Researchers at the Institute of Child Health, London; Epilepsy Center, University of Edinburgh; and Dartmouth Medical School, New Hampshire, US studied memory abilities in 26 children (mean age 23 months, SD 12.6 months) after prolonged febrile seizures (median, 37.5 days), and compared to 37 normal controls. Fifteen patients were reassessed after a mean of 12.5 months. The visual paired comparison task, dependent on functional hippocampi, was used to test memory abilities. Recognition memory was impaired when tested at a median of 37.5 days following prolonged febrile seizure (> 30 min). The deficits were not related to the seizure itself or to the anticonvulsant medication. The magnitude of the decline in performance from the immediate to the delayed paradigm was linked to the size of the hippocampi at time of testing. One year later, the prolonged febrile seizure group still showed impairments in remembering a face after a 5 min delay. Age at the time of the seizure was not a factor. 
COMMENT. In this study concerning the effects of prolonged febrile seizures on recognition memory, a visual paired comparison task employing faces was used to test memory abilities in small infants. Prosopagnosia, an inability to recognize faces, is congenital and genetic or acquired. The congenital form may be inherited by ~2.5% of the population. The brain region associated with prosopagnosia is usually stated as the fusiform gyrus or an occipito-temporal location, contiguous with the hippocampal gyrus, the location emphasized in the above study. Congenital prosopagnosia is not rare. Oliver Sacks himself confused the faces of his brothers and learned that his relatives were similarly affected . A PubMed search of the literature uncovered reports of significant improvements in familiar face recognition following training of a 4-year-old child with congenital prosopagnosia . Training focused on directing visual attention to specific characteristics of the face, particularly the eye region. The performance became flawless immediately after training as well as at a follow-up assessment 1 month later. Since the visual paired comparison task uses the face in repetitive tests of memory, practice effects on an inherent prosopagnosia are a possible modifying factor in studies of the effect of prolonged febrile seizure on face recognition and memory in infants.