Are you sure that you know where your arms are right now? Body ownership is that awareness of the whereabouts of our body parts. Scientists have recently discovered new information about the way the brain works to determine body ownership.
In the 'rubber hand illusion', someone can be made to believe that a fake hand being rubbed in front of them is their own, if their own (hidden) hand is rubbed at the same time.
The common explanation to this brain trickery is that the sense of vision is combined in the brain with the sense of touch and creates stimuli which are similar to that of a real rubbing of the person's hand.
A recent experiment has proved the assumption that the visual sense is responsible for the rubber hand illusion wrong.
Dr Henrik Ehrsson and colleagues at the Wellcome Department of Imaging Neuroscience at UCL have produced similar effect with blind folded subjects.
In the new experiment, the experimenter moved the blindfolded participant's left index finger so that it touched the fake hand, and simultaneously, he touched the participant's real right hand, synchronizing the touches as perfectly as possible. After approximately 9.7 s, this stimulation elicited an illusion that one was touching one's own hand.
At the same time the brain activity of the subject was scanned using functional magnetic resonance imaging. Activity in the ventral premotor cortices, intraparietal cortices, and the cerebellum was associated with the illusion of touching one's own hand. Furthermore, the rated strength of the illusion correlated with the degree of premotor and cerebellar activity. This finding suggests that the activity in these areas reflects the detection of congruent multisensory signals from one's own body, rather than of visual representations. We propose that this could be the mechanism for the feeling of body ownership.
Sources: PubMed , Cogsci.ucsd.edu
