[Mne_analysis] Query over medial wall activity

dgw dgwakeman at gmail.com
Wed Feb 6 17:29:17 EST 2013
Search archives:

Generally, I am dubious about the likelihood of there being sufficient
pyramidal dendrites in these regions to provide the necessary
architecture for generating signal. I have considered removing these
locations from my forward solution. I am also curious about others'
thoughts.

D

On Wed, Feb 6, 2013 at 5:01 PM, A.C.G. Thwaites <acgt2 at cam.ac.uk> wrote:
> Hi MNE-ers
>
>
> I am working with auditory data, running my analysis on source estimations
> reconstructed from MEG and EEG sensor recordings.
>
>
> My analysis takes the form of pattern matching over the estimated activity
> of each of the vertices in a source space, and as such, is reliant on the
> reconstruction being of good quality. I am very pleased with the quality
> of the results using MNE - my pattern matching technique should locate
> those vertices along Heshl's Gyrus, and indeed it does - an indication,
> presumably, of the high quality of the reconstruction. (so a big thank you
> to everybody involved with constructing and maintaining MNE!)
>
>
> However, I did want to ask this mailing list about one concern: my pattern
> matching technique also picks up vertices directly 'under' HG - on the
> medial wall in the 'unknown' label of the Destrieux Atlas
> (aparc.a2009s.annot) (see figure 1 attached). It seems pretty clear why:
> the inverse solutions given by MNE give both these regions similar evoked
> responses (figure 2 of the attached), which is why my pattern matching
> technique flags both areas up. While it is possible that these results may
> be correct (the auditory thalamus is in this area, and so might plausibly
> causing this medial activity) I wanted to poll this mailing list to get a
> feel for how likely you think this activity is being correctly estimated
> here, or if you feel it is a simple case of mislocalisation from the
> auditory cortex (and if so, whether it can be fixed). I'm not really sure
> what my grounds for suspicion are, except that the affected vertices on
> the medial wall are directly under HG - implying the HG source activity
> might be 'seeping' through to these more medial sources during
> reconstruction.
>
> I have observed this phenomenon in two independent experiments. And
> although I can't do my pattern matching on the MNE example 'audvis' data,
> this too seems to show the same phenomenon (figure 3).
>
>
> I have tried pretty much every flag and option MNE offers - depth on/off,
> sLORETA vs. MNE vs. DSPM, different SNRs, pick_normal on/off, different
> looseness's - all end up with pretty much identical results (which is
> good, I guess, as it means the reconstruction is pretty robust).
>
>
> I appreciate that for many people this isn't an issue if they are doing
> analysis only in predetermined regions of interest (I can't imagine that
> many people are looking for results in a label called 'unknown'). But as
> my analysis works by searching vertex-by-vertex, I want to say truthfully
> that I looked through all vertices the reconstruction gave back, or at
> least give a reason why I excluded vertices in the `unknown' label from my
> analysis.
>
>
> Anyway, I don't know if it is a common occurrence, or is something I have
> done wrong (although the fact that we see the 'audvis' data behave in the
> same way is evidence against this). Or maybe you think it is correct - a
> number of my co-authors have suggested we take it as correct, and say it
> is evidence of a cortico-Thalamic loop.
>
> I attach some figures that demonstrate the phenomenon.
>
>
> Thanks in advance for any thoughts.
>
>
> Andy
>
>
>
> _______________________________________________
> Mne_analysis mailing list
> Mne_analysis at nmr.mgh.harvard.edu
> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis
>
>
> The information in this e-mail is intended only for the person to whom it is
> addressed. If you believe this e-mail was sent to you in error and the
> e-mail
> contains patient information, please contact the Partners Compliance
> HelpLine at
> http://www.partners.org/complianceline . If the e-mail was sent to you in
> error
> but does not contain patient information, please contact the sender and
> properly
> dispose of the e-mail.
>



More information about the Mne_analysis mailing list