Case 8- The Man who Mistook His Wife for a Hat Flashcards
Prosopagnosia:
Prosopagnosia is a neurological condition characterized by the inability to recognize familiar faces. There are two main types: acquired prosopagnosia (AP) and developmental prosopagnosia (DP). AP is caused by neurological injury or illness, resulting in severe impairment in recognizing faces, often triggering recognition through alternative means. DP, on the other hand, is a lifelong face recognition impairment without neurological damage.
Acquired Prosopagnosia (AP):
Definition: Inability to recognize familiar faces due to neurological injury.
Prevalence: Rare, especially in its pure form.
Aetiology: Can result from bilateral or unilateral lesions, with co-morbid visual impairments common.
Types: Apperceptive (structural encoding issues) and Associative (linking percept to stored representations) prosopagnosia.
Deficits: Impaired face recognition, but other visual and cognitive functions may remain normal.
Case Studies: DC (Apperceptive prosopagnosic) and PH (Associative prosopagnosic).
Developmental Prosopagnosia (DP):
Definition: Lifelong face recognition impairment without neurological damage.
Face-Specificity: Varies among individuals, with some having broader deficits in within-class discriminations or other face processing aspects.
Associated Difficulties: Navigational issues, speech-reading problems, and deficits confined to face recognition in some cases.
Case Study: First case published in 1976 - AB, a 12-year-old girl with face recognition difficulties.
Testing for Prosopagnosia:
Face Identification: Recognizing famous faces or determining whether faces are famous in a mix of famous and non-famous faces.
Face Matching: Deciding if two faces are different or two views of the same face.
Issues in Face Recognition Tests:
Recognition might be possible through non-facial cues or specific facial features.
Unlimited time allows laborious cross-checking, potentially masking the severity of the impairment.
Causes of Developmental Prosopagnosia (DP):
Genetic Factors:
Autosomal dominant transmission, with evidence suggesting a genetic component.
Varying prevalence in families, with a ratio of non-hereditary to hereditary cases.
Some individuals with DP show symptoms on the autistic spectrum, indicating a potential link between DP and autism.
Debate exists on the causal relationship, with some proposing early amygdala dysfunction as a factor.
DP might occur independently of socio-developmental disorders.
Early Visual Problems:
Severe myopia or cataracts in early life might contribute to DP (Le Grand et al., 2001; Le Grand, Mondloch, Maurer, and Brent, 2003).
Early Brain Damage:
Avidan et al. (2008) demonstrated perceptual impairment, challenging the notion of impaired memory for names alone.
Case Studies:
TA (Jones and Tranel, 2001):
5-year-old associative DP with navigational difficulties but normal perception and emotional expression.
Above-average skills in visual naming, reading, spelling, arithmetic, and high IQ.
Poor overt recognition but normal covert recognition (skin conductance).
Case Studies:
Hereditary DPs (Gruter, Gruter, and Carbon, 2008):
Uncertainty about face familiarity, longer recognition times, abnormal eye-gaze patterns, and occasional impairment in object and scene perception.
No deficits in emotional perception, judgments of attractiveness, or gender recognition.
Neural Correlates of DP:
Formal fusiform gyrus (FG) activity in DPs, but not in all cases.
Avidan et al. (2008) reported reduced connectivity between FG and other brain regions in DPs.
Altered inferior longitudinal fasciculus and inferior fronto-occipital fasicilus in DPs.
Case Study: Edward (Duchaine, Yovel, Butterworth, and Nakayama, 2006):
Lifelong face recognition difficulties with expression perception problems.
No navigational difficulties, no inversion effect, normal contrast sensitivity, BORB, and naming of line drawings.
Specific issues with face recognition and emotion recognition.
Deficit at the structural encoding stage of face processing, possibly due to a lack of face-specific processing mechanisms.
Biotti et al. (2017):
Significant composite effect in the DP group.
Composite effect magnitude similar to normal face processing participants.
Not impaired at configural processing, suggesting deficits in structural encoding.
Developmental Prosopagnosia Summary:
Possible genetic etiology with a link to other socio-developmental disorders.
Associated deficits in configural processing.
Fusiform gyrus activation is necessary but not sufficient for normal face processing.
Consideration of DP as part of a continuum of ‘normal’ face recognition, with super-recognizers at the other end.
FFA Function:
Activated by various face stimuli but not sufficient or essential for face recognition.
Inconsistent findings on FFA’s differential response to familiar/unfamiliar faces.
Left anterior middle temporal gyrus and temporal pole may play a more direct role in recognition and memory processes.
