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I watched last night's episode of 60 minutes about Prosopagnosia (Face Blindness) and found it absolutely fascinating. They mentioned in the segment (Around 5:22 into the second part of the online video) that Nancy Kanwisher of MIT has studied the MRI scans of people without Prosopagnosia and found that the fusiform face area lit up on an MRI when an individual was shown an image of a face.

Nancy Kanwisher then goes on to state the following:

I really did not expect to see a fusiform face area [on an MRI scan of a patient with Prosopagnosia]. [...] And we looked at the data and his face area was beautiful, it was textbook. [...] It tells us that the problem is not that this thing [(the fusiform face area)] does not exist, there it is!

Image of a MRI scan of a patient with Prosopagnosia

The image shows an MRI scan of a patient who has Prosopagnosia, demonstrating that the patient does have a fusiform face area. However it was unclear to me whether the fusiform face area of an individual suffering from Prosopagnosia is less active when presented with a face than that of an individual without Prosopagnosia. What did Nancy Kanwisher find with regards to that? Does the fusiform face area in individuals with Prosopagnosia exist but remains dormant? Or is it just as active but for some other (probably unknown) reason simply fail to relay the proper information to the rest of the brain?

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I'm not really loving the brain-injury tag @BenBrocka... I guess it fits given that the tag covers congenital disorders, but it doesn't feel right to me... –  Josh Gitlin Sep 13 '12 at 1:45
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It is not widely thought that impaired function or destruction of the fusiform is sufficient to produce prosoganosia. It is currently widely held that face processing involves a network of regions in the occipital and temporal lobes (e.g., the occipital face area, posterior superior temporal sulus, anterior superior temporal sulus, anterior collateral sulcus). For example, Bruno Rossion reports a patient with prosopagnoisa who has widespread damage to bilateral occipital and temporal brain regions but with a spared right FFA. Moreover, work by Marlene Behrmann has shown that people with developmental prosopagnosia have disrupted connections between the posterior temporal lobes (ie near the FFA) and the anterior temporal lobes. This is significant because there is growing evidence that there may be face selective regions in the anterior temporal lobes and that they are more directly involved in face recognition. Moreover there is some evidence that this anterior temporal region modulates the activity in the FFA (Nestor, Plaut, Behrmann, 2011 PNAS). So it might very well be that the FFA does show decreased activity in a face recognition task, but this might be due to impaired feedback to this region. On this view, lower activity in FFA is the effect of prosopagnosia not the cause, so making comparisons on levels of activity within one region might not be as meaningful as you think.

References

  • Nestor, A., Plaut, D.C., & Behrmann, M. (2011). Unraveling the distributed neural code of facial identity through spatiotemporal pattern analysis. Proceedings of the National Academy of Sciences, 108, 9998. LINK
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Yes, though not necessarily in the way that you are meaning - some prosopagnosics will have damage to the area in question, so you could say the activity is lower because there is not much left of it!

Quick google reveals this paper: http://cercor.oxfordjournals.org/content/20/8/1878.abstract

It's recent so will probably review the evidence you are interested in.

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Please forgive me for being an idiot, but I'm not understanding what that article is saying. Specifically: These results reveal that fusiform activation is still selectively modulated by task demands related to the anticipation of a face, despite severe face-recognition deficits and the fact that no reliable stimulus-driven response is evoked by actual facial information. Does that mean the fusiform area activates even when the patient expects faces but sees only noise? So it activates at the wrong time? –  Josh Gitlin Mar 23 '12 at 17:08
    
@JoshGitlin if you have a specific question about a specific part of a paper maybe you should ask it as a whole new question :D –  Artem Kaznatcheev Apr 29 '12 at 7:34
    
Josh, it was randomly selected so not meant to be indicative of anything in particular! –  vizzero May 30 '12 at 18:50
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