// Potassium channel from original HH model // Voltage clamp simulations with non-stationary noise analysis // UNcoupled activation particles (2-state independent particles), Diffusion approximation algorithm // See "StochHH_K5 Fb Vclamp noise.sci" for more comments stacksize('max'); nsim=200; //number of sweeps to be simulated Tstop=6; dt=0.001; //Total time and dt in ms points = round(Tstop/dt) //number of points per sweep NK=300; //number of potassium channels Vhold=-90; //voltage at t=0 Vtest=70; rand('normal') p=1; Norec = zeros(points,nsim); v = Vhold*ones(1,nsim); alpha_n=0.01*(v+55)./(1-exp(-(v+55)/10)); beta_n=0.125*exp(-(v+65)/80); n=ones(1,nsim)./(1+beta_n./alpha_n); v = Vtest*ones(1,nsim); alpha_n=0.01*(v+55)./(1-exp(-(v+55)/10)); beta_n=0.125*exp(-(v+65)/80); tic() for t = dt:dt:Tstop Norec(p,:) = NK*n.^4; p=p+1; SDn = sqrt(abs(alpha_n.*(1-n)+beta_n.*n)/(dt*NK*4)); n=n+dt*(alpha_n.*(1-n)-beta_n.*n+rand(1,nsim).*SDn); end time=toc() printf("time = %g\n",time); scf(0); clf plot(dt:dt:Tstop,Norec) scf(1); clf plot(dt:dt:Tstop,[mean(Norec,2),variance(Norec,2)]) scf(2); clf plot(mean(Norec,2),variance(Norec,2))