Case Study - PS Flashcards
What diagnosis was she given?
Pure apperceptive prosopagnosia
Can recognise objects perfectly but not faces at all
Who studies PS ?
Rossion et al (2003)
What are the locations of her lesions?
Bilateral occipitotemporal lesions
The right occipital face area was damaged BUT the right FFA was spared
What functions are Impaired?
Cannot process faces - uses things like haircut and voice
Struggles with any fine grain visual tasks, like counting dots
Processing speed measured through reaction times are slightly slower
(But this is normal for brain damaged patients Benton 1986)
What function was spared?
Motor abilities Language was unimpaired Calculation Imagery Memory Object recognition Visual acuity
What tasks did they use to test PS?
Shown 60 faces and unfamiliar faces and asked to categorise
Could correctly identify all the unfamiliar ones but said only 14/60 were recognisable to her
When asked to name the 14 she recognised she could only name 4
Scores were severely impaired in bentons face recognition task and warringtons
When shown images of activations in PS’s brain what can you see that is different in the ,eat and right hemispheres ?
There is a large activation In the face processing areas, because lesions are anterior to these areas
But in the left hemisphere the lesions destroyed this area
What does the lesions that PS has say about where the brain processes objects?
PS doesn’t have impaired object recognition even though she has extensive lesions to the medial temporal lobe .
So it suggests object recognition must not be localised to one specific area but a lot of different areas.
What other piece of evidence suggests that object processing must happen in quite a large area of the brain? Rather than a small localised portion of the medial temporal?
Only patients with extensive bilateral lesioning of the ventral temporal and the medial occipital pathways show deficits
What was the original belief about the rFFA?
How does PS disprove this?
rFFA was originally thought to be responsible for face processing however PS has a complete one and still can’t recognise faces
PS has damage to her lFFA but why is it unlikely that it is this left hemisphere damage that is causing her prosopagnosia?
Patients with only unilateral damage to the rFFA have been found with prosopagnosia.
So what conclusion can you draw about why PS has prosopagnosia ? Which specific lesions area?
Which researcher also found this result?
PS is missing the right occipital face sensitive area or rOFA , which is thought to process the individual elements of the face which is then sent on to the FFA to finalise a composite. Thus having a whole FFA isn’t useful without a rOFA to support it.
Haxby (2000)
What did hubel & Wiesel (1977) propose?
A feedforward system where information starts at the posterior parts of the brain and as it is processed more it moves to the more anterior parts of the brain with the larger receptive fields
Who contested haxby (2000) ideas about the rOFA and rFFA?
Tenaka showed that we process faces as a whole rather than individual features, so then what is the job of the rOFA? And there is also still activation in the FFA when the rOFA is offline
How did rossion settle the debate about the rOFA and the rFFA?
Rossion suggested that there was a dynamic relationship between the two which is why there is still activation in the FFA but detailed face processing and recognition can’t occur without both elements being present. And that this idea could only be confirmed through more detailed imaging.
