Creating a multisensory body representation for movement prediction of artificial limbs.

• Applicant: Dr. Celia Foster
• Subject Area: Biological Psychology and Cognitive Neuroscience ; Human Cognitive and Systems Neuroscience
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 545902796

Having an extra hand could be incredibly useful in our daily lives, especially when we need to perform a complex task or lose the use of one hand due to an injury. But can our brain incorporate a new body part into our body representation, allowing us to use it just like any other body part? Our brain receives information about our body shape and posture from a wide variety of multisensory inputs, including touch location on the skin and proprioceptive inputs from the muscles that signal our current limb posture. This multisensory information is then integrated into a body representation that allows us to move precisely and predict the sensory outcomes of our movements. In this project, we will test whether the brain can develop a new body part representation for an additional robotic thumb, the Third Thumb. Participants will learn to use the toe-controlled Third Thumb over a validated 4-day training period. We will compare behaviour and brain responses pre- and post-training to determine how sensorimotor coding develops through experience. First, we will use a touch localisation paradigm to test whether participants can learn to accurately locate touch on the Third Thumb in external space. This ability requires participants to combine information about touch location on the Third Thumb with the current Thumb posture. Second, we will record participants’ brain activity using fMRI as they perform this task. This will allow us to identify which brain regions encode touch location on the Thumb, Thumb posture, and the integration of this information to generate an external-spatial touch location. We predict that touch localisation will depend on volitional motor control of the Thumb’s movements that is learned through training, and that this ability will be enabled by the posterior parietal cortex integrating touch and posture information. We will also compare how the brain encodes touch and posture for the Third Thumb to how it encodes this information for our own body and a handheld tool, allowing us to determine whether similar or different neural processes are used to encode additional robotic body parts, our own body, and/or handheld tools. Lastly, we will examine participants’ behavioural performance using the Third Thumb when alterations are made to a variety of specific sensory and motor Thumb properties. The degree of performance impairment and time course of adaptation to each alteration will indicate how essential each property is for the newly developed body part representation. Thus, this will indicate which sensorimotor cues are most vital to allow us to effectively use an additional robotic body part. Together, this project will identify the neural mechanisms that allow us to incorporate a new body part into our body representation. Harnessing this knowledge will guide engineers and designers to develop artificial body parts that can best replace lost function and/or enhance existing movement abilities.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professorin Dr. Tamar Makin