Supplementary Figure 12: The proportions of Sox6+, COUP-TFII+ and Sp8+ interneurons in the monkey frontal, temporal and occipital lobe are different.

(a) In 6-month-old and 17-month-old monkey brains, a higher proportion of COUP-TFII+ and/or Sp8+ interneurons was found in the frontal lobe neocortex (prefrontal cortex), while a higher proportion of Sox6+ interneurons was found in the neocortex of the temporal (lateral temporal cortex) and occipital lobe (primary visual cortex). (b–d) The percentage of different subtypes of interneurons that expressed transcription factors in the 6-month-old monkey prefrontal cortex. (e–g) The percentage of different transcription factors that expressed interneuron markers in the 6-month-old monkey prefrontal cortex. (h–j) The percentage of different transcription factors that expressed interneuron markers in the 17-month-old monkey prefrontal cortex. (k) Schematic diagram showing the origin and classification of monkey and human neocortical interneurons. We propose that the majority of neocortical interneurons in the monkey and human brain originate from the MGE, dLGE and CGE of the ventral telencephalon (see quantitative data in Fig. 5 and Fig. 6). MGE-derived neocortical interneurons (Sox6+) mainly includes PV+, SOM+, nNOS+, CB+ and NPY+ interneurons. PV+ interneurons represent a distinct subpopulation of MGE-derived neocortical interneurons, whereas SOM+, nNOS+ and CB+ interneurons largely overlap. The vast majority of NPY+ interneurons express SOM and nNOS but not CB. NPY+ interneurons strongly express SOM and nNOS, representing type I nNOS+ interneurons that have large somata. Weakly Reelin (W-Reelin)+ interneurons are derived from the MGE, which we only analyzed in the monkey neocortex. W-Reelin+ interneurons express SOM, nNOS and CB, but not NPY. A small subset of COUP-TFII+ interneurons is derived from the dorsal/caudal MGE (Sox6+). These interneurons express SOM and nNOS, but not CB or NPY. A small fraction of MGE-derived CR+/Sox6+ interneurons are present in the monkey but not human neocortex. These interneurons express SOM and nNOS, but not CB, NPY or COUP-TFII. Dorsal LGE and CGE (dLGE/CGE)-derived neocortical interneurons (COUP-TFII+ and/or Sp8+) mainly includes CR+, VIP+ and strongly Reelin (S-Reelin)+ interneurons. The vast majority of CR+ interneurons expresses COUP-TFII and/or Sp8, contributing to the largest population of dLGE/CGE-derived interneurons. Nearly all VIP+ and S-Reelin+ interneurons that express COUP-TFII and/or Sp8 but not Sox6 are derived from the dLGE/CGE. A subpopulation of S-Reelin+ interneurons and the majority of VIP+ interneurons also express CR.