[FieldTrip] Source localization

Lilla.Magyari at mpi.nl Lilla.Magyari at mpi.nl
Fri Jan 18 16:43:25 CET 2013


Hi Casper,

I think it is really difficult to figure only from the error message what
the problem is. I think it would be also useful to see the inputs (cfg,
and your data) of ft_sourceplot. Could you just send me how your cfg and
your data-structure looks like? (I mean that you do not need to send the
actual data, just the screen output of disp(data) and disp(cfg)).

Best,
Lilla


> Dear Fieldtrippers,
>
> I've asked this question earlier, but either it got lost due to technical
> reasons, or the people who actually understand what's happening here were
> on vacation, so here it is again:
>
> I've been trying to do a source analysis on a dataset with two conditions,
> mostly following the tutorials and examples from the Fieldtrip site, and
> come upon a problem; it won't plot. While the source analysis is not an
> essential component of the analysis of this dataset (it's more along the
> lines of "let's see if I can do this"), and I don't expect any result
> other
> than something like "there might be a source in the left hemisphere", I'd
> still would like to found out why it's not working.
>
> Essentially, I create a standard headmodel cause I don't have individual
> MRI's from the "Subject1.mri"-example, using ft_volumesegment,
> ft_prepare_headmodel and ft_prepare_sourcemodel, and try to get Fieldtrip
> to find sources based on individual EEG-datasets using ft_freqanalysis
> (with cfg.method = 'mtmfft') and ft_sourceanalysis.
> After that, I use ft_sourcegrandaverage to produce, well, a grand average
> source, and feed this via ft_sourceinterpolate to ft_sourceplot.
>
> Now, ft_sourceplot has three plotting possibilities: slice, ortho, and
> surface. Initially I tried to get the ortho-option to work, but this gave
> the following error:
> *Attempted to access dim(3); index out of bounds because numel(dim)=2.*
> *Error in ==> cornerpoints at 11
> *
> *Error in ==> ft_plot_slice at 157
> *
>
> So, I tried the surf-option, which gave me this:
> *Undefined function or variable "val".*
> *Error in ==> ft_sourceplot at 1174
> *
>
> And finally, I tried the slice-option, which gave one of two errors (which
> seems to be based on how many slices I requested):
> *Out of memory*
> Which is pretty damn impressive since I've got 8GB of RAM and a pagefile
> topping of at 40GB
> Or, the mildly disconcerting:
> *Matlab has encountered an internal error and has to close*
> Which seems to have been caused by a so-called *"Segmentation violation"
> *
>
> Can anyone offer any insight in these errors? I think I'm doing something
> wrong pretty early on, but have no idea what it is.
>
> Sincerely,
>
> Casper van Heck
>
>
> On Fri, Dec 21, 2012 at 1:43 PM, Casper van Heck
> <caspervanheck at gmail.com>wrote:
>
>> Dear Fieldtrippers,
>>
>> I've been trying to do a source analysis on a dataset with two
>> conditions,
>> mostly following the tutorials and examples from the Fieldtrip site, and
>> come upon a problem; it won't plot. While the source analysis is not an
>> essential component of the analysis of this dataset (it's more along the
>> lines of "let's see if I can do this"), and I don't expect any result
>> other
>> than something like "there might be a source in the left hemisphere",
>> I'd
>> still would like to found out why it's not working.
>>
>> Essentially, I create a standard headmodel cause I don't have individual
>> MRI's from the "Subject1.mri"-example, using ft_volumesegment,
>> ft_prepare_headmodel and ft_prepare_sourcemodel, and try to get
>> Fieldtrip
>> to find sources based on individual EEG-datasets using ft_freqanalysis
>> (with cfg.method = 'mtmfft') and ft_sourceanalysis.
>> After that, I use ft_sourcegrandaverage to produce, well, a grand
>> average
>> source, and feed this via ft_sourceinterpolate to ft_sourceplot.
>>
>> Now, ft_sourceplot has three plotting possibilities: slice, ortho, and
>> surface. Initially I tried to get the ortho-option to work, but this
>> gave
>> the following error:
>> *Attempted to access dim(3); index out of bounds because numel(dim)=2.*
>> *Error in ==> cornerpoints at 11
>> *
>> *Error in ==> ft_plot_slice at 157
>> *
>>
>> So, I tried the surf-option, which gave me this:
>> *Undefined function or variable "val".*
>> *Error in ==> ft_sourceplot at 1174
>> *
>>
>> And finally, I tried the slice-option, which gave one of two errors
>> (which
>> seems to be based on how many slices I requested):
>> *Out of memory*
>> Which is pretty damn impressive since I've got 8GB of RAM and a pagefile
>> topping of at 40GB
>> Or, the mildly disconcerting:
>> *Matlab has encountered an internal error and has to close*
>> Which seems to have been caused by a so-called *"Segmentation violation"
>> *
>>
>> Can anyone offer any insight in these errors? I think I'm doing
>> something
>> wrong pretty early on, but have no idea what it is.
>>
>> Sincerely,
>>
>> Casper van Heck
>>
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip





More information about the fieldtrip mailing list