Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation

When Nathan Copeland suffered a car accident in 2004, damage to his spinal cord at the C5/C6 level resulted in tetraplegic paralysis. This left him initially at the age of 18 years old to consider a life without the use of his arms or legs, until he got selected in 2014 for a study at the University of Pittsburgh involving the controlling of a robotic limb using nothing but one’s mind and a BCI.

While this approach, as replicated in various other studies, works well enough for simple tasks, it comes with the major caveat that while it’s possible to control this robotic limb, there is no feedback from it. Normally when we try to for example grab an object with our hand, we are aware of the motion of our arm and hand, until the moment when our fingers touch the object which we’re reaching for.

In the case of these robotic limbs, the only form of feedback was of the visual type, where the user had to look at the arm and correct its action based on the observation of its position. Obviously this is far from ideal, which is why Nathan hadn’t just been implanted with Utah arrays that read out his motor cortex, but also arrays which connected to his somatosensory cortex.

As covered in a paper by Flesher et al. in Nature, by stimulating the somatosensory cortex, Nathan has over the past few years regained a large part of the sensation in his arm and hand back, even if they’re now a robotic limb. This raises the question of how complicated this approach is, and whether we can expect it to become a common feature of prosthetic limbs before long. Continue reading “Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation”

Seeking Enlightenment: The Quest To Restore Vision In Humans

Visual impairment has been a major issue for humankind for its entire history, but has become more pressing with society’s evolution into a world which revolves around visual acuity. Whether it’s about navigating a busy city or interacting with the countless screens that fill modern life, coping with reduced or no vision is a challenge. For countless individuals, the use of braille and accessibility technology such as screen readers is essential to interact with the world around them.

For refractive visual impairment we currently have a range of solutions, from glasses and contact lenses to more permanent options like LASIK and similar which seek to fix the refractive problem by burning away part of the cornea. When the eye’s lens itself has been damaged (e.g. with cataracts), it can be replaced with an artificial lens.

But what if the retina or optic nerve has been damaged in some way? For individuals with such (nerve) damage there has for decades been the tempting and seemingly futuristic concept to restore vision, whether through biological or technological means. Quite recently, there have been a number of studies which explore both approaches, with promising results.

Continue reading “Seeking Enlightenment: The Quest To Restore Vision In Humans”