Figure 5.

Neuronal activity reflecting three categories of behavioral sequences. The rasters and histograms for each motor sequence are formatted as in Figure 3. A, Activity of the pre-SMA neuron preferentially increased when left pronation was followed by left supination, reflecting the sequence of individual movements. B, Activity of the pre-SMA neuron preferentially increased when the impending first action was supination only when the second action was also supination, indicating selectivity for the forthcoming sequence of action, regardless of arm use (action-sequence selectivity). C, Pre-SMA neuron exhibiting preferential enhanced activity when the right arm performed the first motor act followed by the left arm for the second motor act, regardless of action (arm-use sequence selectivity). D, Distribution of sequence-selective neurons in the pre-SMA and SMA, exhibiting selectivity for the sequence of arm use, action, and individual movements. LS, Left supination; RS, right supination; LP, left pronation; RP, right pronation.