Patterns of excitatory and inhibitory motor activity were related during aimed scratches. Cross-correlations were computed for all combinations of motor activity (see Materials and Methods), and the resulting curves for each of the animals were overlaid (gray curves in A–F, N = 6 animals). For each combination, a mean curve was also computed (black curves in A–F). A, CI₁ versus SETi. B, CI₁ versus FETi. C, CI₁ versus flexor motor neurons. D, SETi versus FETi. E, SETi versus flexor motor neurons. F, FETi versus flexor motor neurons. To emphasize the temporal relationships between activity of CI₁ and each of the other motor neuron recordings, the individual cross-correlation plots were also normalized to a peak-to-peak amplitude of 1 and centered before being averaged across animals (inset).