The use of novel tools such as prostheses involves the neural processes of embodiment and ownership of the tool, allowing the brain to incorporate the device into its internal model. Currently, a gap exists in the literature that describes how these processes effect the rejection or acceptance of upper limb prostheses. Prosthetic simulators are tools used within rehabilitative settings that aid amputees with becoming more familiar with their prosthetic device with the unaffected limb or have been used to investigate learning paradigms. However, it is unknown if these simulators truly emulate the neural and muscular responses of using an actual prosthesis. Neural imaging through functional near-infrared spectroscopy (fNIRS) in parallel with muscle activity readings with the use of electromyography (EMG) from the effector muscles during the use of a prosthetic simulator in typically developing population would allow for a physiological description of novel tool use, both within the brain and end effector. This data would aid in elucidating the effects of using a novel tool on brain activation, as well as differences between simulator use and prosthesis use. The objective of the study is to determine differences in lateralization of brain function during a gross manual dexterity assessment using prosthetic simulators and 3D printed prostheses. Our hypothesis is that ipsilateral hemispheric activity and end-effector co-contraction will be significantly increased during the use of the simulator in the non-preferred hand of the typically developing participants. Secondly, that prosthesis users will show significantly more ipsilateral dominance and co- contraction compared to the simulator users and typically developing controls. Should our hypotheses prove correct, we may use the knowledge gained to better inform rehabilitative programs for children receiving prostheses and create more effective simulators. To test our hypotheses, we formulated two specific aims:
Specific Aim 1 : Determine the differences in primary motor cortex hemispheric activity during the performance of motor tasks using upper-limb prosthetic simulators in typically developing children, compared to children using upper limb prostheses. We will analyze a sub-group of 20 participants already enrolled in the parent grant (10 typically developing and 10 prosthesis users) from 7 to 12 years of age and monitor their primary motor cortex activation during a gross manual dexterity test.
Specific Aim 2 : Determine the changes in co-activation index, as measured by the co-contraction of the extensor digitorum and flexor carpi ulnaris, during a maximal voluntary isometric contraction.
The objective of the study is to determine differences in lateralization of brain function during a gross manual dexterity assessment using prosthetic simulators and 3D printed prostheses. Our hypothesis is that ipsilateral hemispheric activity and end-effector co-contraction will be significantly increased during the use of the simulator in the non-preferred hand of the typically developing participants. Secondly, that prosthesis users will show significantly more ipsilateral dominance and co-contraction compared to the simulator users and typically developing controls. Should our hypotheses prove correct, we may use the knowledge gained to better inform rehabilitative programs for children receiving prostheses and create more effective simulators.
