Hi,
I know the definition for ROIs should be independent but there is a commonly encountered question and I would like to confirm my thinking.
Suppose in an experiment, subjects had to see a picture, maintain a working memory for it (EV1: WM), and decide if the picture was included in a probe (EV2: Decision), which consisted of 3 pictures. Researchers performed a whole-brain analysis for WM period and found that amygdala and hippocampus were activated. They then wanted to examine if both regions were also activated during / contributed to the Decision period (whole-brain analysis during Decision did not yield activations in both regions). There are 4 possible ways to define amygdala and hippocampus ROIs:
(1). Using coordinates from previous related fMRI studies, defining r=6 spherical ROIs centering at these coordinates.
(2). Using coordinates from a meta-analysis focusing on similar studies, defining r=6 spherical ROIs centering at these coordinates.
(3). Using anatomical atlas (i.e., MarsBar AAL).
(4). Using exactly the coordinates identified during the WM period, defining r=6 spherical ROIs centering at these coordinates.
I think (1)-(3) is ok but not sure if (4) is allowed or not. Is the definition of ROIs independent in (4)?
Thanks in advance.
Mike
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