Mathematical Biology seminar Thomas Luo University of Utah "A neural marker of internal decision commitment" Tuesday, March 3 1-2pm in LCB 215 Abstract: Animals process a continuous stream of sensory information and often accumulate ambiguous evidence over time to select an action. A central step in this process, the moment when an animal internally finalizes a choice and commits to it, has been difficult to identify, because it is not directly tied to sensory inputs or overt motor outputs. As a result, this covert change in brain state has remained elusive. In this talk, I will describe a neural signal that pinpoints the exact moment an animal "makes up its mind" and commits to a choice on single trials, even before any action is taken. This signal is decoded from the simultaneous activity of many neurons recorded in the frontal cortex of rats performing a decision-making task, and we refer to it as nTc ("neurally inferred time of commitment"). Before nTc, incoming evidence influences the animal's behavior; after nTc, the influence of new evidence abruptly stops to matter. In a subsequent study, we find that nTc marks an abrupt transition not only in the behavior but also in the neural activity recorded simultaneously across tens of brain regions. nTc thus provides a neural timestamp for the moment of commitment and reveals that commitment coincides with a coordinated, brain-wide state change.