Cue to action processing in motor cortex populations

The primary motor cortex (MI) commands motor output after kinematics are planned from goals, thought to occur in a larger premotor network. However, there is a growing body of evidence that MI is involved in processes beyond action generation, and neuronal subpopulations may perform computations related to cue-to-action processing. From multielectrode array recordings in awake behaving Macaca mulatta monkeys, our results suggest that early MI ensemble activity during goal-directed reaches is driven by target information when cues are closely linked in time to action. Single-neuron activity spanned cue presentation to movement, with the earliest responses temporally aligned to cue and the later responses better aligned to arm movements. Population decoding revealed that MI's coding of cue direction evolved temporally, likely going from cue to action generation. We confirmed that a portion of MI activity is related to visual target processing by showing changes in MI activity related to the extinguishing of a continuously pursued visual target. These findings support a view that MI is an integral part of a cue-to-action network for immediate responses to environmental stimuli.