Re: [HCP-Users] Question about magnitude of node time series

[David Hofmann]

sorry, I meant the differences in scaling across nodes within a subject.

Thanks!

Am Do., 25. Okt. 2018 um 10:27 Uhr schrieb Steve Smith :

> Hi - do you mean differences in scaling across nodes, or within-node
> differences across subjects?
> Cheers.
>
>
> On 25 Oct 2018, at 09:21, David Hofmann  wrote:
>
> Thanks for the reply Stephen,
>
> do you have an idea, how these different amplitudes arise? Do they just
> reflect the strength of the BOLD fluctuations within these
> regions/components or are they also influenced by other factors like noise
> or something? I'm trying to understand if such differences do not arise
> purely to noise or are artifacts of some sort and have some physiological
> meaning.
>
> greetings
>
> David
>
> Am Do., 25. Okt. 2018 um 09:03 Uhr schrieb Steve Smith <
> st...@fmrib.ox.ac.uk>:
>
>> Hi -
>>
>> In the most recent PTN release, all node maps (melodic_IC.dtseries.nii)
>> created with group-ICA are sign-flipped (if necessary) to have positive
>> maximum voxel/greyordinate, and then rescaled so this peak is 1.  The
>> values of other voxels across the map will vary from node to node, and the
>> overall map determines the scaling of the node timeseries.  So yes
>> different nodes can have different amplitudes, but the scaling (for any
>> given node) is consistent across subjects.
>>
>> btw it looks like the actual stddev of those two timeseries are not
>> massively different.
>>
>> Cheers.
>>
>>
>>
>> > On 24 Oct 2018, at 23:46, David Hofmann 
>> wrote:
>> >
>> > Hi all,
>> >
>> > I was taking a look at the ICA (100) node time series and noticed that
>> some ROIs have relatively large magnitude while others have a smaller
>> magnitude (see attached pictures). Can someone explain to me how these
>> differences arise? In other words, is this the "natural" BOLD activity
>> within the ROI or does it somehow come about through the ICA and does not
>> have any meaning?
>> >
>> > Thanks in advance,
>> >
>> > David
>> > ___
>> > HCP-Users mailing list
>> > HCP-Users@humanconnectome.org
>> > http://lists.humanconnectome.org/mailman/listinfo/hcp-users
>> >
>> > 
>>
>>
>>
>> ---
>> Stephen M. Smith, Professor of Biomedical Engineering
>> Head of Analysis,  WIN (FMRIB) Oxford
>>
>> FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
>> +44 (0) 1865 610470
>> st...@fmrib.ox.ac.ukhttp://www.fmrib.ox.ac.uk/~steve
>>
>> ---
>>
>> Stop the cultural destruction of Tibet
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
> ---
> Stephen M. Smith, Professor of Biomedical Engineering
> Head of Analysis,  WIN (FMRIB) Oxford
>
> FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
> +44 (0) 1865 610470
> st...@fmrib.ox.ac.ukhttp://www.fmrib.ox.ac.uk/~steve
> ---
>
> Stop the cultural destruction of Tibet 
>
>
>
>
>
>
>
>
>

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Re: [HCP-Users] Question about magnitude of node time series

[Steve Smith]

Hi - do you mean differences in scaling across nodes, or within-node 
differences across subjects?
Cheers.


> On 25 Oct 2018, at 09:21, David Hofmann  wrote:
> 
> Thanks for the reply Stephen,
> 
> do you have an idea, how these different amplitudes arise? Do they just 
> reflect the strength of the BOLD fluctuations within these regions/components 
> or are they also influenced by other factors like noise or something? I'm 
> trying to understand if such differences do not arise purely to noise or are 
> artifacts of some sort and have some physiological meaning. 
> 
> greetings
> 
> David
> 
> Am Do., 25. Okt. 2018 um 09:03 Uhr schrieb Steve Smith  >:
> Hi - 
> 
> In the most recent PTN release, all node maps (melodic_IC.dtseries.nii) 
> created with group-ICA are sign-flipped (if necessary) to have positive 
> maximum voxel/greyordinate, and then rescaled so this peak is 1.  The values 
> of other voxels across the map will vary from node to node, and the overall 
> map determines the scaling of the node timeseries.  So yes different nodes 
> can have different amplitudes, but the scaling (for any given node) is 
> consistent across subjects.
> 
> btw it looks like the actual stddev of those two timeseries are not massively 
> different.
> 
> Cheers.
> 
> 
> 
> > On 24 Oct 2018, at 23:46, David Hofmann  > > wrote:
> > 
> > Hi all, 
> > 
> > I was taking a look at the ICA (100) node time series and noticed that some 
> > ROIs have relatively large magnitude while others have a smaller magnitude 
> > (see attached pictures). Can someone explain to me how these differences 
> > arise? In other words, is this the "natural" BOLD activity within the ROI 
> > or does it somehow come about through the ICA and does not have any meaning?
> > 
> > Thanks in advance,
> > 
> > David
> > ___
> > HCP-Users mailing list
> > HCP-Users@humanconnectome.org 
> > http://lists.humanconnectome.org/mailman/listinfo/hcp-users 
> > 
> > 
> > 
> 
> 
> ---
> Stephen M. Smith, Professor of Biomedical Engineering
> Head of Analysis,  WIN (FMRIB) Oxford
> 
> FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
> +44 (0) 1865 610470
> st...@fmrib.ox.ac.uk 
> http://www.fmrib.ox.ac.uk/~steve 
> ---
> 
> Stop the cultural destruction of Tibet
> 
> 
> 
> 
> 
> 
> 
> 
> 


---
Stephen M. Smith, Professor of Biomedical Engineering
Head of Analysis,  WIN (FMRIB) Oxford

FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
+44 (0) 1865 610470
st...@fmrib.ox.ac.ukhttp://www.fmrib.ox.ac.uk/~steve 

---

Stop the cultural destruction of Tibet 









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Re: [HCP-Users] Question about magnitude of node time series

[David Hofmann]

Thanks for the reply Stephen,

do you have an idea, how these different amplitudes arise? Do they just
reflect the strength of the BOLD fluctuations within these
regions/components or are they also influenced by other factors like noise
or something? I'm trying to understand if such differences do not arise
purely to noise or are artifacts of some sort and have some physiological
meaning.

greetings

David

Am Do., 25. Okt. 2018 um 09:03 Uhr schrieb Steve Smith :

> Hi -
>
> In the most recent PTN release, all node maps (melodic_IC.dtseries.nii)
> created with group-ICA are sign-flipped (if necessary) to have positive
> maximum voxel/greyordinate, and then rescaled so this peak is 1.  The
> values of other voxels across the map will vary from node to node, and the
> overall map determines the scaling of the node timeseries.  So yes
> different nodes can have different amplitudes, but the scaling (for any
> given node) is consistent across subjects.
>
> btw it looks like the actual stddev of those two timeseries are not
> massively different.
>
> Cheers.
>
>
>
> > On 24 Oct 2018, at 23:46, David Hofmann  wrote:
> >
> > Hi all,
> >
> > I was taking a look at the ICA (100) node time series and noticed that
> some ROIs have relatively large magnitude while others have a smaller
> magnitude (see attached pictures). Can someone explain to me how these
> differences arise? In other words, is this the "natural" BOLD activity
> within the ROI or does it somehow come about through the ICA and does not
> have any meaning?
> >
> > Thanks in advance,
> >
> > David
> > ___
> > HCP-Users mailing list
> > HCP-Users@humanconnectome.org
> > http://lists.humanconnectome.org/mailman/listinfo/hcp-users
> >
> > 
>
>
> ---
> Stephen M. Smith, Professor of Biomedical Engineering
> Head of Analysis,  WIN (FMRIB) Oxford
>
> FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
> +44 (0) 1865 610470
> st...@fmrib.ox.ac.ukhttp://www.fmrib.ox.ac.uk/~steve
> ---
>
> Stop the cultural destruction of Tibet
>
>
>
>
>
>
>
>
>

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Re: [HCP-Users] Question about magnitude of node time series

[Steve Smith]

Hi - 

In the most recent PTN release, all node maps (melodic_IC.dtseries.nii) created 
with group-ICA are sign-flipped (if necessary) to have positive maximum 
voxel/greyordinate, and then rescaled so this peak is 1.  The values of other 
voxels across the map will vary from node to node, and the overall map 
determines the scaling of the node timeseries.  So yes different nodes can have 
different amplitudes, but the scaling (for any given node) is consistent across 
subjects.

btw it looks like the actual stddev of those two timeseries are not massively 
different.

Cheers.



> On 24 Oct 2018, at 23:46, David Hofmann  wrote:
> 
> Hi all, 
> 
> I was taking a look at the ICA (100) node time series and noticed that some 
> ROIs have relatively large magnitude while others have a smaller magnitude 
> (see attached pictures). Can someone explain to me how these differences 
> arise? In other words, is this the "natural" BOLD activity within the ROI or 
> does it somehow come about through the ICA and does not have any meaning?
> 
> Thanks in advance,
> 
> David
> ___
> HCP-Users mailing list
> HCP-Users@humanconnectome.org
> http://lists.humanconnectome.org/mailman/listinfo/hcp-users
> 
> 


---
Stephen M. Smith, Professor of Biomedical Engineering
Head of Analysis,  WIN (FMRIB) Oxford

FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
+44 (0) 1865 610470
st...@fmrib.ox.ac.ukhttp://www.fmrib.ox.ac.uk/~steve
---

Stop the cultural destruction of Tibet









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[HCP-Users] Question about magnitude of node time series

[David Hofmann]

Hi all,

I was taking a look at the ICA (100) node time series and noticed that some
ROIs have relatively large magnitude while others have a smaller magnitude
(see attached pictures). Can someone explain to me how these differences
arise? In other words, is this the "natural" BOLD activity within the ROI
or does it somehow come about through the ICA and does not have any meaning?

Thanks in advance,

David

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