The Physical Brain: New Approaches to Brain Structure, Activity, and Function

By viewing the brain as a multiscale physical system it is possible to circumvent the shortcomings of abstract signal-based and statistical approaches to analysis of brain structure, activity, and function. Eigenmode approaches enable the key elements of brain structure to be isolated systematically, along with their effects on brain activity and functional measures. Physically based neural field theory permits tractable analysis from sub-mm scales to the whole brain, demonstrating the near-critical state of normal brain operation, relationships between structure and function, nonlinear dynamics, and phase transitions. Results in normal and abnormal states include experimentally verified predictions of electrical and hemodynamic signals, and the successful inversion of functional correlation measures to infer brain structure, including connectivity that cannot be measured directly. These results illustrate the power of physically based modeling to predict, explain, and unify multiple observations across scales. Furthermore, they open up ways to extend biological physics to a host of new phenomena.