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Dear Freesurfers
Usually, the mean normalized intensity in aseg.stats is not considered important. However, by mistake, I put it in my analysis and found out that the mean intensity of the thalamus explains a lot the variance of my data.
What could be the physiological meaning of higher intensity in the thalamus? Could it be associated with either increased myelinization ( more axons or synapses) or with decreased neural soma? Has anybody reported mean normalized intensity effects in subcortical structures?
Thanks Dorothy
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What is the other variable?
Matt.
From: <freesurfer-bounces@nmr.mgh.harvard.edumailto:freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Dorothy Sincasto <dsincasto@gmail.commailto:dsincasto@gmail.com> Reply-To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Date: Thursday, March 21, 2019 at 8:44 PM To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Subject: [Freesurfer] Gray matter normalized intensity
External Email - Use Caution
Dear Freesurfers
Usually, the mean normalized intensity in aseg.stats is not considered important. However, by mistake, I put it in my analysis and found out that the mean intensity of the thalamus explains a lot the variance of my data.
What could be the physiological meaning of higher intensity in the thalamus? Could it be associated with either increased myelinization ( more axons or synapses) or with decreased neural soma? Has anybody reported mean normalized intensity effects in subcortical structures?
Thanks Dorothy
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Hi Matt
The other variable is cortical power. Actually, we found that the ratio of thalamic mean intensity with normalized cortical gray matter volume is associated with cortical power. I was going to discard it but theoretically, it made sense, to take out the contribution of cortical gray matter and just leave the level of thalamic myelinization.
Regards Dorothy
On Thu, Mar 21, 2019 at 6:48 PM Glasser, Matthew glasserm@wustl.edu wrote:
External Email - Use CautionWhat is the other variable?
Matt.
From: freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Dorothy Sincasto dsincasto@gmail.com Reply-To: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Date: Thursday, March 21, 2019 at 8:44 PM To: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] Gray matter normalized intensity
External Email - Use CautionDear Freesurfers
Usually, the mean normalized intensity in aseg.stats is not considered important. However, by mistake, I put it in my analysis and found out that the mean intensity of the thalamus explains a lot the variance of my data.
What could be the physiological meaning of higher intensity in the thalamus? Could it be associated with either increased myelinization ( more axons or synapses) or with decreased neural soma? Has anybody reported mean normalized intensity effects in subcortical structures?
Thanks Dorothy
The materials in this message are private and may contain Protected Healthcare Information or other information of a sensitive nature. If you are not the intended recipient, be advised that any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error, please immediately notify the sender via telephone or return mail. _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Hi Dorothy
yes, we have looked at intensity effects in the gray matter before (David Salat for example has done this). It certainly reflects degree of myelination as well as other things. Which volume are you looking at? The norm should be ok for this
cheers Bruce On Thu, 21 Mar 2019, Dorothy Sincasto wrote:
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Dear Freesurfers Usually, the mean normalized intensity in aseg.stats is not considered important. However, by mistake, I put it in my analysis and found out that the mean intensity of the thalamus explains a lot the variance of my data.
What could be the physiological meaning of higher intensity in the thalamus? Could it be associated with either increased myelinization ( more axons or synapses) or with decreased neural soma? Has anybody reported mean normalized intensity effects in subcortical structures?
Thanks Dorothy
The intensity is partially what VBM is picking up, so it is not at all unreasonable to look at.
On 3/21/19 9:52 PM, Bruce Fischl wrote: Hi Dorothy
yes, we have looked at intensity effects in the gray matter before (David Salat for example has done this). It certainly reflects degree of myelination as well as other things. Which volume are you looking at? The norm should be ok for this
cheers Bruce On Thu, 21 Mar 2019, Dorothy Sincasto wrote:
External Email - Use Caution
Dear Freesurfers Usually, the mean normalized intensity in aseg.stats is not considered important. However, by mistake, I put it in my analysis and found out that the mean intensity of the thalamus explains a lot the variance of my data.
What could be the physiological meaning of higher intensity in the thalamus? Could it be associated with either increased myelinization ( more axons or synapses) or with decreased neural soma? Has anybody reported mean normalized intensity effects in subcortical structures?
Thanks Dorothy
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