Cutaneous Hypersensitivity and Balance Control in Humans (Hypersole)
Research Area: Nervous and Vestibular Systems
Expedition(s): 23- 28
Principal Investigator(s): ● Leah Bent PhD, University of Guelph, Guelph, Ontario, Canada
RESEARCH OBJECTIVES
Cutaneous Hypersensitivity and Balance Control in Humans (Hypersole) will use a vibration
device and monofilaments (similar to fishing line) to record the sensitivity of these receptors in
9 astronauts. Researchers are documenting, for the first time, any changes in the skin sensitivity
of each astronaut’s foot sole in order to identify which receptors may be influenced by a period
of weightlessness. Coupled with tests that assess changes in astronauts’ abilities to maintain
their balance, these measures will help establish how increased skin sensitivity contributes to
balance control.
EARTH BENEFITS
Project results are expected to add significantly
to existing studies of the aging process, which
includes reductions in information relayed by
skin sensors that lead to a loss of balance
control and, among the elderly especially, a
greater incidence of falls.SPACE BENEFITS
Anecdotal evidence from astronauts suggests
that the tingling sensation some feel in their
feet while in space and for short periods back
on Earth may be the response of different
sensory receptors in the skin that naturally
compensate for the re-weighting of sensory
information due to the decreased input from
the vestibular, or inner ear, system in an
environment of microgravity. The research has
the potential to impact future applications to
further understand skin contributions to
balance control in an altered gravity-inertial
environment for space exploration.RESULTS
Vibration frequencies were chosen to target the 4 classes of mechanoreceptors: 3 and 25Hz for
slowly-adapting receptors; 60 and 250Hz for fast-adapting receptors. Functional balance test
scores (computerized dynamic posturography [CDP]) were compared to skin sensitivity
changes. It was hypothesized that skin sensitivity would increase following spaceflight and
Image shows the set up for the vibrotactile
sensitivity threshold test performed during the
experiment. Changes in sensitivity were assesses
on 3 locations on the plantar surface of the foot
using a mini shaker applying vibration through a
probe with a contact surface area of 2 mm in
diameter. Foam templates were developed for each
crew member using orthopedic foam. Holes were
made to allow room for the insertion of the vibration
probe for each of the three testing locations on the
plantar surface of the foot. Image courtesy of Leah
Bent, University of Guelph.