Dear SPMers,
We are planning 10-subject studies to assess transfer of finger
movement sequence learning from Normal (N) to two Rotated settings (V
and M). We are planning to use a control condition (F) where subjects
follow random stimuli in the Normal Setting. Scanning to be conducted
at 4T, TR=3secs, whole brain imaging (each scan is of 6mm thickness
with 17 axial slices of 64x64). Because of the complexity of the
settings V and M, we don't want to put them in the same study.
Study 1: 6 runs adding to a total of 32.4 minutes
Run1: F N V N F V N V F
(each epoch lasts 36 minutes and run is 5.4 minutes.
FNV are counterbalanced but with N preceding V to
allow transfer of learning effects).
Run2, Run3, Run4, Run5, Run6 are the same as Run1
Study 2: 6 runs adding to a total of 32.4 minutes
Same as Study 1 but replacing V with M.
Subjects are scanned on the same day for Study 1 and Study 2 with a
break in between. We will ask the subjects to come again on another
day to repeat the two studies (counterbalancing the order across
subjects). We hope this repetition would make sure the transfer
effects are robust. Different sequences are generated randomly for
each study and for each subject.
Questions:
1) Do we need a control condition after each sequence condition? For
example, instead of FNV, we need to use FNFV. Our feeling is we don't,
because each condition puts the subject in a different mode even
though N and V; N amd M use the same sequence.
2) Is there any upper limit on the length of the activation/control
conditions. Most of the studies use 30s/30s type of designs. I looked
at the discussion on State-related fMRI in SPM notes [Chapter 9, pg
11]. There is an upper limit of ~1 cycle/few minutes. How long can
this be? In a motor sequencing task it is ideal to have sufficient
practice in each epoch, so 40 or 50 seconds is better but then the
cycle becomes 2 to 2.5 minutes long. Can the control condition be
shorter duration?
Please could you give your suggestions, comments and any sources to
look at for answers. I apologise for the length of the message and
appreciate any help.
Best regards
Raju Bapi
==================
Researcher, Computaional Neurobiology Group
Kawato Dynamic Brain Project
ERATO, JST, 2-2 Hikaridai, Seika
Soraku, Kyoto 619-0288 Japan
Phone: +81 774 995 1211 Fax: +81 774 95 3001
email: [log in to unmask]
URL: http://www.erato.atr.co.jp/~rajubapi
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