Oculomotor correlates of perceptual decision making during learning

Associating a perceptual decision with an action can lead to a representation of the process of forming the decision in circuits that prepare the action. We explored how this close relationship between decision and motor circuits was shaped by experience. We trained naïve monkeys to decide the direction of a weak motion stimulus. Discrimination threshold, a measure of the monkeys\u27 sensitivity to weak motion signals, improved steadily over nearly two years of training. Throughout training, we assessed developing oculomotor commands using saccades evoked with microstimulation of the frontal eye field while the monkey was viewing the motion stimulus and forming the direction decision. In monkeys already trained extensively on this task, these developing commands can reflect both the impending saccadic response and the accumulation of motion evidence used to select that response. We found that from the earliest stages of training, even as the monkeys were learning the visuomotor association, these developing commands reflected the impending saccadic response. As training progressed, these commands, like behavioral performance, became increasingly sensitive to weak motion signals. Thus, an oculomotor representation of the perceptual decision process was evident throughout training, evolving steadily to match concomitant gains in perceptual sensitivity. The results suggest that the brain can learn to treat some perceptual decisions as problems of motor selection and then over time shape how this process interprets incoming sensory information to select the appropriate motor response