JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for SPM Archives


SPM Archives

SPM Archives


SPM@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

SPM Home

SPM Home

SPM  January 2014

SPM January 2014

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: Small Volume Correction, and Video Tutorial wanted

From:

"Watson, Christopher" <[log in to unmask]>

Reply-To:

Watson, Christopher

Date:

Fri, 10 Jan 2014 04:02:06 +0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (92 lines)

You can pretty much do whatever you want, as long as you have a hypothesis and it is testable. And as long as you don't, say, look at the results and pick the location that has the highest t-values.
Chris

________________________________________
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Andy Yeung [[log in to unmask]]
Sent: Thursday, January 09, 2014 10:13 PM
To: [log in to unmask]
Subject: Re: [SPM] Small Volume Correction, and Video Tutorial wanted

Dear all,

Thanks very much for all of your advice.
I have searched the literature for respective ROIs/MNI coordinates.
Is it acceptable if I just pick one ROI/VOI out of several reported from past meta-analysis?
Or do I have to apply all reported ROI/VOIs into my own SVC/ROI?
Thanks a lot.

Best,
Andy


On Fri, Jan 10, 2014 at 7:41 AM, Andy Yeung <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Dear Dr Goto,

Below is forwarded messages from SPM mailing list talking about small volume correction.
They say we have to define VOI before looking at the actual results, just like what we have discussed about.
This is by either:
1. anatomy
2. previous data
3. previous coordinates reported by other papers

We can make a mask consisting multiple VOIs.
We may perform multiple small volume correction for each contrast, but if so, we have to lower p value threshold accordingly.

Best,
Andy

---------- Forwarded message ----------
From: MCLAREN, Donald <[log in to unmask]<mailto:[log in to unmask]>>
Date: Thu, Jan 9, 2014 at 10:49 PM
Subject: Re: [SPM] Small Volume Correction, and Video Tutorial wanted
To: [log in to unmask]<mailto:[log in to unmask]>


One additional point to add to what Chris said, you should only perform SVC once per contrast. If you want to look at multiple areas, then you either need to: (1) Form a single small-volume mask that includes all the regions of interest; or (2) Divide the SVC threshold by the number of times you've performed the SVC.

Otherwise, the significance of what you find will be inflated if you repeatedly perform SVC on your data.

Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464<tel:%28773%29%20406-2464>
=====================


On Thu, Jan 9, 2014 at 7:11 AM, Christophe Phillips <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Dear Andy,

you should NOT define your SVC's based on the uncorrected results. This means, in your case, you should not simply pick a peak voxel and define a spherical volume around it for small volume FWE.
The a priori volume/location should be defined before looking at the results and independently from these, for example based on
- some anatomical priors,
- coordinates reported in the literature
- your own results from a different experience.

The size of the SVC should also be defined before hand and be representative of the prior believe about the activation location.

HTH,
Chris

Le 9/01/2014 11:57, Andy Yeung a écrit :
Dear all,

I've read SPM manual which says:

31.3.7 Small volume correction
If one has an a priori anatomical hypothesis, eg. in the present example Broca's area will likely
be activated during word generation, one may use the small volume correction option. Press the
\small volume" button in SPM Interactive (bottom left) window and select a suitable region,
e.g., a 30mm sphere with its centre at 44 16 0. The region can also be de ned using mask images
derived from previous imaging data. The corrected p-values will change, as shown in Figure 31.11.

For example if I got 4 peak voxels at 2nd level analysis, could I perform SVC 4 times separately at those peak voxels in order to report them with smaller FWE p values? If yes, how big should I set the diameter of the SVC?
Thanks very much for your time!

Yours,
Andy

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

November 2020
October 2020
September 2020
August 2020
July 2020
June 2020
May 2020
April 2020
March 2020
February 2020
January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
2006
2005
2004
2003
2002
2001
2000
1999
1998


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

For help and support help@jisc.ac.uk

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager