The Occipitotemporal Network for Face and Object Recognition: Prosopagnosia and Object Agnosia Perceptual information about faces and objects is initially encoded in primary (striate) visual cortex and adjacent (upstream) peristriate visual association areas. This information is subsequently relayed first to the downstream visual association areas of occipitotemporal cortex and then to other heteromodal and paralimbic areas of the cerebral cortex. Bilateral lesions in the fusiform and lingual gyri of the occipitotemporal cortex disrupt this process and interfere with the ability of otherwise intact perceptual information to activate the distributed multimodal associations that lead to the recognition of faces and. | Chapter 027. Aphasia Memory Loss and Other Focal Cerebral Disorders Part 11 The Occipitotemporal Network for Face and Object Recognition Prosopagnosia and Object Agnosia Perceptual information about faces and objects is initially encoded in primary striate visual cortex and adjacent upstream peristriate visual association areas. This information is subsequently relayed first to the downstream visual association areas of occipitotemporal cortex and then to other heteromodal and paralimbic areas of the cerebral cortex. Bilateral lesions in the fusiform and lingual gyri of the occipitotemporal cortex disrupt this process and interfere with the ability of otherwise intact perceptual information to activate the distributed multimodal associations that lead to the recognition of faces and objects. The resultant face and object recognition deficits are known as prosopagnosia and visual object agnosia. The patient with prosopagnosia cannot recognize familiar faces including sometimes the reflection of his or her own face in the mirror. This is not a perceptual deficit since prosopagnosic patients can easily tell if two faces are identical or not. Furthermore a prosopagnosic patient who cannot recognize a familiar face by visual inspection alone can use auditory cues to reach appropriate recognition if allowed to listen to the person s voice. The deficit in prosopagnosia is therefore modality-specific and reflects the existence of a lesion that prevents the activation of otherwise intact multimodal templates by relevant visual input. Damasio has pointed out that the deficit in prosopagnosia is not limited to the recognition of faces but that it can also extend to the recognition of individual members of larger generic object groups. For example prosopagnosic patients characteristically have no difficulty with the generic identification of a face as a face or of a car as a car but they cannot recognize the identity of an individual face or the make of an individual car. This
