All living organisms respond adaptively to the opportunities and constraints presented by their fluctuating physical environment. For example, (1) a bacterium that survives attack by antibiotic drugs can flourish where others fail; (2) an eye that adapts to the overall level of illumination can provide vision either by night or day, enhancing an organism's prospects for survival; (3) a decision-making system, like the brain, that integrates prior experience can make better decisions about what to do with new incoming sensory information. These three examples cover a range of levels of biological organization, and have traditionally been studied by specialists who have little contact with the other levels. However, living organisms implement adaptation, learning, and decision strategies at all levels of organization, subject to some overarching rules from probability theory. Thus the study of behavior at a single level can improve the understanding at other levels. This proposed research will analyze experiments done at all three of these levels in a common framework of information theory. New techniques will be developed to extract meaning from experimental data. These tools will be used to assess the extent to which single-cell organisms, the retina, and the brain all implement common (or related) decision strategies. These new tools will be useful to researchers in many other fields, and they will be disseminated broadly. The project includes training for several graduate, undergraduate, and postdoctoral students. The project's investigators will perform a number of outreach activities, most notably the creation of an interdisciplinary undergraduate textbook addressing the newly emerging field of systems biology for students in science/technology/engineering/and math fields.
