  Synaptic connections are known to change dynamically. High-frequency
presynaptic inputs induce decrease of synaptic weights. This process is known
as short-term synaptic depression. The synaptic depression controls a gain for
presynaptic inputs. However, it remains a controversial issue what are
functional roles of this gain control. We propose a new hypothesis that one of
the functional roles is to enlarge basins of attraction. To verify this
hypothesis, we employ a binary discrete-time associative memory model which
consists of excitatory and inhibitory neurons. It is known that the
excitatory-inhibitory balance controls an overall activity of the network. The
synaptic depression might incorporate an activity control mechanism. Using a
mean-field theory and computer simulations, we find that the basins of
attraction are enlarged whereas the storage capacity does not change.
Furthermore, the excitatory-inhibitory balance and the synaptic depression work
cooperatively. This result suggests that the synaptic depression works to
improve an error-correcting ability in cortical circuits.
