Adaptive biasing of action-selective cortical build-up activity by choice history

Decisions under uncertainty are often biased by the history of preceding sensory input, behavioral choices, or received outcomes. Behavioral studies of perceptual decisions suggest that such history-dependent biases affect the accumulation of evidence within trials and can be adapted to the correlation structure of the sensory environment. Here, we systematically varied this correlation structure while human participants performed a canonical perceptual choice task. We tracked the trial-by-trial variations of history biases via behavioral modeling and of neural signatures of evidence accumulation via magnetoencephalography (MEG). The history bias was flexibly adapted to the environment, and it exerted a selective effect on the build-up of action-selective motor cortical activity during decision formation, over and above the impact of the current stimulus. We conclude that the build-up of action plans in human motor cortical circuits is shaped by dynamic prior expectations that result from an adaptive interaction with the environment.