Getting a weird plot

Not sure why I'm getting this this plot ... reaching out to MATLAB Gods Should look like "HH", looks like "HH Wrong"

%simulation time simulationTime = 100; %in miliseconds deltaT = 0.1; t=0:deltaT:simulationTime;

%specify the external current I changeTimes = [0]; currentLevels = [50];

% I(1:500) = currentLevels; I(501:2000) = 0; I(2001:numel(t)) = currentLevels;

%Constant Parameters gbar_K=36; gbar_Na=120; g_L=0.3; E_K=-12; E_Na=115; E_L=10.6; C=1;

%Set the initial states V=0; alpha_n = 0.01 * ( (10-V) / (exp((10-V)/10)) ); beta_n = 0.125*exp(-V/80); alpha_m = 0.1*((25-V) / (exp((25-V)/10)-1) ); beta_m = 4*exp(-V/18); alpha_h = 0.07*exp(-V/20); beta_h = 1/(exp((30-V)/10)+1);

n(1) = alpha_n/(alpha_n+beta_n); m(1) = alpha_m/(alpha_m+beta_m); h(1) = alpha_h/(alpha_h+beta_h);

for i=1:numel(t)-1 alpha_n(i) = 0.01*( (10-V(i)) / (exp((10-V(i))/10)-1)); beta_n(i) = 0.125*exp(-V(i)/80); alpha_m(i) = 0.1*( (25-V(i)) / (exp((25-V(i))/10)-1) ); beta_m = 4*exp(-V(i)/18); alpha_h = 0.07*exp(-V(i)/20); beta_h = 1/(exp((30-V(i))/10)+1);

    %Calculate the Currents
    I_Na = (m(i)^3) *gbar_Na * h(i) * (V(i)-E_Na);
    I_K = (n(i)^4 * gbar_K * (V(i)-E_K));
    I_L = g_L * (V(i)-E_L);
    I_ion = I(i) - I_K - I_Na - I_L;

    %Calclate the Derivatives
    V(i+1) = V(i) + deltaT*I_ion/C;
    n(i+1) = n(i) + deltaT*(alpha_n(i) * (1-n(i)) - beta_n(i) * n(i));
    m(i+1) = m(i) + deltaT*(alpha_m(i) * (1-m(i)) - beta_m(i) * m(i));
    h(i+1) = h(i) + deltaT*(alpha_h(i) * (1-h(i)) - beta_h(i) * h(i));
end

%Set resting potential to -70 mV

V = V-70

%Plot Voltage

plot(t,V, 'LineWidth', 3) hold on legend({'voltage'}) ylabel('Voltage (mv)') xlabel('time (ms)') title ('voltage over Time in Simulated Neuron')

%Plot Conductance

figure p1 = plot(t,gbar_K*n.^4,'LineWidth',2); hold on p2 = plot(t,gbar_Na*(m.^3).*h, 'r', 'LineWidth',2); legend([p1, p2], 'Conductance for Potassium', 'Conductance for Sodium') ylabel ('Conductance') xlabel ('time (ms)') title ('Conductance for Potassium and Sodium Ions in Simulated Neurons')

Index exceeds matrix dimensions.

Error in HH (line 49) m(i+1) = m(i) + deltaT*(alpha_m(i) * (1-m(i)) - beta_m(i) * m(i));

Thanks!