Basket cell extrasynaptic inhibition modulates network oscillations (Proddutur et al., 2013)

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Accession:155601
Among the rhythmic firing patterns observed in brain, gamma oscillations, which are involved in memory formation and retrieval, are generated by networks of fast-spiking basket cells (FS-BCs) with robust interconnectivity through fast GABA synapses. Recently, we identified presence of extrasynaptic tonic GABA currents in FS-BCs and showed that experimentally-induced seizures enhance extrasynaptic tonic GABA currents and render GABA reversal potential (EGABA) depolarizing (Yu et al., 2013). Extrasynaptic GABA currents are mediated by extra- and peri-synaptically located GABAARs and can contribute to synaptic decay kinetics. Additionally, shunting rather than hyperpolarizing EGABA has been shown to increase the frequency and reduce coherence of network oscillations. Using homogeneous networks of biophysically-based, multi-compartmental model FS-BCs, we examined how the presence of extrasynaptic GABA currents and the experimentally identified seizure-induced alterations in GABA currents and EGABA modify the frequency and coherence of network firing.
Reference:
1 . Proddutur A, Yu J, Elgammal FS, Santhakumar V (2013) Seizure-induced alterations in fast-spiking basket cell GABA currents modulate frequency and coherence of gamma oscillation in network simulations. Chaos 23:046109 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Dentate gyrus basket cell;
Channel(s):
Gap Junctions: Gap junctions;
Receptor(s): GabaA;
Gene(s):
Transmitter(s): Gaba;
Simulation Environment: NEURON;
Model Concept(s): Oscillations;
Implementer(s):
Search NeuronDB for information about:  GabaA; Gaba;
/
ProdduturEtAl2013
readme.html
bgka.mod *
CaBK.mod *
ccanl.mod *
gap.mod
Gfluct2.mod *
gskch.mod *
hyperde3.mod *
ichan2.mod *
izap.mod
LcaMig.mod *
markov.mod *
nca.mod *
tca.mod *
tonic.mod *
IClamp 50% gaps 30 SYNAPSES tonicspill -74mV_0.6nA.hoc
PPSTIM 50% gaps 30 SYNAPSES tonicspill -74mV.hoc
screenshot1.png
                            
TITLE hyperde3.mod  
 
COMMENT
Chen K, Aradi I, Thon N, Eghbal-Ahmadi M, Baram TZ, Soltesz I: Persistently
modified
h-channels after complex febrile seizures convert the seizure-induced
enhancement of
inhibition to hyperexcitability. Nature Medicine, 7(3) pp. 331-337, 2001.
(modeling by Ildiko Aradi, iaradi@uci.edu)
distal dendritic Ih channel kinetics for both HT and Control anlimals
ENDCOMMENT
 
UNITS {
        (mA) =(milliamp)
        (mV) =(millivolt)
        (uF) = (microfarad)
	(molar) = (1/liter)
	(nA) = (nanoamp)
	(mM) = (millimolar)
	(um) = (micron)
	FARADAY = 96520 (coul)
	R = 8.3134	(joule/degC)
}
 
? interface 
NEURON { 
SUFFIX hyperde3 
USEION hyf READ ehyf WRITE ihyf VALENCE 1
USEION hys READ ehys WRITE ihys VALENCE 1
USEION hyhtf READ ehyhtf WRITE ihyhtf VALENCE 1
USEION hyhts READ ehyhts WRITE ihyhts VALENCE 1
RANGE  ghyf, ghys, ghyhtf, ghyhts
RANGE ghyfbar, ghysbar, ghyhtfbar, ghyhtsbar
RANGE hyfinf, hysinf, hyftau, hystau
RANGE hyhtfinf, hyhtsinf, hyhtftau, hyhtstau, ihyf, ihys
}
 
INDEPENDENT {t FROM 0 TO 100 WITH 100 (ms)}
 
PARAMETER {
      v (mV) 
      celsius = 6.3 (degC)
      dt (ms) 

	ghyfbar (mho/cm2)
	ghysbar (mho/cm2)
	ehyf (mV)
	ehys (mV)
	ghyhtfbar (mho/cm2)
	ghyhtsbar (mho/cm2)
	ehyhtf (mV)
	ehyhts (mV)
}
 
STATE {
	hyf hys hyhtf hyhts
}
 
ASSIGNED {
         
  
	ghyf (mho/cm2)
 	ghys (mho/cm2)

	ghyhtf (mho/cm2)
	ghyhts (mho/cm2)

  
	ihyf (mA/cm2)
	ihys (mA/cm2)
	ihyhtf (mA/cm2)
	ihyhts (mA/cm2)

	hyfinf hysinf hyhtfinf hyhtsinf
 	hyftau (ms) hystau (ms) hyhtftau (ms) hyhtstau (ms)
	hyfexp hysexp hyhtfexp hyhtsexp     
} 

? currents
BREAKPOINT {

	SOLVE states

	ghyf = ghyfbar * hyf*hyf
	ihyf = ghyf * (v-ehyf)
	ghys = ghysbar * hys*hys
	ihys = ghys * (v-ehys)

	ghyhtf = ghyhtfbar * hyhtf* hyhtf
	ihyhtf = ghyhtf * (v-ehyhtf)
	ghyhts = ghyhtsbar * hyhts* hyhts
	ihyhts = ghyhts * (v-ehyhts)
		
		}
 
UNITSOFF
 
INITIAL {
	trates(v)
	
	hyf = hyfinf
      hys = hysinf
	hyhtf = hyhtfinf
	hyhts = hyhtsinf
	VERBATIM
	return 0;
	ENDVERBATIM
}

? states
PROCEDURE states() {	:Computes state variables m, h, and n 
        trates(v)	:      at the current v and dt.
        
        hyf = hyf + hyfexp*(hyfinf-hyf)
        hys = hys + hysexp*(hysinf-hys)
	  hyhtf = hyhtf + hyhtfexp*(hyhtfinf-hyhtf)
	  hyhts = hyhts + hyhtsexp*(hyhtsinf-hyhts)

        VERBATIM
        return 0;
        ENDVERBATIM
}
 
LOCAL q10

? rates
PROCEDURE rates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
        LOCAL  alpha, beta, sum
       q10 = 3^((celsius - 6.3)/10)
       
	:"hyf" FAST CONTROL Hype activation system
	hyfinf =  1 / (1 + exp( (v+91)/10 ))
	hyftau = 14.9 + 14.1 / (1+exp(-(v+95.2)/0.5))

	:"hys" SLOW CONTROL Hype activation system
	hysinf =  1 / (1 + exp( (v+91)/10 ))
	hystau = 80 + 172.7 / (1+exp(-(v+59.3)/-0.83))

		:"hyhtf" FAST HT Hypeht activation system
	hyhtfinf =  1 / (1 + exp( (v+87)/10 ))
	hyhtftau = 23.2 + 16.1 / (1+exp(-(v+91.2)/0.83))

		:"hyhts" SLOW HT Hypeht activation system
	hyhtsinf =  1 / (1 + exp( (v+87)/10 ))
	hyhtstau = 227.3 + 170.7*exp(-0.5*((v+80.4)/11)^2)
}
 
PROCEDURE trates(v) {  :Computes rate and other constants at current v.
                      :Call once from HOC to initialize inf at resting v.
	LOCAL tinc
      TABLE hyfinf, hyhtfinf, hyfexp, hyhtfexp, hyftau, hyhtftau, 
		hysinf, hyhtsinf, hysexp, hyhtsexp, hystau, hyhtstau	
	DEPEND dt, celsius FROM -120 TO 100 WITH 220
                           
	rates(v)	: not consistently executed from here if usetable_hh == 1
		: so don't expect the tau values to be tracking along with
		: the inf values in hoc

	       tinc = -dt * q10
        
        hyfexp = 1 - exp(tinc/hyftau)
	  hysexp = 1 - exp(tinc/hystau)
	  hyhtfexp = 1 - exp(tinc/hyhtftau)
	  hyhtsexp = 1 - exp(tinc/hyhtstau)
}
 
FUNCTION vtrap(x,y) {  :Traps for 0 in denominator of rate eqns.
        if (fabs(x/y) < 1e-6) {
                vtrap = y*(1 - x/y/2)
        }else{  
                vtrap = x/(exp(x/y) - 1)
        }
}
 
UNITSON


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