Since the first of June is also the first Saturday, this month's Meetup is all sneaky and early. Get ready for some awesome: a long description, but so worth it. FOR SCIENCE!
Our ability to manipulate objects relies fundamentally on sensory signals from the hand. To restore motor function with upper-limb neuroprostheses requires that tactile feedback be provided to the tetraplegic patient or amputee. With this in mind, we have developed approaches to intuitively convey three critical types of tactile information for object manipulation by electrically stimulating a region of the brain that is known to receive tactile information from the hand, namely the primary somatosensory cortex (S1).
Specifically, we wish to signal
-Contact location [which parts of the prosthetic hand are in contact with the object?]
-Contact pressure [how much pressure does it exert on the object?], and
-Contact timing [when is contact with the object initiated and terminated?].
In experiments with non-human primates, we show that we can elicit tactile sensations that are projected to a localized patch of skin and that track the pressure exerted on the skin. In a real-time application, we demonstrate that animals can perform a tactile discrimination task equally well whether mechanical stimuli are delivered to their native fingers or to a prosthetic one.
Finally, we propose that the timing of contact events can be signaled through brief bursts of electrical stimulation at the onset and offset of object contact that replace the on and off responses observed in S1.
We anticipate that the proposed biomimetic feedback will considerably increase the dexterity and embodiment of upper-limb neuroprostheses and will constitute an important step in restoring touch to individuals who have lost it.
ABOUT THE SPEAKER:
Sliman J. Bensmaia received a B.S. in cognitive science from the University of Virginia, Charlottesville, in 1995, and a Ph.D. in cognitive psychology at the University of North Carolina at Chapel Hill, in 2003, under the tutelage of Dr. Mark Hollins. He was then a Postdoctoral Fellow with Kenneth O. Johnson at the Krieger Mind/Brain Institute of The Johns Hopkins University, Baltimore, MD. Currently, Bensmaia is an Assistant Professor in the Department of Organismal Biology and Anatomy at the University of Chicago, Chicago, IL, where he studies neural coding and the neural basis of perception in the somatosensory system. He combines neurophysiology, psychophysics, and computational modeling to investigate the tactile processing of form, motion, texture, and vibration. The general approach consists in measuring an aspect of perception on human subjects and recording the responses evoked in peripheral afferents and in cortical neurons in macaque monkeys. Then, using a variety of mathematical methods, he tries to discover what aspect of the neuronal responses accounts for perception. Bensmaia also invokes basic scientific findings from his lab to develop approaches to convey somatosensory feedback in upper-limb neuroprostheses.