FIG. 8.

Comparison of firing patterns in motor cortex and dmPFC. A: eigenvectors for the first 2 PCs from motor cortex are shown as black and gray lines, respectively. In addition, the cumulative sum of PC1 is plotted as the dashed line and was highly similar to PC2, both in its time course and extent of modulation. B: eigenvectors for the first 2 PCs are shown from dmPFC. As in motor cortex, the cumulative sum of PC1 is plotted as the dashed line and was highly similar to PC2. In both areas, modulation of PC1 preceded modulation of PC2 and PC2 was subsequently “persistent.” C: a comparison of the time course of modulation in PC1 from motor cortex and dmPFC shows that both areas modulated at about the same time, just before the lever press. The modulation in motor cortex was sharper than that in dmPFC and decayed at a greater rate following the lever press. D: PC2 was similar from the 2 cortical areas, but the increase in PC2 from motor cortex preceded the increase in PC2 from dmPFC.