Behavioral measurements of motor readiness in mice.

Motor planning facilitates rapid and precise execution of volitional movements. Although motor planning has been classically studied in humans and monkeys, the mouse has become an increasingly popular model system to study neural mechanisms of motor planning. It remains yet untested whether mice and primates share common behavioral features of motor planning. We combined videography and a delayed response task paradigm in an autonomous behavioral system to measure motor planning in non-body-restrained mice. Motor planning resulted in both reaction time (RT) savings and increased movement accuracy, replicating classic effects in primates. We found that motor planning was reflected in task-relevant body features. Both the specific actions prepared and the degree of motor readiness could be read out online during motor planning. The online readout further revealed behavioral evidence of simultaneous preparation for multiple actions under uncertain conditions. These results validate the mouse as a model to study motor planning, demonstrate body feature movements as a powerful real-time readout of motor readiness, and offer behavioral evidence that motor planning can be a parallel process that permits rapid selection of multiple prepared actions. • Motor planning leads to fast and precise movements in mice • Motor readiness is reflected in task-relevant body features • Both the content and degree of motor readiness are reflected in body features • Mice simultaneously plan multiple actions in uncertain situations Mangin et al. show that motor planning precedes fast and precise movements in mice. Motor planning of specific actions can be read out from body features. This online readout reveals that mice simultaneously plan multiple actions in uncertain situations. [ABSTRACT FROM AUTHOR]