Paradoxical Prosopagnosiain Semantic Dementia

Sven-Erik Fernaeus, Per Östberg, Lars-Olof Wahlund, Nenad Bogdanovic

NEUROTEC

Karolinska Institutet

Paradoxical prosopagnosia

- When X recognize faces in one condition

but

- is unable to recognize them in another.

Example from the clinic:

A patient recognized an old schoolmate at the airport, and reported this to the examining specialist, but was unable to recognize him from photographs.

Method

Subjects: All patients diagnosed with semantic dementia 1997-98 at the memory clinic.

Five case studies.

Tests: Male Faces, Political Faces, Euro Flags

In addition to the clinical battery at Huddinge.

Results

1. Non-verbal semantic memory:

Euro Flags and Political Faces: Normal

2. Non-verbal episodic face recognition

Male Faces: SUBNORMAL (random/50%)

Comparable age group: 79.95%

Dimensions of memory1. Temporal dimension (WM, recent memory,

etc. & primacy-recency)

2. Complexity (Murdock’s item memory, associative m., serial m.) + tabular m.

3. Static vs Dynamic aspects of m.3. Static vs Dynamic aspects of m.

4. Agency

5. Linguistic vs non-linguistic aspects.

Static & dynamic aspects

1.1. Static aspects of facesStatic aspects of faces

Length, width, eye distance, etc

2. Dynamic aspects of faces2. Dynamic aspects of faces

Eye/lip movement, skin colour, other Eye/lip movement, skin colour, other emotional expressions, head movement, etc.emotional expressions, head movement, etc.

Hypothesis In Semantic Dementia atrophy of the inferior

temporal lobe blocks the stream of information from the occipital lobe to the temporal pole, to the entorhinal cortex, and other areas.

Therefore static aspects of faces in Therefore static aspects of faces in photographs do not easily give rise to photographs do not easily give rise to dynamic aspects in Semantic Dementia.dynamic aspects in Semantic Dementia.

HypothesisIn ordinary life SD-patients recognize people, In ordinary life SD-patients recognize people,

because dynamic aspects of faces are because dynamic aspects of faces are available both at presentation and ”test”.available both at presentation and ”test”.

They are also within the normal/supernormal They are also within the normal/supernormal range in tests like Political Faces, because range in tests like Political Faces, because the national political figures may have been the national political figures may have been studied in action carrying emotional studied in action carrying emotional expression, i.e. dynamic aspects.expression, i.e. dynamic aspects.