G/WEDS/PAN1 EVIDENCE FOR A LACK OF EARLY STRUCTURAL FACIAL ENCODING IN A CHILD WITH PROSOPAGNOSIA ACQUIRED IN INFANCY

A. Basu¹, T. Kelly², N. Greening¹, S. Mafeld¹, J. Eyre¹.¹Child Health, University of Newcastle upon Tyne, Newcastle, UK; ²Neuropsychology Department, Newcastle General Hospital, Newcastle, UK

Introduction: Prosopagnosia is impaired or absent face recognition despite normal visual processing of other objects. In healthy adults and children, face recognition evokes an early EEG potential, the N170, which is characteristically greater in amplitude to inverted faces and reflects early structural encoding of faces. Our aim was to determine whether a child with prosopagnosia had evidence of early facial encoding and might therefore be able to be taught to recognise faces.

Methods: The subject (RC; female, 13 years) who was of normal intelligence, had focal damage to the occipital and temporal lobes from herpes simplex encephalitis, age 11 months. Control subjects were 10 young adults and 3 children aged 7, 9 and 12 years. RC had standardised neuropsychological assessments of visual processing. EEG was recorded from all subjects while they viewed 64 randomly ordered, sex-matched, presentations of their own face, famous persons’ faces and unknown faces, either in upright or inverted orientations. A control image of a black square was also presented. The amplitude and latency of the N170 were compared (1) using averaged event related potentials and an ANOVA for adults (2) using independent component analysis and a z-test for all subjects.

Results:Neuropsychological testing: RC demonstrated normal object recognition despite some object naming difficulties. There was no evidence of facial recognition. EEG: There was no difference between RC and normal subjects for the potentials evoked by the control stimulus. All normal subjects demonstrated an N170 to faces, which was larger (p<0.001) and delayed (p = 0.004) to face inversion, but not affected by face familiarity. RC did not demonstrate …