Article

Practicing arm and gait movements with robotic assistance after
neurologic injury can help patients improve their movement ability, but patients
sometimes reduce their effort during training in response to the assistance.
Reduced effort has been hypothesized to diminish clinical outcomes of robotic
training. To better understand patient slacking, we studied the role of visual
distraction and auditory feedback in modulating patient effort during a common
robot-assisted tracking task. METHODS: Fourteen participants with chronic left
hemiparesis from stroke, five control participants with chronic right hemiparesis
and fourteen non-impaired healthy control participants, tracked a visual target
with their arms while receiving adaptive assistance from a robotic arm
exoskeleton. We compared four practice conditions: the baseline tracking task
alone; tracking while also performing a visual distracter task; tracking with the
visual distracter and sound feedback; and tracking with sound feedback. For the
distracter task, symbols were randomly displayed in the corners of the computer
screen, and the participants were instructed to click a mouse button when a
target symbol appeared. The sound feedback consisted of a repeating beep, with
the frequency of repetition made to increase with increasing tracking error.
RESULTS: Participants with stroke halved their effort and doubled their tracking
error when performing the visual distracter task with their left hemiparetic arm.
With sound feedback, however, these participants increased their effort and
decreased their tracking error close to their baseline levels, while also
performing the distracter task successfully. These effects were significantly
smaller for the participants who used their non-paretic arm and for the
participants without stroke. CONCLUSIONS: Visual distraction decreased
participants effort during a standard robot-assisted movement training task. This
effect was greater for the hemiparetic arm, suggesting that the increased demands
associated with controlling an affected arm make the motor system more prone to
slack when distracted. Providing an alternate sensory channel for feedback, i.e.,
auditory feedback of tracking error, enabled the participants to simultaneously
perform the tracking task and distracter task effectively. Thus, incorporating
real-time auditory feedback of performance errors might improve clinical outcomes
of robotic therapy systems.

Langue : ANGLAIS