Sensory feedback from the limbs is crucial for control of movement, and a lack of sensory feedback can make it difficult to perform even simple activities of daily living. Injuries to peripheral nerves, such as limb amputation, often result in impaired sensory function that can make tasks such as walking difficult or dangerous. Multiple projects in our lab focus on restoration of sensory function by stimulating sensory neurons in the dorsal root ganglia (DRG). These enlargements of the dorsal spinal nerves house the cell bodies from sensory neurons that convey information about touch, limb position, temperature, and pain. At the DRG, sensory neurons are completely segregated from motor neurons, allowing for precise stimulation and recording of primary afferent neurons. Importantly, these structures often remain intact after peripheral nerve injury, such as limb amputation.
Currently, the most advanced electrode arrays that are approved by the FDA for implantation to stimulate nerves and the spinal cord have only a handful of electrodes with relatively large contacts and inter-contact spaces. These devices are designed to target large regions of the spinal cord or DRG to treat pain, but are not ideal for targeting small populations of neurons to restore sensation. Multiple projects in our lab involve preclinical testing of advanced electrode technologies, with the goal of stimulating or recording from small numbers of sensory neurons. These studies involve implantation of microelectrodes into the DRG and experiments to measure the selectivity, stability, and behavioral effects of microstimulation of these structures. Additionally, by recording through these same electrodes, we can perform neurophysiology experiments to better understand the somatosensory system and its response to various sensory inputs.