Re:[tips] Some Problems with Neuroimaging
I used to have many of the blog author's reservations until I began to use fMRI in clinical cases and verifying basic brain functions. As long as you are not looking for the God Center, or verifying some crackpot cognitive theory, the results are reliable and valid. This surprised me since I expected more uncertainty and error. Most psychological tests do not have the reliability of fMRI. I know that sounds odd. The examples given by the blogger suggest a lot of statistical error, at least at the level of the usual cognitive test. However, if I administer a simple cognitive task, such as naming pictures, the fMRI analysis will show the same results every time. The left image shows the results of an fMRI study of a patient with a meningioma in the left parietal-temporal area: http://www.learnpsychology.com/neuropsych/images/tumors.jpg The Naming task is associated with BOLD responses in the occipital lobes and the language centers in the left hemisphere. Notice that the language activation actually outlines the margins of the tumor. The patient's language was normal. Knowing that language centers are under the tumor is extremely important in surgery planning. The image on the right shows a tumor in the right temporal lobe that is interrupting vision pathways connecting the Lateral Geniculate Body to the Occipital Lobe. Notice that the left Occipital Lobe is active but the right Occipital Lobe is inactive. The patient had a very clear loss of vision in the upper left quadrant of the visual field. The problems with fMRI that I endorse have nothing to do with the method itself. The fMRI method is continuing to be developed and its underlying evolution is proceeding well. New MRI scanners that can handle the data and give radiologists a turn-key technology for fMRI are available now. New connectivity modeling and other data analysis procedures are also moving fMRI along. If you come into the hospital today with a brain tumor, it is likely that you will get an fMRI study while you are in the MRI scanner getting your structural scans. The problems are all the result of people jumping on the bandwagon and trying to scoop the next sensational finding. This is actually hurting the method. We need to conduct the usual reliability and validity studies that psychologists are well known for in the development of new methods. Unfortunately, I don't think human brain function is as interesting as cognitive psychologists think it is. Most cognitive psychologists don't know enough about brain function to draw correct inferences. After you consider all the tissue mediating simple neurological and cognitive functions, there is not much left for all the complex cognitive abilities cognitive psychologists believe are there. When they conduct research that does not have explicit hypotheses connecting a cognitive ability or construct to specific functional brain systems, they can show any activation pattern and proclaim that the whatsy center has been discovered. Most activation patterns are not the result of error suggested by the blogger. They are usually the result of activation associated with the task that were not accounted for by the theory underlying the task. For example, many language tasks will activate language areas that are not the focus of a particular cognitive neuroscience language study. If the investigator is unaware of these then they will appear as false positive errors. I was also involved in one of the fMRI deception studies. Here, fMRI may actually pan out as a lie detector. Lies involve a simple inhibition of the truth and a construction of an alternate response. The truth just comes out. The former requires much more frontal lobe inhibition than telling the truth. We worked with an excellent polygrapher who educated me on many things about polygraphs and ways to study and detect lies. The first was that polygraphs are not designed to detect lies; they are designed to elicit confessions. That is why they are in widespread use by police departments but not admitted into courts. Here is a great video segment I use in presentations: http://www.learnpsychology.com/fmri/jerrypolysm.mov Mohamed FB, Faro SH, Gordon NJ, Platek SM, Ahmad H, Williams M. (2006). Brain mapping of deception and truth telling about an ecologically valid situation:An fMRI and polygraph investigation-initial experience./Radiology/, 238: 679-688. Mike Williams --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5n=Tl=tipso=18960 or send a blank email to leave-18960-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
RE: Re:[tips] Some Problems with Neuroimaging
Only offering this as a cautionary tale (but not taking sides because others know far more about this than I), and because it's damned funny. http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf I always use this in my methods and cognitive classes to make sure that students don't jump to conclusions. And they get a big laugh out of it, as I did. m -- Marc Carter, PhD Associate Professor of Psychology Chair, Department of Behavioral and Health Sciences College of Arts Sciences Baker University -- The information contained in this e-mail and any attachments thereto (e-mail) is sent by Baker University (BU) and is intended to be confidential and for the use of only the individual or entity named above. The information may be protected by federal and state privacy and disclosures acts or other legal rules. If the reader of this message is not the intended recipient, you are notified that retention, dissemination, distribution or copying of this e-mail is strictly prohibited. If you have received this e-mail in error please immediately notify Baker University by email reply and immediately and permanently delete this e-mail message and any attachments thereto. Thank you. --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5n=Tl=tipso=18963 or send a blank email to leave-18963-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
Re: [tips] Some Problems with Neuroimaging
On Jul 11, 2012, at 5:13 PM, Jeffry Ricker, PhD wrote: I don't think the authors meant it as a cautionary tale. According to Craig Bennett, the first author of the Salmon Study: The goal of the Salmon poster was to encourage the minority of researchers who report uncorrected statistics to move forward and begin using basic multiple comparisons correction in their research. The Salmon doesn’t add anything to the technical discussion of how multiple comparisons correction is performed, it is simply a salient reminder of why proper correction is always necessary. (http://prefrontal.org/blog/2009/09/the-internet-found-the-atlantic-salmon/) Best, Jeff -- - Jeffry Ricker, Ph.D. SCC: Professor of Psychology MCCCD: General Studies Faculty Representative PSY 101 Website: http://sccpsy101.wordpress.com/ - Scottsdale Community College 9000 E. Chaparral Road Scottsdale, AZ 85256-2626 Office: SB-123 Phone: (480) 423-6213 Fax: (480) 423-6298 --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5n=Tl=tipso=18968 or send a blank email to leave-18968-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
Re: [tips] Some Problems with Neuroimaging
For those who are interested in reading the Margulies chapter that Jeff cites below, most of if is accessible on books.google.com at: http://books.google.com/books?hl=enlr=id=qp1NUVdlcZACoi=fndpg=PA273dq=Margulies,+D.+S.+%282011%29+The+salmon+of+doubt:+Six+months+of+methodological++controversy+within+social+neuroscience.+ots=FfQRwOrz7asig=yrKiZWtkxyQPjDeGxA1nn6piFGo#v=onepageqf=false However, it is not clear from this source whether the correct correction was applied or not. The issue is comparable to that of multiple comparison testing after a significant F in an ANOVA (NOTE: I assume that the corrections were planned before the data was collected and not after one has looked at the data or that one is engaged in unplanned comparisons). The Bonferroni correction is one way to do it but there are others; see, for example, the following: http://jeb.sagepub.com/content/5/3/269.short Now, I'm not familiar with what kind of voodoo, er, I mean, statistical rituals they follow in analyzing neuroimaging data, whether they test for homogeneity of variance, sphericity, or other conditions necessary the validity of the statistical tests they do. I see no argument provided for why the Bonferroni procedure was used instead of other procedures, such as: http://biomet.oxfordjournals.org/content/73/3/751.short or Multiple Comparison Methods for MeansAuthor(s): John A. Rafter, Martha L. Abell and James P. Braselton Source: SIAM Review, Vol. 44, No. 2 (Jun., 2002), pp. 259-278 Published by: Society for Industrial and Applied Mathematics Stable URL: http://www.jstor.org/stable/4148355 . NOTE: This presentation assumes that the means are independent; within-subject designs produced correlated results and complicate things. So, when it comes to correcting for the number of tests one is doing, there's more than one way to skin a cat or prepare a salmon. And let's not even get started on the reduction of power in making the correction. -Mike Palij New York University m...@nyu.edu -- Original Message -- On Wed, 11 Jul 2012 17:13:41 -0700, Jeffry Ricker, PhD wrote: On Jul 11, 2012, at 6:33 AM, Marc Carter wrote: Only offering this as a cautionary tale (but not taking sides because others know far more about this than I), and because it's damned funny. http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf I always use this in my methods and cognitive classes to make sure that students don't jump to conclusions. And they get a big laugh out of it, as I did. I don't think the authors meant it as a cautionary tale. According to Margulies (2011), the poster was intended to be a light-hearted demonstration that the statistical corrections typically used by social-neuroscience researchers are generally adequate for validly interpreting fMRI results: Before proper correction for multiple comparisons, a cluster 27 mm3 was found to be significant within the brain cavity; however, the authors dutifully noted that “due to the coarse resolution of the echo-planar image acquisition and the relatively small size of the salmon brain further discrimination between brain regions could not be completed” (Bennett et al., 2009). Of course (and thankfully), after proper statistical correction, no active voxels were detected. (emphasis added, p. 282) Margulies continued: To those unfamiliar with the techniques, this appeared to be another successful attack against social neuroscience However, those within the community understood that the obvious tongue-in-cheek presentation was far from being an attempt to invalidate fMRI approaches to questions of social cognition. Rather, it was an example of statistical criticism, which reinforced the validity of correction techniques that have long been argued as essential. (pp. 282-283) Best, Jeff Margulies, D. S. (2011) The salmon of doubt: Six months of methodological controversy within social neuroscience. In S. Choudhury J. Slaby (Eds.), Critical Neuroscience: A Handbook of the Social and Cultural Contexts of Neuroscience (pp. 273-285). London: Wiley-Blackwell. doi: 10.1002/9781444343359.ch13 --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5n=Tl=tipso=18969 or send a blank email to leave-18969-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
