Following their return to Earth, astronauts experience disturbances in their
ability to walk and maintain postural stability due to neural
adaptation to the microgravity conditions of spaceflight.
These changes can pose risks to crew safety and mission objectives
if nominal or emergency vehicle egress is required immediately
following long-duration spaceflight. Current research in
the Motion Laboratory is focused on understanding how exposure
to space flight produces post flight disturbances in balance
and gait control and developing training programs that will
facilitate recovery of mobility after long-duration spaceflight.
 Image right: Fully instrumented subject walking on the treadmill during
testing
The training program currently being
developed is based on the concept of adaptive generalization.
During this type of training the subject
gains experience producing the appropriate adaptive behavior
under a variety of sensory conditions and balance challenges.
As a result of this training a subject learns to solve a
class of balance and walking problems, rather than producing
a single solution to one problem. Therefore, the subject
gains the ability to "learn to learn" under a variety of conditions that challenge the balance and walking control
systems. Through a series of flight and ground-based studies
we will develop a countermeasure built around in-flight treadmill
exercise activities. By manipulating the sensory conditions
of exercise (by varying visual flow patterns, body load and
support surface stability during walking) this training regimen
will systematically and repeatedly promote adaptive change
in walking performance improving the ability of the astronaut
to adapt to a novel gravity environment. It is anticipated
that this training regimen will facilitate neural adaptation
to unit (Earth) and partial (Mars) gravity after long-duration
spaceflight.
 Image left: Subject walking on a treadmill while watching a
moving virtual scene during a balance and gait training session
The
Neuroscience Motion Laboratory has developed an integrated
data acquisition system that
allows the investigation of the interaction and synergies
of the various sub-systems used to produce coordinated
movement strategies during locomotion. Simultaneous collection
of
the many variables necessary to perform a comprehensive
investigation of these locomotor strategies after space flight
involves
the integration of multiple data acquisition systems. We
have developed a data acquisition strategy that allows
us to obtain continuous measurements of various kinematic
and
kinetic variables during protocols involving over ground
and treadmill locomotion. During various locomotion protocols the following data can be collected: 1) three-dimensional
full-body segmental kinematics using video-based motion analysis,
2) triaxial shank and head accelerations, 3) surface electromyography
(EMG) from the neck, trunk, and lower limbs, 4) heel-strike
and toe-off events using footswitches, 5) ground-reaction
forces during locomotion, and 6) dynamic visual acuity measures
during treadmill walking. The following equipment is integrated
to form the data acquisition and testing system: 1) a six
camera, high resolution video motion system (Motion Analysis
Corp. Santa Rosa, CA), 2) triaxial accelerometers (Entran
Sensors & Electronics Fairfield, NJ), 3) a seven-channel pre-amplified surface EMG amplifier
system (Therapeutics Unlimited, Davenport, IA), 4) pressure-activated
footswitches (MotionLab Systems Inc. Baton Rouge LA), 5)
a Biomobile force plate (Kistler Instruments, Amherst, NY),
6) a motor-driven instrumented treadmill (Kistler Instrument
Corp., Amherst, NY) and 8) a treadmill safety harness system
(Safe Stress Inc.). The data are simultaneously collected
using commercially available data acquisition software and
A/D boards on three PCs. In addition, support surface variation
used for gait training can be produced by placing a treadmill
on an available electrically powered 6 degree of freedom
motion base (Moog, East Aurora, New York).
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