After damage or anaesthetisation of the right brain hemisphere, some people can suffer from misidentification of their own extremities (a condition known as asomatopagnosia). Researchers from Harvard Medical School believe they now have the data to explain why this happens.

Julian Paul Keenan and colleagues studied patients who were having their brain hemispheres individually anaesthetised to investigate their epilepsy. During anaesthesia, the patients were shown pictures of faces generated by morphing the picture of a famous person with the patient's own face. After anaesthesia the patients were asked whether they had been presented with a picture of their own face or that of a famous person. When the left hemisphere was anaesthetised, the patients recognised their own face as the one presented; after anaesthesia of the right hemisphere they only recognised the famous face (Nature 2001, 409:305).

There was also a significant activity in the right hemispheres of healthy controls seeing pictures containing elements of their own faces. The authors therefore suggest that a right-hemisphere network gives rise to self awareness, which may be a hallmark of higher-order consciousness.