The neural basis of visual body perception

There is now substantial evidence from various techniques for body-selective neural mechanisms in humans and non-human primates. The neural signature of body processing generally resembles that of face processing, but there are also important differences.In the monkey inferotemporal cortex, there are different cells that respond selectively to visual images of isolated body parts, to whole bodies and to actions involving bodies. Functional MRI (fMRI) in monkeys has revealed that these cells are located near cells that respond selectively to images of faces.Intracranial and scalp measurements of electrical activity in humans have revealed body-selective waveforms that are similar to those elicited by faces, but that originate in different brain areas.fMRI studies in humans have provided evidence for two body-selective brain areas in the visual cortex: the extrastriate body area (EBA) and the fusiform body area (FBA). These areas respond selectively to (headless) bodies and body parts, even when the bodies are represented schematically. They can be dissociated from overlapping areas with high-resolution fMRI or by taking into account patterns of activation across voxels.Transcranial magnetic stimulation studies have shown that the EBA is actively involved in the successful processing of body parts but not of object parts or face parts.Some researchers have suggested that the EBA is involved in the representation of one's own body and that it contributes to the 'body schema'. However, the EBA does not distinguish between images of one's own body parts and those of others, and shows a modest preference for allocentric views of bodies and body parts.Both the EBA and the FBA are modulated by the emotional significance of body postures and body movements. This modulation is related to concurrent activation in the amygdala.The EBA can be dissociated from other brain areas involved in perceiving body actions, such as those comprising the 'mirror neuron' system. In contrast to these other areas, the EBA does not seem to be specifically involved in the representation or discrimination of body actions.