spiketimes=dt*find(spikes);
isis=diff(spiketimes);
cv=std(isis)/mean(isis)

sum=0.0;
for i=2:length(isis)
    sum = sum + sqrt((isis(i)-isis(i-1))*(isis(i)-isis(i-1)))/(isis(i)+isis(i-1))*(2.0);
end
sum = sum /length(isis);
cv2=sum