New research reveals that people's brains can easily be tricked into thinking that an artificial finger is their own, providing insight into how the brain processes body representation, ScienceDaily reports.
Researchers had participants hold an artifical finger with their left hand 12 cm above their right index finger, their vision eliminated and their skin numbed with anaesthesia. When both the right index finger and articial finger were moved at the same time, subjects incorrectly reported that they were holding their own left finger, the brain incorporating the artifical finger into its body representation.
"It may seem silly to ask yourself whether your index finger is part of your body. However, our current findings demonstrate that this question has led to important insights into key brain functions," Professor Simon Gandevia, Deputy Director of Neuroscience Research Australia (NeuRA), said in a statement. "These findings could lead to new clinical interventions where the addition or the removal of specific sensory stimuli is used to change someone's body image."
Contrary to previous theories that the brain requires multiple sensory signals such as touch and vision to create body representation, the latest study demonstrates that messages from muscle receptors are enough for the brain.
"This illusion demonstrates that our brain is a thoughtful (yet at times gullible!) decision maker: it uses available sensory information and memories of past experiences to decide what scenario is most likely (i.e. 'my hands are level')," Gandevia said.
In addition, the research team discovered a new sensory illusion known as the "grasp illusion," in which the perceived "distances between index fingers decreases when subjects hold an artificial finger."
Researchers hope that their latest discoveries will help provide insight into where body representation in the brain is disrupted when people suffer from disorders such as schizophrenia, stroke and phantom limb syndrome, all illnesses that affect the central or peripheral nervous systems.
The study was published this week under the title "Is this my finger? Proprioceptive illusions of body ownership and representation" in The Journal of Physiology.
