Body-Machine Interfaces after Spinal Cord Injury: Rehabilitation and Brain Plasticity

Abstract

The purpose of this study was to identify rehabilitative effects and changes in white matter microstructure in people with high-level spinal cord injury following bilateral upper-extremity motor skill training. Five subjects with high-level (C5–C6) spinal cord injury (SCI) performed five visuo-spatial motor training tasks over 12 sessions (2–3 sessions per week). Subjects controlled a two-dimensional cursor with bilateral simultaneous movements of the shoulders using a non-invasive inertial measurement unit-based body-machine interface. Subjects’ upper-body ability was evaluated before the start, in the middle and a day after the completion of training. MR imaging data were acquired before the start and within two days of the completion of training. Subjects learned to use upper-body movements that survived the injury to control the body-machine interface and improved their performance with practice. Motor training increased Manual Muscle Test scores and the isometric force of subjects’ shoulders and upper arms. Moreover, motor training increased fractional anisotropy (FA) values in the cingulum of the left hemisphere by 6.02% on average, indicating localized white matter microstructure changes induced by activity-dependent modulation of axon diameter, myelin thickness or axon number. This body-machine interface may serve as a platform to develop a new generation of assistive-rehabilitative devices that promote the use of, and that re-strengthen, the motor and sensory functions that survived the injury.

Cerebellar contribution to sensorimotor adaptation deficits in humans with spinal cord injury

“…Since sensory input is often altered after SCI 7 , an advantage of making sensory predictions is that the brain does not have to wait for sensory input to act. For example, studies using body-machine interfaces found that humans with SCI improve their limb function by learning a predictive map between their residual motion and a low dimensional control space 68 , 69 . If cerebellar atrophy limits the ability to adapt movements to new demands, some strategies might be helpful to consider.…”

Guiding functional reorganization of motor redundancy using a body-machine interface

“…Previous studies reported that training upper body movements with a BoMI increased muscle strength and range of motion in individuals with complete injuries [9], improved symmetry and altered the pattern of muscle activity [11]. In addition, some preliminary studies suggested that the interface can be reprogrammed to progressively encourage participation in skilled activities of more distal parts of the body [10,52].…”

“…Recently, BoMI's have been proposed as instruments for functional retraining [10][11][12]. In the rehabilitative context, the BoMI can be configured to represent specific patterns of coordination that would be desirable for the user to practice/learn, that take the form of a forward map from body motion to effector positions.…”

Autonomy in Rehabilitation Robotics: An Intersection

“…Instead, the operation of an assistive machine that replaces lost function also might be used to regain lost function. We are starting to see this explored with novel interfaces that provide rehabilitation benefits through their operation (149), and are used to control computers and wheelchairs. A therapy paradigm might adapt how much and what sort of autonomy assistance is provided by the robot, in order to encourage the recovery of motor function-as we have seen in machines whose purpose it is to rehabilitate the body (145,146).…”