Measuring entropy in functional neuroscience: Pathophysiological and clinical applications

A biological system obtains information, reacts to stimuli, and modifies its behavior to adapt to the environment via complex control systems. A healthy system is expected to adequately adapt to a variety of changes. Physiological signals obtained from a healthy individual should contain rich information and complex behaviors. Entropy-derived measures have been used to access the complexity of the physiological signals. Aging or diseased status usually shows reduced entropy values and loss of complexity within the dynamics of physiological output. In this article, we aim to review the available evidence related to the pathophysiological nature of complexity and the clinical applications of entropy-derived measures in varied neurological disorders.