Chicago researchers seek to produce an advanced prosthetic limb that will not only provide robust movement, but also authentic sensations. Trailblazers in brain stimulation, Bensmaia’s team works with rhesus macaque monkeys whose sense of touch is nearly identical to that of humans. “They use their hands to manipulate objects and to explore their environment the same way we do,” he says.
In his lab, Bensmaia has taught these primates to differentiate the location and force of touches applied to their skin. As the animals perform these tasks, electrodes implanted in the touch area of their brains record the neural activity evoked by each different sensation. The goal is ultimately to reproduce that activity through electrical stimulation delivered through these same electrodes.
The first human trials are set to begin soon. “If the human trials are successful, we may see people with terminator-like robotic arms walking around or sitting next to us on the bus,” he says. “This is a radical step toward the future where these machines will actually become extensions of our brains. We’re at the beginning stage, but the possibilities are staggering.”
Our ability to manipulate objects relies fundamentally on sensory signals originating from the hand. To restore motor function with upper-limb neuroprostheses requires that somatosensory feedback be provided to the tetraplegic patient or amputee. Accordingly, we have developed approaches to convey sensory information critical for object manipulation—information about contact location, pressure, and timing—through intracortical microstimulation of somatosensory cortex. In experiments with nonhuman primates, we show that we can elicit percepts that are projected to a localized patch of skin, that track the pressure exerted on the skin, and that signal the timing of contact events. We anticipate that the proposed biomimetic feedback will constitute an important step in restoring touch to individuals who have lost it.
Our ability to manipulate objects dexterously relies fundamentally on sensory signals originating from the hand. To restore motor function with upper-limb neuroprostheses requires that somatosensory feedback be provided to the tetraplegic patient or amputee. Given the complexity of state-of-the-art prosthetic limbs and, thus, the huge state space they can traverse, it is desirable to minimize the need for the patient to learn associations between events impinging on the limb and arbitrary sensations. Accordingly, we have developed approaches to intuitively convey sensory information that is critical for object manipulation—information about contact location, pressure, and timing—through intracortical microstimulation of primary somatosensory cortex. In experiments with nonhuman primates, we show that we can elicit percepts 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 phasic intracortical microstimulation at the onset and offset of object contact that mimics the ubiquitous on and off responses observed in primary somatosensory cortex to complement slowly varying pressure-related feedback. 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.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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