Before revision:  We show that, if the logarithm of this likelihood ratio is positive (i.e. when the signal is likely to be sustained), then this log-likelihood ratio can be approximately computed by a coherent feedforward loop .
After revision:  We show that, if the logarithm of this likelihood ratio is positive (i.e. when the signal is likely to be persistent, then it can be approximately computed by a coherent feedforward loop .