ABSTRACT
Targeted muscle reinnervation (TMR) was developed to provide intuitive myoelectric control sites for powered prosthesis users but additionally, and unexpectedly, resulted in the potential to provide sensory feedback. Several
CONTENTS
8.0 Introduction ................................................................................................ 121 8.1 Sensory Perception and Feedback in Prostheses .................................. 122
8.1.1 The Somatosensory System .......................................................... 122 8.1.2 Importance of Sensory Feedback for Prosthesis Control ......... 123
8.2 Transfer Sensation in Targeted Reinnervation Amputees ................... 124 8.2.1 Characterization of Transfer Sensation ...................................... 125
8.2.1.1 Percept Mapping of Transfer Sensation ....................... 125 8.2.1.2 Sensitivity of Reinnervated Skin .................................. 125 8.2.1.3 Mechanoreceptor Complement in Reinnervated
Skin .................................................................................... 127 8.2.1.4 Tactile Acuity of Reinnervated Skin ............................ 130
8.2.2 Cortical Mapping of Transfer Sensation ..................................... 132 8.2.2.1 Rat Electrophysiologic Studies ...................................... 132 8.2.2.2 Human High-Density Electroencephalography
Studies .............................................................................. 136 8.3 Application of Transfer Sensation for Sensory Feedback .................... 136
8.3.1 Current Uses: Haptic Tactors ....................................................... 136 8.3.1.1 Force and Vibratory Feedback ....................................... 138 8.3.1.2 Embodiment of the Prosthetic Limb ............................ 138
8.3.2 Potential Benefits and Future Use of Targeted Sensory Reinnervation ................................................................................. 141 8.3.2.1 Leverage of Plasticity Effects ......................................... 144 8.3.2.2 Potentiation of Motor Control ....................................... 144
References ............................................................................................................. 145
months after the first TMR surgery, the patient reported that touching the skin over the reinnervated muscles felt as if the missing hand or arm were being touched. It appeared that in addition to the reinnervation of muscles by motor fibers from the transferred mixed nerves, the overlying skin had been reinnervated by sensory fibers (Kuiken et al. 2004). We call this redirected sensation transfer sensation. Because nerve transfer can result in both motor and sensory reinnervation, we will use the term targeted reinnervation instead of TMR for the purposes of this chapter. With this exciting discovery came the potential for a new way to provide intuitive sensory feedback to prosthesis users. It also raised many questions about the qualities of transfer sensation, its capacity to provide useful feedback, and its underlying neural mechanisms. In this chapter, we review the experimental characterization of transfer sensation, the neural mechanisms involved, and potential applications of this interesting and exciting phenomenon.
