The prediction of quantum theory that a conscious observer is required to collapse the wave equation of a coherent system and produce a unique outcome, has led many physicists to speculate about the role of quantum phenomena in consciousness. Penrose, for example, proposed in Shadows of the Mind that microtubules were somehow capable of acting as quantum transducers that could detect quantum fields and produce consciousness and indeterminate behavior in the brain. In Information Theory and Quantum Physics , H.S. Green follows the same line of reasoning and concludes that, not microtubules, but ion channels, are the seat of consciousness.