Characterization and decoding of cutaneous sensory feedback from the hand

Specialized mechanoreceptive organs in the superficial skin transduce external stimuli into trains of action potentials bound for the central nervous system. Although the neural basis of cutaneous tactile sensibility has been extensively investigated for more than a century, much remains to be understood regarding the cortical representation of peripheral sensory stimuli and the neural dynamics that lead to sensory perception. This work examined sensory feedback generated by cutaneous receptors in the hand and its representation in primary somatosensory cortex (SI).;The first study characterized cutaneous sensory feedback from the hand of monkeys (Macaca mulatta) using a novel experimental approach combining a traditional Reach-to-Grasp (RTG) task, Virtual Reality Simulation (VRS) and single unit recordings in SI. The results revealed that both exteroceptive and interoceptive stimuli were encoded by a common population of receptors and that both modalities were often simultaneously encoded by a linear superposition of their firing rates. Each sensory phenomenon was encoded in a varying proportion of the overall firing rate and could be distinguished and quantified. The second study developed and evaluated a method for real-time neural decoding of exteroceptive contact stimuli in a simulation of the original RTG task. The results of this study demonstrated that small populations of cortical neurons driven by exteroceptive stimuli could collaborate to form highly accurate and robust detection units.;These results offer novel insight into the cortical neural representation of peripheral exteroceptive and interoceptive feedback and pave the way for future investigations examining their role in generating sensory perception. The ability to accurately detect and convincingly elicit specific sensory percepts is an essential capability of engineered neuroprosthetic systems for restoring impaired sensory function in humans.