% Spike adaptation by erg-like K+ current. If girbar is altered (0.5->0), % spike discharge will be changed. % Written by Dr. Sheng-Nan Wu, Dept Physiol, Natl Cheng Kung U Med Coll. % Ref: Chiesa et al., J Physiol 1997;501:313-318 % Initial values of the variables init v=-72.0, nK=0.288, hK=0.367, mNa=0.041, hNa=0.844, nIR=0.003, rIR=0.282 % Values of the model parameters params iapp=1.2, cm=1, gnabar=15, gkbar=2.5, girbar=0.5, gl=0.05, vna=50, vk=-80, vir=-80, vl=-80 % Gating functions alphaNam(v) = 0.1*(v+40)/( 1 - exp(-0.09*(v+40))) betaNam(v) = 4*exp(-0.055*(v+70)) mNainf(v) = 1/(1+betaNam(v)/alphaNam(v)) tauNam(v) = 1/(alphaNam(v) + betaNam(v)) alphaNah(v) = 0.07*exp(-0.05*(v+70)) betaNah(v) = 1/( 1 + exp(-0.09*(v+25)) ) hNainf(v) = 1/(1+betaNah(v)/alphaNah(v)) tauNah(v) = 1/(alphaNah(v) + betaNah(v)) alphaKn(v) = 0.01*(v + 60)/(1 - exp(-0.1*(V + 60))) betaKn(v) = 0.125*exp(-0.0125*(V + 70)) nKinf(v) = 1/(1+betaKn(v)/alphaKn(v)) tauKn(v) = 1/(alphaKn(v) + betaKn(v)) alphaKh(v) = 0.001*exp(-0.04*(v+70)) betaKh(v) = 0.001*exp(-0.0195*(v+40)) hKinf(v) = 1/(1+betaKh(v)/alphaKh(v)) tauKh(v) = 1/(alphaKh(v) + betaKh(v)) alphaIRn(v) = 0.09/(1+exp(0.11*(v+100))) betaIRn(v) = 0.00035*exp(0.07*(v+25)) nIRinf(v) = 1/(1+betaIRn(v)/alphaIRn(v)) tauIRn(v) = 1/(alphaIRn(v) + betaIRn(v)) alphaIRr(v) = 30/(1+exp(0.04*(v+230))) betaIRr(v) = 0.15/(1+exp(-0.05*(v+120))) rIRinf(v) = 1/(1+betaIRr(v)/alphaIRr(v)) tauIRr(v) = 1/(alphaIRr(v) + betaIRr(v)) % Apply current injection par tpulse=610 par tfirst=10 istim = iapp*(heav(t-tfirst)-heav(t-tpulse)) % The differential equations v' = -(gnabar*mNa^3*hNa*(v-vna) + gkbar*nK^4*hK*(v-vk) + girbar*nIR*rIR*(v-vir) + gl*(v-vl) - istim)/cm mNa' = (mNainf(v) - mNa)/tauNam(v) hNa' = (hNainf(v) - hNa)/tauNah(v) nK' = (nKinf(v) - nK)/tauKn(v) hK' = (hKinf(v) - hK)/tauKh(v) nIR' = (nIRinf(v) - nIR)/tauIRn(v) rIR' = (rIRinf(v) - rIR)/tauIRr(v) % Numerical and plotting parameters for xpp @xlo=0, xhi=700, ylo=-90, yhi=+60, total=700, dt=0.05, method=Euler, LT=1 d