ts = -prePeak:1/fs:posPeak;
ts = linspace(prePeak, postPeak, 201);
But as far as I can see, you use ts only to measure its length. Then simply omit the definition and replace "length(ts)" by "201".
I'm not sure where the "201" is coming from, but I cannot know, why neural.spikes(S) has 201 elements.