I am having some difficulties with my analyses and was wondering if anybody
could offer some advice or reassurance, as I am a newcomer to fMRI analysis
of any kind.
I have read both the FEAT manual and other posts from the archives, but still
I have two groups:
Group1 = controls (scanned once)
Group2 = experimental group (scanned pre and post training).
My paradigm was separated into 2 consecutive sessions which I have
separately analysed at first level and then combined using a fixed effects
higher level analysis.
For between group analysis, for the main effects I have performed Two-
sample unpaired T-Tests for my Controls vs Pre and then again for my
Controls vs Post.
I have them performed a Repeated Measures analysis on the Pre vs Post data.
Is this correct?
I now want to look at contrasts between my groups and it is here that I am
getting really confused. I understand that I have to use contrast masking to
allow for better interpretation of my findings, but remain unsure about how to
For example I want to look at Pre (Left > Right) Vs Post (Left > Right). I
therefore want to know where the Pre group had greater activation than the
post group when looking at Left vs Right. However, my analyses are being
performed on cope files from my second level g.feat directories and therefore
only contain the (left vs right) data and not the left data and the right data
Therefore what do I use to contrast the analysis with? And do I contrast Left
> Right only with Left, and my Right > Left analysis only with right, or do I
have to contrast both???
Sorry if these seem like basic questions, but any advice will be appreciated.
Please keep responses as basic as possible :)