The term action of consciousness is used to refer to an influence, such as psychokinesis or free will, that produces an effect on matter that is correlated to mental intention, but not completely determined by physical conditions. Such an action could not conserve energy. But in that case, one wonders why, when highly accurate measurements are done, occasions of non-conserved energy (generated perhaps by unconscious PK) are not detected. A possible explanation is that actions of consciousness take place within the (...) limits of the uncertainty principle. Two models are reviewed that, using the latter assumption, propose that consciousness can originate an action potential in the brain. One (that of Eccles) uses the latter assumption only, and the other (that of Burns) additionally assumes that consciousness acts, within those limits, by ordering quantum fluctuations. (shrink)