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: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=18960 or send a blank email to leave-18960-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
