From the results of a research program carried out by the European
Laboratory for the Neuroscience of Action (LENA), it can be assumed that it
will take longer than normal to train the future softball team of the
International Space Station, although this was not really the focus of the
study. At issue is the debate over how human brains calculate
time-to-contact (TTC), a hot topic which divides neuroscientists between, on
one hand, those who believe that the muscular tension we apply as resistance
to a falling object whose flight we are about to interrupt–a vase headed
for the floor, say–is the result of processing only visual information, and
on the other hand, those who suspect that there is something else included
in the brain’s equations. That something else could be an acquired model of
gravity built into the brain and supplying needed information on
acceleration, momentum, and other parameters needed to apply just the right
amount of muscular flex to stop the object dead in its path, as we most
often do. With notable exceptions like watching drag races, acceleration of
objects is difficult information to obtain visually, and LENA scientists
designed a series of experiments to be carried out by astronauts in
microgravity during a two-week space shuttle flight. The protocol had
astronauts catching balls that were projected from the ” ceiling ” to the ”
floor ” at three different initial velocities. Astronauts’ movements were
recorded in fine detail by a video-camera-and-computer apparatus designed by
the European Space Center (CNES) and Matras Marconi Space, which amplified
and analyzed the movements thus permitting comparison to similar gestures
made on earth. When treated mathematically the results revealed a systematic
tendency on the part of the ball catchers to take into account earth’s
gravity although there was very little of that force acting on them. This
study is the latest in a 10-year long series of investigations by the
CNRS/Collège de France Laboratory of the Physiology and Perception of Action
(LPPA – one of the partners in the more recently formed LENA) into the role
played by models of the laws of Newtonian mechanics developed by the brain.
A longer space jaunt will be needed for investigation into the process of
forming or reforming this inner model. Not to mention learning how to shag a
fly ball in microgravity. (CNRS Communiqué, June 22)