosci 18:6444-65 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism: Thalamus;
Cell Type(s): Thalamus geniculate nucleus (lateral) principal neuron; Thalamus reticular nucleus cell; Neocortex V1 pyramidal corticothalamic L6 cell;
Channel(s): I Na,t; I T low threshold; I A; I K,Ca;
Gap Junctions:
Receptor(s): GabaA; GabaB; AMPA;
Gene(s):
Transmitter(s): Gaba; Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Synchronization; Synaptic Integration;
Implementer(s): Lytton, William [billl at neurosim.downstate.edu];
Search NeuronDB for information about:  Thalamus geniculate nucleus (lateral) principal neuron; Thalamus reticular nucleus cell; Neocortex V1 pyramidal corticothalamic L6 cell; GabaA; GabaB; AMPA; I Na,t; I T low threshold; I A; I K,Ca; Gaba; Glutamate;
: $Id: tia.mod,v 1.9 2004/06/08 21:09:11 billl Exp $
TITLE rapidly inactivating potassium current
:
:   K+ current responsible for blocking rebound low threshold spikes (LTS)
:   LOCAL GABAERGIC INTERNEURONS IN THE THALAMUS
:   Differential equations 
:
:   Model of Huguenard & McCormick, J Neurophysiol 68: 1373-1383, 1992.
:   The kinetics is described by standard equations (NOT GHK)
:   using a m4h format, according to the voltage-clamp data
:   of Huguenard, Coulter & Prince, J Neurophysiol.
:   66: 1304-1315, 1991.
:
:    - Kinetics adapted to fit the A-channel of interneuron
:    - Q10 changed to 5 and 3
:    - Time constant tau_m and tau_h from experimental data (from TC)
:    - shift parameter for fitting interneuron data, according to the
:    - voltage-clamp data from premature rat by Pape et al. J.
:    - Physiol. 1994. 
:
:   ACTIVATION FUNCTIONS FROM EXPERIMENTS (NO CORRECTION)
:
:   Reversal potential taken from Nernst Equation
:
:   Written by Jun Zhu, University of Wisconsin, August 19, 1994, at MBL, Woods Hole, MA
:

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

NEURON {
	SUFFIX ia
	USEION k  READ ek WRITE ik VALENCE 1
	RANGE gmax, i
	GLOBAL m_inf, tau_m, h_inf, tau_h, exptemp, q10
}

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

PARAMETER {
  ek
  v		(mV)
  celsius	= 36	(degC)
  gmax	= 0.0	(mho/cm2)
  exptemp= 23.5
  q10 = 3
}

STATE {
  m h
}

ASSIGNED {
	ik	(mA/cm2)
	i	(mA/cm2)
	m_inf
	tau_m	(ms)
	h_inf
	tau_h	(ms)
        tadj
}

BREAKPOINT {
	SOLVE states METHOD cnexp
	i = gmax * (m*m*m*m*h * (v-ek))
        ik = i
}

DERIVATIVE states {
	evaluate_fct(v)

	m' = (m_inf - m) / tau_m
	h' = (h_inf - h) / tau_h 
}

UNITSOFF
INITIAL {
        tadj = pow(q10,((celsius-exptemp)/10))
	evaluate_fct(v)
	m = m_inf
	h = h_inf
:
:   Activation functions and kinetics were obtained from
:   Huguenard & McCormick, and were at 35.5 deg.

}

PROCEDURE evaluate_fct(v(mV)) { 
  :   Time constants were obtained from Huguenard & McCormick
  :   not sure about 7.4 and 5.0

  m_inf = 1.0 / ( 1 + exp(-(v+60)/8.5) )
  h_inf = 1.0 / ( 1 + exp((v+78)/6.0) )

  tau_m = (1.0/  (exp((v+35.82)/19.69)+exp(-(v+79.69)/12.7)) +0.37) / tadj
: tau_m = (0.27 /(exp((v+35.8 )/19.7 )+exp(-(v+79.7 )/12.7)) +0.1)
  if (v < -63) {
    tau_h =  1.0 /(exp((v+46.05)/5)+exp(-(v+238.4)/37.45)) / tadj
:   tau_h = (0.27/(exp((v+46)   /5)+exp(-(v+238)  /37.5)))
  } else {	
    tau_h = 19.0/tadj
   :tau_h = 5.1
  }
}
UNITSON





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