Basi nervose dell'agnosia per le parti corporee e le azioni umane

Visual analysis of faces and non-facial body stimuli brings about neural activity in different cortical areas. Moreover, even if inherently linked, body form and body action may be represented in separate neural substrates. Brain lesion studies show specific face processing deficits but neuropsychological evidence for defective recognition of non-facial body parts is lacking. Combining psychophysics and lesionmapping techniques we found that brain lesions specifically affecting the ventromedial and lateral occipital cortex induce visual recognition deficits of face and nonfacial body parts respectively. Moreover, we discovered recognition impairments specifically affecting the form or the action of non-facial body stimuli and causatively associated with lesions to occipito-temporal and premotor areas respectively. These category-specific deficits, called body form and body action agnosia, suggest that visual processing of non-facial body parts is based on a cortical division of labour with occipito-temporal areas actively linked to processing body identity and premotor areas to processing body action independent from the actors’ identity.