How do I plot the number of peaks of each graph in the for loop?

Hello, The following code takes a step current, inputs it into a neuron which gives an output voltage, which is then converted to current and imputed into the next neuron. This is then repeated 20 times. I am trying to plot the number of voltage peaks over 0 in each of the 20 plots produced in the for loop and plot this number of peaks as a function of the neuron number(figure number). However, I keep getting the peaks for the final plot only, instead of the number of peaks for each plot vs its neuron number.

 % code
 for neuronnumber=1:1:20
    AV=AbsValue(v);
    I=Current(AV);
    [v,n,m,h]=HHmodel(ts,I);
    figure
    plot(ts,v)
    xlabel('Time (s)');
    ylabel('Output Voltage (mV)');
    title('Output Voltage vs Time (HH model)');
    spike=numel(findpeaks(v,'MinPeakHeight',0))
end
figure
plot(neronnumber,spike)
xlabel('Neuron Number')
ylabel('Number of Spikes')
title('Number of spikes vs Neuron Number')

I'm not quite sure what I am doing wrong and any help would be appreciated. thanks