Ivan R. Slootweg, Radboud UniversityMarch 29, 2024I. ABSTRACTProprioception is crucial in intuitive control of prosthetic limbs and therefore contributes to intuitive prosthetic use. The agonist-antagonist myoneural interface (AMI) is an prosthetic innovation with enhanced control, reduced pain, and heightened proprioceptive sensation in clinical experiments. Furthermore, studies have addressed surgical techniques to make this myoelectric interface available to a larger group of patients. A narrative review on AMI’s developmental process, surgical implementations, and validation has been conducted for clinical and pre-clinical experimental research, embedded in a theoretical background on feedback control and proprioception. The closing chapter on magnetomicrometery serves to illustrate how motor control reading, as an example component, can benefit from technical innovations to enhance the Intuitive prosthetic control with AMI.Keywords: agonist-antagonist; myoneural; prosthetic; motor control; proprioception; magnetomicrometery;
Furthermore, the study conrmed the basic working principle of AMI that was evaluated in the earlier fundamental studies on a cognitive level, as the proprioceptive activity in the brain demonstrated strong correlation with muscle activation. Other connectivity analyses in resting state indicated a contrast in information reliance for prosthesis proprioception among the study groups. Whereas TA subjects had the highest coupling of the sensorimotor system by visual areas, users of AMI had lower coupling of these systems an experienced higher phantom sensation. These are considered as indications for preservation of proprioceptive neurophysiology of the lower limb by an AMI. A similar study with fMRI was performed in resting state on the same population . This study had a stronger focus on prosthesis embodiment and limb sensation, which are important factors that can
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Lower coupling of salience networks and motor execution networks was observed in AMI subjects compared to TA subjects, indicating a weaker connection between areas responsible for motor control and dictating focus on salient stimuli. This could be related to less reliance of motor control on visual information in AMI users, which was found in . In support of this, a weaker connection of the visual cortex and salience networks was observed in AMI subjects. Other support for restored proprioception in AMI users is derived from indications for less information consolidation during movements. More interestingly, other connectivity analyses even indicate signicant decrease of neuropathological signatures that are present in TA subjects. These ndings of neural plasticity and less reliance on visual input are potential indicators of less
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Furthermore, sensorimotor connectivity is argued as an indicator of embodiment as it has been associated with phantom sensation which is related to embodiment . In support of such ndings, Chicos, Rangaprakash, Barry, et al. provide multiple neurophysiological indicators of neuroplasticity in amputees and exploitation of this in AMI subjects, indicated by network reorganisation. V. READING MOTOR CONTROL SIGNALS WITH MAGNETOMICROMETRY
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A. Afferent control signals The developmental history of AMI has used sonomicrometry and EMG for muscle activity measurements. Such muscle measurements inform the commands for prosthesis control and fast, accurate and high-resolution control is paramount for prosthesis embodiment and reliable proprioception , . For this reason, the development of signal transduction techniques to meet such requirement is of high value for leveraging the proprioceptive information 6 AMI can deliver to prosthesis users and in turn for intuitive prosthetic control. For AMI, such techniques should facilitate observations of efferent nerve intentions in the agonist stream. Whereas wireless surface nerve recordings are not suitable due to the high noise ratio and location deep in the residuum, implantable nerve sensors have biocompatibility problems and bring problems of recording selectivity and noise due to their small size. Therefore,
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