Dear Susana,
if I understand you correctly, there is no way to get a "temporal series
of activation values" with a time resolution higher than TR. Also, the
single value you got is not the "peak activation for that time period",
either.
In a fMRI experiment one usually observe each voxel in a 3D data set
exactly once per TR. Thus, you sample BOLD response in each voxel at a
sampling frequency of 1/TR. One may get a higher time resolution per
event type if you either shorten your TR (acquire less slices, smaller
FOV...) or in an event-related design where one usually acquires many
instances of BOLD responses for the same stimulus and the stimulus onset
SO is somehow randomised with respect to TR. By re-ordering your
timepoints in terms of SO, you get a peri-stimulus time histogram with a
higher time resolution than TR.
Volkmar
On Thu, 17 Aug 2006, Susana Santos wrote:
> Dear All,
>
> I am trying to obtain the activation at a given voxel during a whole TR (3 seconds). I know how to
> extract the single value that represents the peak activation for that time period, but how can I obtain
> the temporal series of activation values for the whole duration of the TR?
>
> Thanks very much in advance for your help,
> Susana
>
>
--
Volkmar Glauche
-
Department of Neurology [log in to unmask]
Universitaetsklinikum Freiburg Phone 49(0)761-270-5331
Breisacher Str. 64 Fax 49(0)761-270-5416
79106 Freiburg
|