ABSTRACT
The Department of Defense, Department of Veterans Affairs and National Institutes of Health have invested significantly in advancing prosthetic technologies over the past 25 years, with the overall intent to improve the function, participation and quality of life of Service Members, Veterans, and all United States Citizens living with limb loss. These investments have contributed to substantial advancements in the control and sensory perception of prosthetic devices over the past decade. While control of motorized prosthetic devices through the use of electromyography has been widely available since the 1980s, this technology is not intuitive. Additionally, these systems do not provide stimulation for sensory perception. Recent research has made significant advancement not only in the intuitive use of electromyography for control but also in the ability to provide relevant meaningful perceptions through various stimulation approaches. While much of this previous work has traditionally focused on those with upper extremity amputation, new developments include advanced bidirectional neuroprostheses that are applicable to both the upper and lower limb amputation. The goal of this review is to examine the state-of-the-science in the areas of intuitive control and sensation of prosthetic devices and to discuss areas of exploration for the future. Current research and development efforts in external systems, implanted systems, surgical approaches, and regenerative approaches will be explored.
ABSTRACT
Most of the blinding retinopathies are due to progressive photoreceptor degeneration. Treatment paradigms that are currently being investigated include strategies to either halt or slow down photoreceptor cell loss, or to replace useful vision with retinal prosthesis. However, more information is required on the pathophysiological changes of the diseased retina, in particular the inner retina, that occur as a consequence of photoreceptor cell loss. Here we wished to use light damage as a stoppable insult to determine the structural and functional consequences on inner and outer retina, with the overall goal of determining whether survival of a functional inner retina is possible even if the outer retina is damaged. Mice were exposed to a 20-day light-damage period. Electroretinograms (ERG) and morphology were used to assess subsequent recovery. Outer retina was monitored analyzing a-waves, which represent photoreceptor cell responses, and histology. Integrity of the inner retina was monitored, analyzing b-waves and oscillatory potentials (OP1-OP4) and immunohistochemical markers for known proteins of the inner retina. All six ERG components were significantly suppressed with respect to amplitudes and kinetics, but stabilized in a wave-dependent manner within 40-70 days after the end of light exposure. As expected, damage of the outer retina was permanent. However, function of the inner retina was found to recover significantly. While b-wave amplitudes remained suppressed to 60% of their baseline values, OP amplitudes recovered completely, and implicit times of all components of the inner retina (b-wave and OP1-OP4) recovered to a level close to baseline values. Histological analyses confirmed the lack of permanent damage to the inner retina. In summary, these data suggests that the inner retina has the potential for significant recovery as well as plasticity if treatment is available to stop the deterioration of the outer retina.
