Data from: Sensory expectations shape neural population dynamics in motor circuits

The neural basis of movement preparation has been extensively studied
during self-initiated actions where motor cortical activity during
preparation shows a lawful relationship to the parameters of the
subsequent action. However, movements are regularly triggered or corrected
based on sensory inputs caused by disturbances to the body. Since such
disturbances are often predictable and since preparing for disturbances
would make movements better, we hypothesized that expectations about
sensory inputs also influence preparatory activity in motor circuits. Here
we show that when humans and monkeys are probabilistically cued about the
direction of future mechanical perturbations, they incorporate sensory
expectations into their movement preparation and improve their corrective
responses. Using high-density neural recordings, we establish that sensory
expectations are widespread across the brain, including the motor cortical
areas involved in preparing self-initiated actions. The geometry of these
preparatory signals in the neural population state is simple, scaling with
the probability of each perturbation direction. After perturbation onset,
a condition-independent signal shifts the neural state leading to rapid
responses that initially reflect sensory expectations. Based on neural
networks coupled to a biomechanical model of the arm, we show that this
neural geometry emerges only when sensory inputs signal that a
perturbation has occurred before resolving the direction of the
perturbation. Thus, just as preparatory activity sets the stage for
self-initiated movement, it also configures motor circuits to respond
efficiently to sensory inputs.