MATLAB Answers

Problem using ODE45 - current not recognized

2 views (last 30 days)
Samuele Bolotta
Samuele Bolotta on 6 Mar 2021
Commented: Samuele Bolotta on 6 Mar 2021
I am using this function:
%Constants set
Cm=0.01; % Membrane Capcitance
dt=0.01; % Time Step ms
t=0:dt:25; %Time Array ms
I = zeros (145,1); %Applied constant
I(40:50,1) = 0.1; %Applied constant
V=-60; % Initial Membrane voltage
m=alpham(V)/(alpham(V)+betam(V)); % Initial m-value
n=alphan(V)/(alphan(V)+betan(V)); % Initial n-value
h=alphah(V)/(alphah(V)+betah(V)); % Initial h-value
y0=[V;n;m;h];
tspan = [0,max(t)];
%Matlab's ode45 function
[time,V] = ode45(@ODEMAT,tspan,y0);
OD=V(:,1);
ODn=V(:,2);
ODm=V(:,3);
ODh=V(:,4);
%% Plots
figure
subplot(3,1,1)
plot(time,OD);
legend('ODE45 solver');
xlabel('Time (ms)');
ylabel('Voltage (mV)');
title('Voltage Change for Hodgkin-Huxley Model');
subplot(3,1,2)
plot(time,I);
legend('Current injected')
xlabel('Time (ms)')
ylabel('Ampere')
title('Current')
subplot(3,1,3)
plot(time,[ODn,ODm,ODh]);
legend('ODn','ODm','ODh');
xlabel('Time (ms)')
ylabel('Value')
title('Gating variables')
With ODEMAT being:
function [dydt,I] = ODEMAT(t,y)
%Constants
ENa=55.17; % mv Na reversal potential
EK=-72.14; % mv K reversal potential
El=-49.42; % mv Leakage reversal potential
gbarNa=1.2; % mS/cm^2 Na conductance
gbarK=0.36; % mS/cm^2 K conductance
gbarl=0.003; % mS/cm^2 Leakage conductance
I = zeros (145,1); %Applied constant
I(40:50,1) = 0.1; %Applied constant
Cm = 0.01; % Capacitance
% Values set to equal input values
V = y(1);
n = y(2);
m = y(3);
h = y(4);
gNa = gbarNa*m^3*h;
gK = gbarK*n^4;
gL = gbarl;
INa=gNa*(V-ENa);
IK=gK*(V-EK);
Il=gL*(V-El);
for curr = 1:length(I)
dydt = [((1/Cm)*(I(curr)-(INa+IK+Il))); % This is voltage
alphan(V)*(1-n)-betan(V)*n; %This is gating conductance A
alpham(V)*(1-m)-betam(V)*m; %This is gating conductance B
alphah(V)*(1-h)-betah(V)*h]; %This is gating conductance C
end
end
So what I'm trying to do here is see what happens to voltage and gating conductances when current I switched from 0 to 0.1 (at timestep 40 until 50). However, it looks like the function doesn't really take 0.1 as input, and keeps using 0 instead. Where am I getting it wrong? I also attach the six alpha and beta functions.
Thanks,
Samuele

Answers (1)

Star Strider
Star Strider on 6 Mar 2021
I cannot run the posted code:
Unrecognized function or variable 'alpham'.
The others also appear to be missing.
That aside, if ‘I’ is a function of ‘t’, it needs to be stated as such.
  1 Comment
Samuele Bolotta
Samuele Bolotta on 6 Mar 2021
Yes sorry, I uploaded the six functions in the zip file. Here they are!

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by