Noise can enhance signal detection: optimal noise maximizes SNR
SNR: — Firing rate: —
Stochastic resonance: a subthreshold periodic signal (amplitude A < threshold θ=1) becomes detectable when optimal noise is added. The neuron fires when the noisy input crosses threshold. Too little noise: no crossings; too much noise: random firing. At optimal σ, signal-to-noise ratio (SNR) is maximized — noise is beneficial, not just harmful.