Figure 3.

Neural coding of grasping actions. a, d, g, Firing rate histograms are shown for three simultaneously recorded example neurons from areas AIP, F5, and M1, respectively. Each line represents the average firing rate for a specific grasping condition (i.e., 50 objects) versus time. The color code matches the object shape as in Figure 1b. b, e, h, Cross-modulation depth plots reflect the relative difference in firing rate between all pairs of grasping conditions (50 × 50 pairs) for all five epochs. Firing rates were normalized relative to the maximum MD found across all epochs. Pixels toward red represent pairs with maximum MD, whereas pixels toward blue represent pairs without difference in firing rate. c, f, i, Furthermore, a multicomparison analysis revealed significant differences (in red) between condition pairs. The order of columns/rows for cross-modulation depth- and multicomparison plots is the same as in Figure 5a. a–c, The AIP neuron showed the highest MD during the cue epoch and an additional bump during the hold epoch. d–f, The example F5 neuron demonstrated a high MD in the planning epoch and an additional increase during motor execution. g–i, The M1 motor neuron showed no significant coding during motor preparation (i.e., cue and planning) but became highly active during motor execution (i.e., movement and hold). Horizontal brackets indicate significant correlation coefficient c of MD maps between epochs.