I watched last night's episode of 60 minutes (and part 2) 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!
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?