Sensory-motor computations in a cortico-pontine pathway

Subcortical circuits decode the output from multiple cortical areas to create commands for movement. By recording during monkeys smooth pursuit eye movements, we reveal how the dorsolateral pontine nucleus (DLPN) and nucleus reticularis tegmenti pontis (NRTP) decode cortical output. Preparatory activity is inherited from the smooth eye movement region of the frontal eye fields (FEFSEM). Consistent with its effects on eye movement responses to visual motion, preparatory activity modulates the gain of pontine responses to visual motion input from visual area MT. Furthermore, the "place" code for target speed in area MT becomes the motor commands "rate" code in the pons, through linear weighting of MTs output. The division into decoding that happens in the pons and residual computations that occur downstream reveals that the pons is neither a relay nor the source of a final motor command. It is part of a complex, distributed cortical decoder for motor control.