[FieldTrip] Neighborhood of voxels in the volume source space

[Lin Wang]

Hi Jan-Mathijs,

Thank you very much for your response.

I defined the dipole positions with a regular 3D grid, with a dimension of
17*20*17 (following https://www.fieldtriptoolbox.org/tutorial/sourcemodel/).
This gives me 5780 grid points in total, with 2982 grid points inside of
the brain.

You mentioned that 'the neighbourhood is implicit in their order', so can I
do the following for the searchlight type of analysis:
(1) select only the activation of the 2982 grid points
(2) conduct analysis to every 10 grid points that are next to each other
(3) loop through all the 2982 grid points

Thank you again for your input!
Lin


On Fri, 19 Mar 2021 at 03:57, Schoffelen, J.M. (Jan Mathijs) <
jan.schoffelen at donders.ru.nl> wrote:

> Hi Lin,
>
> The answer to your question depends on the topology of the source space.
> If the dipole positions are defined on a regular 3D grid, the
> neighbourhood is implicit in their order.
> If the dipole positions are defined on a cortical mesh (that includes a
> triangulation), the neighbourhood can be determined from the triangulation.
>
> Best wishes,
> Jan-Mathijs
>
>
> On 18 Mar 2021, at 01:59, Lin Wang <wanglinsisi at gmail.com> wrote:
>
> Hi field excerpts,
>
> I'd like to implement a searchlight type of multivariate analysis in the
> MEG source localized data, but I don’t know where to find the information
> about neighboring voxels for each voxel.
>
> I guess this is also relevant to the definition of the neighborhood when
> conducting cluster-based permutation tests in the source space.
>
> Could anyone help me?
>
> Thank you very much!
> Lin
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