What and where in the processing of body-part information
Our brain tells us where parts of the body are in space. We know
without looking if our arm is in the air, our foot is in front of the
other or beside it. It is called proprioception or body localization and
helps us locate our body parts.
We also know that our foot/hand/tongue is part of us and that we have control of it because it can be sensed or felt.
Until now, it has been assumed that the perceived location of one’s
body part can be used as a behavioral measure to assess the feeling of
owning a body part. This means that the experience of where one’s body
parts are perceived to be located in space (body localization) and the
experience of identifying with the body parts (body ownership) depend on
the same process in the brain.
Body awareness – Our brain integrates visual, tactile and proprioceptive
information to know that seen body parts are part of our own body.
© Kazumichi Matsumiya)
However, Kazumichi Matsumiya, a researcher at Tohoku University in
Japan has identified that there are in fact two processes underlying
To investigate whether the processing pathway is shared between body
localization and body ownership, Matsumiya used a computational model of
multisensory integration processes and applied this model to a
perceptual illusion in which ownership over an artificial hand is
He found that variances predicted by the model are similar to those
observed in localization of the participant’s hand, but systematically
diverge from those observed in ownership of the artificial hand. These
findings provide strong evidence for separate processes between
ownership and localization of body parts, and indicate a need to revise
current models of body part ownership.
The present finding – Initial work assumed that the perceived location
of one’s body part can be used as a behavioral measure to assess the
feeling of owning a body part. However, the present results reveal
separate processes between ownership and localization of body parts.
© Kazumichi Matsumiya)
Results from this study suggest that the neural substrates for
perceptual identification of one’s body parts–such as body
ownership–are distinct from those underlying spatial localization of
the body parts, thus implying a functional distinction between “what”
and “where” in the processing of body part information.
These findings may have implications for understanding the underlying
mechanisms for body self-awareness that play an important role in
rehabilitation to overcome motor dysfunctions.