A study explores the neuropsychological basis for body representation in monkeys. A sense of ownership of one's own body is a central element of self-consciousness. The psychological and neurological mechanisms underlying this sense can be investigated through illusions, such as the rubber hand illusion, in which a person perceives an artificial object as part of themselves. Liping Wang and colleagues developed an experimental paradigm combining a rubber hand illusion with a behavioral task, which enabled the illusion to be observed and quantified in monkeys as well as in humans. In experiments involving 25 human participants, ages 18-28 years, and 4 adult male rhesus macaques, the authors measured the difference between a participant's perceived and actual arm position--termed proprioceptive drift--as a function of the disparity between the "real" and "illusory" arm positions. In both humans and monkeys, proprioceptive drift increased with disparity for small disparities, but plateaued or decreased at large disparities, suggesting that the strength of the illusion decreased with increasing disparity. The activity of neurons in the premotor cortex of monkeys' brains, recorded during the experimental task, correlated with the measured proprioceptive drift, and a Bayesian Causal Inference model of sensory integration reproduced the observed drift-disparity relationship. The results suggest how the brain establishes a sense of body ownership, according to the authors.
Article #19-02334: "Statistical inference of body representation in the macaque brain," by Wen Fang et al.
MEDIA CONTACT: Liping Wang, Chinese Academy of Sciences, Shanghai, CHINA; tel: +86-21-54921691, +86-1522-1077-693; e-mail: lipingwng@gmail.com
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Journal
Proceedings of the National Academy of Sciences