Hi Reza,

Your interpretation of the timing is correct. The validation segment in
each movie scan was shifted by 40-200ms for the "v2" version. This was done
in order to make that final 83 second clip begin precisely at the start of
the next TR for all 4 movie sessions.

Given HRF variability, ignoring this change will probably not adversely
impact most analyses.

-Keith


On Fri, May 31, 2019 at 9:05 PM Reza Rajimehr <rajim...@gmail.com> wrote:

> Hi,
>
> The HCP S1200 Reference Manual says that there are two versions of 4 movie
> files. Some subjects have been scanned with one version, and the remaining
> subjects have been scanned with another version. Version 2 includes these
> changes:
>
> 7T_MOVIE1_CC1_v2 remains unchanged.
>
> 7T_ MOVIE2_HO1_v2 removed 1 frame of rest before the validation clip.
>
> 7T_MOVIE3_CC2_v2 removed 5 frames of rest before the validation clip.
>
> 7T_MOVIE4_HO2_v2 added 4 frames of rest before the validation clip.
>
> Here *frame* is a frame of the movie, right?
>
> Assuming that the movies are ~25 frames per second, the deviations are
> between 0 and ~200 ms in each movie file. Considering the TR of one second
> and the slow hemodynamic BOLD responses, these deviations are negligible,
> and we can possibly ignore them when concatenating time-series data across
> all subjects. Would you agree?
>
> Thanks,
> Reza
>
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