Friday, August 28, 2015

John Choi: September 3rd

Note that this seminar will be at 10:30am on Thursday, not the usual lab Wednesday lab meeting time.

 Title: Optimal Control for Developing Somatosensory Neural Prosthetics

Abstract: Lost sensations, such as touch, could one day be restored by electrical or optogenetic stimulation along the sensory neural pathways. Used in conjunction with next-generation prosthetic limbs, this stimulation could artificially provide cutaneous and proprioceptive feedback to the user. Microstimulation of somatosensory brain regions has been shown to produce modality and place-specific percepts, and while psychophysical experiments in rats and primates have elucidated the range of perceptual sensitivities to certain stimulus parameters, not much work has been done for developing encoding models for translating mechanical sensor readings to microstimulation. Particularly, generating spatiotemporal patterns for explicitly evoking naturalistic neural activation has not yet been explored. We therefore approach the problem of building a sensory neural prosthesis by first modeling the dynamical input-output relationship between multichannel microstimulation and subsequent field potentials, and then optimizing the input pattern for evoking naturally occurring touch responses as closely as possible, while constraining inputs within safety bounds and the operating regime of our model. In my work, I focused on the hand regions of VPL thalamus and S1 cortex of anesthetized rats and showed that such optimization produces responses that are highly similar to their natural counterparts. The evoked responses also preserved most of the information of physical touch parameters such as amplitude and stimulus location. This suggests that such stimulus optimization approaches could be sufficient for restoring naturalistic levels of information transfer for an afferent neuroprosthetic.

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