Fig 3. Stochastic resonance occurs when noise is limited to the depolarising phase of the stimulus.

(A) Superimposed responses to blocks of 5 stimuli consisting of only step, yielding no action potential, or steps + noise, yielding 5 spikes. (B) Typical example of normalized power norm C₁ showing a clear maximum at intermediate noise variance. Squares represent C₁ values of individual blocks; black dots indicate average values. This curve was obtained from one of the few experiments performed using I-clamp FAST setting. (C) Responses to two sets of random numbers in different neurons, indicating that the effect of noise is not a mere summation onto the step, but rather a real resonance.