Noah
Cowan
Department
of
Mechanical
Engineering
Johns
Hopkins
University
Stabilizing the Unstable Brain
The
nervous
system
may
be
the
most
sophisticated
control
system
in
the
known
universe,
riding
at
the
helm
of
an
equally
sophisticated
plant.
Understanding
how
the
nervous
system
encodes
and
processes
sensory
information,
and
then
computes
motor
action,
therefore,
involves
understanding
a
closed
loop.
However
it
is
often
necessary
to
"isolate"
all
or
part
of
the
nervous
system
to
study
it.
But
there
is
no
guarantee
that
the
brain
is
"open-‐loop
stable"
and
in
fact
there
is
good
reason
to
believe
that
it
is
not.
Here
we
discuss
two
problems
in
which
we
first
close
a
feedback
loop
around
the
brain,
and
then
take
steps
to
perform
system
identification
of
the
stabilized
brain
in
order
to
understand
its
computations.