Let's say your cell is called data and this is a 1 by 4 cell array with each cell containing column vectors of size 685 x 1. You can access the data directly using the following code:
data{1,1}(15:25,1)
data{1,2}(15:25,1)
data{1,3}(15:25,1)
data{1,4}(15:25,1)
You could also take rows 15:25 from each cell in your cell array as follows:
numarray=cell2mat(cellfun(@(x) x(15:25), data, 'UniformOutput', false))
plot(numarray)
TLDR;
If your cells are always the same size you can do the following:
numarray=cell2mat(data);
plot(numarray(15:25,:))
