Source: The Bayesian brain: the role of uncertainty in neural coding and computation (free access)
by David C. Knill and Alexandre Pouget in Trends in Neurosciences Vol. 27, No. 12, 2004 - All rights reserved.

To use sensory information efficiently to make judgments and guide action in the world, the brain must represent and use information about uncertainty in its computations for perception and action. Bayesian methods have proven successful in building computational theories for perception and sensorimotor control, and psychophysics is providing a growing body of evidence that human perceptual computations are ‘Bayes’ optimal’. This leads to the ‘Bayesian coding hypothesis’: that the brain represents sensory information probabilistically, in the form of probability distributions.