Negative feedback stabilizes memories  Excitatory (E) neurons
hold the memory. If their activity begins to slip, fast negative
feedback (red) mediated by inhibitory (I) neurons can correct
this slip before slower positive feedback loops (blue) bring the
circuit back into balance. Credit: UC Davis graphic   The work
was published Aug. 18 in the journal Nature Neuroscience.  "The
puzzle out there is: How do retain a memory without it
slipping?" said Associate Professor Goldman. "For example, if
you store a memory of the color yellow, why doesn't it slip over
time into orange?"  Earlier models used positive feedback to
maintain memories. The idea is that, if a memory starts to fade,
the circuit gets a boost.  "The problem with positive feedback
is that, without some additional mechanism, it's brittle—the
system doesn't respond well to being perturbed," said Goldman,
who also holds joint appointments in the Department of
Neurobiology, Physiology and Behavior within the College of
Biological Sciences, and the Depa