When cells think

When does a cell display autonomous behavior? Physics can help answer this question quantitatively. When exposed to two competing cues, a passive sensor will follow the stronger one. In contrast, an autonomous agent may follow the weaker one if it benefits an internal imperative. Over the years, my group has derived the information contained in diverse cues using the physics of molecular diffusion, fluid flow, shot noise, and thermodynamics. Synthesizing these results allows us to predict passive decision boundaries when two cues compete. Violation of these boundaries indicates cell autonomy. We compare our predictions to three separate cell migration assays, including from collaborators, using no fit parameters. We find adherence to the boundary in some cases and strong violation in others. We discuss the results in the context of cells' internal networks and their external environments. Our work reveals when cells act as passive sensors, and when, instead, they "think."