Before revision:  Then, the presentation of other signals also changes the synaptic weight (during the URLetting time). We study the number of external signals to which the network can be submitted until the initial signal is considered as URLotten. We construct an estimator of the initial signal thanks to the synaptic currents  .
After revision:  Then, the presentation of other signals (noise) may also modify the synaptic weights. We construct an estimator of the initial signal thanks to the synaptic currents .