Figure 1.

Data recording and analysis procedures. (A) Spinal interneuron (IN) activity and forelimb EMG activities were recorded while monkeys performed a precision grip task. (B) The signals recorded during two successive trials are shown: grip force (top), spinal interneuron firing (middle), and 20 EMG recordings (bottom). (C) Data analysis procedures. Spike-triggered averages were compiled using a spike train and rectified EMG signals (top). Cross-correlations were calculated from the neural signal, which was transformed to an instantaneous firing rate signal, low-pass filtered, and downsampled, and EMG signals, which were low-pass filtered and downsampled (bottom).