American scientists have created the neural interface which allowed the patient with spinal cord injury not only to control the movements of his paralyzed brushes, but also to feel the grip and to adjust its power. Weak residual the touch sensitivity found in the primary motor cortex and strengthened through the feedback system. Several decoders decoding the information from the same electrodes and found the motor signals or tactile sensitivity. Article published in the journal Cell.
Spinal cord injuries disrupt sensorimotor communication between the peripheral and Central divisions of the nervous system. As a result the person loses the ability to move and feel your body. However, the researchers found that half of the patients with injuries of the spinal cord some of the sensory nerve fibers persistsand the sensitivity of the skin weakly reflected in the activity of the cerebral cortex. It’s not enough that a person could consciously feel the touch, but weak excitation can be enhanced by using neurominidase.
Interfaces “brain-computer” allow you to decipher the activity of the motor cortex of the brain and to use it to control a computer cursor, a robotic limb or even paralyzed hand of the patient. If you stimulate the sensory cortex, it is possible to artificially create sensitivity, but has sensory-motor control was restored only in artificial hands.
A group of scientists from the United States under the leadership of Patrick Ganser (Patrick Ganzer) of the Memorial Institute Battele tried to restore sensorimotor control of the hand in a patient whose spinal cord was damaged at the level of the fifth cervical vertebra. People felt the shoulder, forearm and thumb, but could not control the brush.
In primary motor cortex of the patient mounted electrodes to his arm hooked up the electric stimulation. The signals of the motor cortex run the grasp reaction of the hand. However, people did not feel the result and could not say whether squeezes his hand object, if you have not seen it.
The researchers electrically irritated the skin of the patient’s arm in different places and monitored the changing activity of the primary motor cortex. The SVM algorithm trained to recognize which area hand touched based on signals from electrodes of the motor cortex. Then the biceps (the sensitive part of the patient’s arm) attached to the tuning patch. She was included when the algorithm recognizes that the activity of the motor cortex that hand tightened on the subject, and the strength of the vibration corresponds to the power of touch.
After scientists were convinced that the feedback system helps the patient to understand, if he grabbed the object, it was combined with electrical stimulation of motor fibers. Of activity of the primary motor cortex algorithms simultaneously emphasized the intention to squeeze the brush and tactile sensitivity. The first ran the contraction of muscles, and the second — vibrating the bandage on the patient’s shoulder. As a result, people could not only move paralyzed with a brush, but feel the result.