I tried to reproduce your subject.mat files. I understand one colonn by time-series and region. I extracted (using marsbar and my data) the Bold signal in each region and I found higher values (300, 350, etc..) that correspond to intensity values.
I would like to know what represent exactly the values in your subject1.mat file. I found these values very low (0.0014, 0.00085, 0.0020, etc..).
The values are low and negative probably because we regressed out the signals from the white matter and cerebrospinal fluid as well as the motion parameters during image preprocessing. This is a common step in fMRI analyses, it’s up to you whether to apply it or not, but I recommend you do it.