By: Loren Kalm for Body1New hope to find solutions for limb paralysis and other neural disruptions is emerging in the field of neuroprosthetics. Paralysis, or loss of muscle function, can result in the complete loss of sensation and mobility of a limb or a portion of the body.
Paralysis is often a result of a severed neural connection that links the motor cortex of the brain to the motor neurons that cause muscle contraction, and afflicts over a quarter million Americans with spinal injuries. In such scenarios, both the cortical and skeletal muscle neurons are functional, but cannot communicate because of a damaged connection (in the spinal cord or otherwise). Neural prosthetics hope to artificially restore communication between the brain and muscle, resulting in voluntary movement.
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Management of Paralysis Related Problems:
Consult your physician about rehabilitation to prevent tightening of joints and pulmonary problems
Maintain care of skin to prevent ulcers
Practice proper nutrition
Manage bladder problems with medication or special assistance
Notice the signs of depression and call a hotline if emotional problems arise
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Initial studies involved pieces of this puzzle. Researchers recorded the electrical activity of the brain using small microelectrode arrays in monkeys. These signals could then be converted into movements in real time using a computer interface. This initially involved translating the signals into simple motions, such as moving a cursor across a computer screen, but eventually developed into complex motor movements of robotic limbs that could be controlled entirely by thinking. Patients have experienced a restoration of basic motor abilities through integrated robotic limbs that can replace amputations as large as an arm.
The other side of this technology involves artificially stimulating muscles to generate controlled movements. This process, called functional electrical stimulation (FES), has been shown to allow patients who are paralyzed from the waist down to walk with mechanical assistance.
Recently, a study from the University of Washington has combined both of these developments in monkeys, by externally wiring the brain to transmit signals to a computer and then back to motor neurons that cause muscle contraction. In doing so, the researchers were able to restore motor function to the wrist, which had undergone a temporary chemically induced muscle paralysis.
Additionally, the accuracy and fluidity of these movements improved with practice, providing hope that neuroprosthetic muscle movements could one day become comparable to natural ones. Furthermore, researchers discovered that neurons in the brain which were not initially involved in motor function could be trained to control peripheral muscles. This is significant for neuroprosthetics which could be adapted to a variety of locations in the brain.
While neuroprosthetics in the clinical setting may be years away, the future is bright for this emerging field. One consideration is the development of an implant that could transmit the electrical activity of neurons wirelessly. Patients could thus avoid complications with the cables and reduce the invasiveness of implant procedures. Neuroprosthetics are also being examined to restore connections in the brain that have been damaged. Lesions of the hippocampus from stroke, epilepsy, and Alzheimer’s can hinder the brains ability to store new memories. Scientists are currently working to formulate an implantable circuit that mimics the activity of the hippocampus and could potentially help restore memory capabilities.
