function [spikes1] = int_spikes(spikes,handles); 
%Interpolates with cubic splines to improve alignment.

w_pre=handles.w_pre;
w_post=handles.w_post;
ls = w_pre + w_post;
detect = handles.detection;
int_factor = handles.int_factor;
nspk=size(spikes,1);

s=1:size(spikes,2);
ints=1/int_factor:1/int_factor:size(spikes,2);

intspikes=zeros(1,length(ints));
spikes1=zeros(nspk,ls);
switch detect
    case 'pos'
        for i=1:nspk
            intspikes(:) = spline(s,spikes(i,:),ints);
            [maxi, iaux]=max((intspikes(w_pre*int_factor:w_pre*int_factor+8))); 
            iaux = iaux + w_pre*int_factor -1;
            spikes1(i,w_pre:-1:1) = intspikes(iaux:-int_factor:iaux-w_pre*int_factor+int_factor);
            spikes1(i,w_pre+1:ls) = intspikes(iaux+int_factor:int_factor:iaux+w_post*int_factor);

        end
    case 'neg'
        for i=1:nspk
            intspikes(:) = spline(s,spikes(i,:),ints);
            [maxi, iaux]=min((intspikes(w_pre*int_factor:w_pre*int_factor+8))); 
            iaux = iaux + w_pre*int_factor -1;
            spikes1(i,w_pre:-1:1) = intspikes(iaux:-int_factor:iaux-w_pre*int_factor+int_factor);
            spikes1(i,w_pre+1:ls) = intspikes(iaux+int_factor:int_factor:iaux+w_post*int_factor);
        end
    case 'both'
        for i=1:nspk
            intspikes(:) = spline(s,spikes(i,:),ints);
            [maxi, iaux]=max(abs(intspikes(w_pre*int_factor:w_pre*int_factor+8))); 
            iaux = iaux + w_pre*int_factor -1;
            spikes1(i,w_pre:-1:1) = intspikes(iaux:-int_factor:iaux-w_pre*int_factor+int_factor);
            spikes1(i,w_pre+1:ls) = intspikes(iaux+int_factor:int_factor:iaux+w_post*int_factor);
        end
end