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A common belief in the brain research community is that the brainstem noradrenergic system enhances the “signal-to-noise ratio” of cortical and thalamic sensory neurons. In actuality, nearly all of the studies on this issue did not report actual signal-to-noise ratios but instead report an increase in evoked firing rate versus spontaneous discharge rate for neurons. Further, these reports used “signal-to-noise” as a compelling description of their neurophysiological data, but few reports, if any, claim this to be an engineering fact.