22Two distinct processes contribute to changes in motor commands during reach adaptation: 23 reward based learning and sensory error based learning. In sensory error based learning, the 24 mapping between sensory targets and motor commands is recalibrated according to error 25 feedback. In reward based learning, motor commands are associated with subjective value, 26 such that successful actions are reinforced. We recorded EEG from humans of either sex to 27 identify and dissociate the neural correlates of reward prediction error (RPE) and sensory 28 prediction error (SPE) during learning tasks designed to isolate each response. We designed a 29 visuomotor rotation task to isolate sensory error based learning in response to SPE, which was 30 induced by altered visuospatial feedback of hand position. In a reward learning task, we 31 isolated learning in response to RPE, which was induced by binary reward feedback. We found 32 that a fronto-central event related potential called the feedback related negativity occurred 33 specifically in response to RPE during reward based learning, while a more posterior component 34 called the P300 was associated with SPE during a visuomotor rotation task. These findings 35 reveal a dissociation between well characterized EEG signatures of error processing in two 36 distinct motor learning processes.
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Significance Statement 44Adaptation of motor output to changing task demands and dynamic environments is thought to 45 occur on the basis of distinct forms of prediction error. Reward prediction error occurs when 46 the subjective value of an outcome is different than the expected value, while sensory 47 prediction error occurs when the low-level sensory consequences of motor commands are 48 different than predicted. It remains unclear how EEG activity patterns associated with error 49 processing apply to these distinct forms of motor adaptation. We found that an event related 50 potential component called the feedback related negativity responded only to reward 51 prediction error, while the P300 component is modulated by sensory prediction error and 52 correlated to sensory error based learning.