A significant problem with current prostheses is the challenge of controlling the device without being able to ‘feel’ it. Without somatosensory feedback, cognitively demanding visual and attentional processes must be relied upon. However, restoring somatosensory feedback offers the possibility of changing a prosthetic from an extracorporeal tool into a part of the user’s body, while enabling a far more natural control scheme. Although artificial somatosensory feedback of prostheses has been attempted since the 1960s, clinical implementations are lacking.
This thesis will focus on the use of electrical stimulation to artificially activate the nervous system to restore feedback. With recent advances in electrode design, the possibility of implanting hundreds of electrodes into the nervous system is becoming a reality. However, current stimulation protocols are oriented towards using only a few electrodes. It is likely that new stimulation paradigms will be needed in order to fully take advantage of multichannel microelectrode arrays.
This dissertation examines new methods for studying somatosensory feedback. Dorsal root ganglia microstimulation with concurrent nerve-cuff recordings is used to evaluate stimulation thresholds and the types of neurons first recruited. Computational models are developed to explore recruitment beyond threshold as well as the impact of simultaneous stimulation on changing neural recruitment. Finally, an experimental model is developed that uses the cortical response to primary afferent stimulation to assess information transfer to the brain. Together, these models offer new approaches for improving somatosensory feedback stimulation paradigms
