Parts of brain that help people recognize themselves identified (Re-issue)

Washington: A new study has found the answer to how we recognize our bodies as our own, distinct from others and from the outside world, a finding that may have important medical and industrial applications.

Valeria Petkova of Karolinska Institutet in Sweden and her colleagues identified the brain regions that enable people to recognize their bodies as their own, one of the most fundamental aspects of self-awareness.

The ability was traced to specialized multisensory neurons in various parts of the brain that create a unified view of the body by combining different sensory inputs from all over the body.

"When we look down at our body, we immediately experience that it belongs to us," said Petkova.

"We do not experience our body as a set of fragmented parts, but rather as a single entity. Our study is the first to tackle the important question of how we come to have the unitary experience of owning an entire body, she added.

In the new study, the researchers used a "body-swap" illusion, in which people experienced a mannequin to be their own, in combination with functional magnetic resonance imaging. Participants observed touching of the mannequin''s body from the point of view of the mannequin''s head while feeling identical synchronous touches on their own body, which they could not see.

Those studies revealed a tight coupling between the experience of full-body ownership and neural responses in brain regions known to represent multisensory processing nodes in the primate brain, specifically the bilateral ventral premotor and left intraparietal cortices and the left putamen.

Activation in those multisensory areas was stronger when the stimulated body part was attached to a body as compared with when it was detached, the researchers reported, evidence that the integrity between body segments facilitates ownership of the parts.

"Our results sug! gest tha t the integration of visual, tactile, and proprioceptive information in body-part-centered reference frames represents a basic neural mechanism underlying the feeling of ownership of entire bodies," added the researchers.



The study has been reported online in Current Biology, a Cell Press publication.