Motor Learning in a Customized Body-Machine Interface

The goal of these studies is to enable persons paralyzed by spinal cord injury (SCI) to drive
powered wheelchairs and interact with computers by acting through an interface that maximizes
the effectiveness of their residual motor function. This is called a "body-machine interface"
because it maps the motions of the upper-body (arms and shoulders) to the space of device
control signals in an optimal way. In this way, paralyzed persons that cannot operate a
joystick controller because of lack of hand mobility can effectively use their whole upper
body as virtual joystick device. An important characteristic of the proposed approach is that
it is based on the possibility to control a computer or a wheelchair by bodily movements
through an interactive learning process, in which the interface adapts itself to the
subject's mobility and the subject learns to act through the interface. This study aims at
developing and testing the customization of this interface to a group of SCI participants
with tetraplegia, resulting from high-level cervical injury. The proposed research is
organized in three specific aims:

(Aim 1) To develop new functional capabilities in persons with spinal cord injury by
customizing a body-machine interface to their individual upper body mobility. After fitting
the interface to the residual movements of each subject, participants will practice computer
games aimed at training two classes of control actions: operating a virtual joystick and
operating a virtual keyboard. This study will test the ability of the subjects to perform
skilled maneuvers with a simulated wheelchair.

(Aim 2.) To test the hypothesis that practicing the upper-body control of personalized
interfaces results in significant physical and psychological benefits after spinal-cord
injury. A study will evaluate and quantify the impact of the practicing functional upper-body
motions on the mobility of the shoulder and arms by conventional clinical methods and by
measuring the subjects' ability to generate coordinated upper body movements and to apply
isometric forces. Other studies under this aim will evaluate the effects of operating the
body-machine interface on musculoskeletal pain and on the mood and mental state of the
participants.

(Aim 3) To train spinal-cord injury survivors to skillfully operate a powered wheelchair
using their enhanced upper body motor skills and customized interface parameters. Finally,
the last study will test the hypothesis that the skills learned through practice in the
virtual environment are retained for the control of an actual powered wheelchair. After
reaching stable performance in the simulated wheelchair, subjects will practice the control
of the physical wheelchair in safe a testing environment.

(Aim 4.) To understand how extensive practice with a body machine interface affects the
cortical representation of the trained limbs. A study will evaluate and quantify the impact
of the practicing functional upper-body motions on corticospinal excitability as a correlate
to sensorimotor skill learning. Participants will meet the inclusion criteria for both the
main study and satisfy the additional optional criteria. Participant will practice upper-body
movements using the body-machine interface. The study will evaluate the evolution of
corticospinal excitability in related areas of the motor cortex during the training compared
to the baseline and after a follow-up period.

If successful, this study will lead to effective operation of a highly customized interface
that adapts to the residual motor capability of its users. Physical and psychological
benefits are expected to derive from the sustained and coordinated activity associated with
the use of this body-machine interface

Inclusion Criteria:

- Age 18-65

- Injuries at C3-C6 level, complete (ASIA A) or incomplete (ASIA B and C)

- Able to follow simple commands

- Able to speak or respond to questions

Exclusion Criteria:

- Presence of tremors, spasm and other significant involuntary movements

- Cognitive impairment

- Deficit of visuo-spatial orientation

- Concurrent pressure sores or urinary tract infection

(Optional) Additional Exclusion Criteria for evaluation of corticospinal excitability using
Transcranial Magnetic Stimulation:

- Any metal in head with the exception of dental work or any ferromagnetic metal
elsewhere in the body. This applies to all metallic hardware such as cochlear
implants, or an Internal Pulse Generator or medication pumps, implanted brain
electrodes, and peacemaker.

- Personal history of epilepsy (untreated with one or a few past episodes), or treated
patients

- Vascular, traumatic, tumoral, infectious, or metabolic lesion of the brain, even
without history of seizure, and without anticonvulsant medication

- Administration of drugs that potentially lower seizure threshold [62], without
concomitant administration of anticonvulsant drugs which potentially protect against
seizures occurrence

- Change in dosage for neuro-active medications (Baclophen, Lyrica, Celebrex, Cymbalta,
Gapapentin, Naposyn, Diclofenac, Diazapam, Tramadol, etc) within 2 weeks of any study
visit.

- Skull fractures, skull deficits or concussion within the last 6 months

- unexplained recurring headaches

- Sleep deprivation, alcoholism

- Claustrophobia precluding MRI

- Pregnancy