For this analysis, we only considered sGFP cells within 400 μm from the PCs, because the probability for these interneurons to be connected becomes negligible this website beyond 400 μm (Figure 4C). We defined this probability as the number of common inputs divided by the total number of stimulated interneurons

and observed that it was similar between connected (0.42 ± 0.08, n = 8) and unconnected PCs (0.35 ± 0.03, n = 33; p = 0.36, Mann-Whitney; Figure 7F). This indicates that synaptically connected PCs, which are part of the same synaptic circuits, receive as many common sGFP inputs as unconnected PCs. These results overall suggest that sGFP cells appear to connect with PCs in a similar fashion, without discriminating whether these PCs are connected or not and therefore do not form specific subnetworks. We performed our initial mapping experiments with young animals (P11–P16), relatively early in the Cell Cycle inhibitor development of these circuits. It was therefore possible that the dense and unspecific

organization of inhibitory circuit would be a transitory developmental state and that similar mapping in older animals could yield sparser, perhaps more specific, functional maps. To test this hypothesis, we performed optical mapping experiments with older animals, in a range of developmental stages from P11 to P41, which encompass the normal maturation of mouse neocortical circuits through critical periods and into adulthood (Fagiolini and Hensch, 2000). We observed that the connection probability was similar throughout the range of ages examined (p > 0.05, one-way ANOVA): P11 to P12 (0.49 ± 0.04, n = 26), P13 to P14 (0.38 ± 0.03, n = 28), P15 to P17 (0.47 ± 0.06, n = 10), P18 to P20 (0.56 ± 0.06, n = 11), P22 to P23 (0.55 ± 0.05, n = 10), P26 to P30 (0.52 ± 0.12, n = 4), P34 to P35 (0.56 ± 0.04, n = 8), and P36 to P41 (0.54 ± 0.05, n = 7) (Figure 8A). It should be noted that there was a small significant

decrease in connection probability at P13–P14 (p = 0.04, compared to P11–P12; Mann-Whitney), which could indicate a potential remodeling of the connectivity in the those cortical circuits at the opening eyes stage of the development. The proportions of connected, unconnected interneurons and false positive were not significantly different for young (P11–P16) versus mature (P20–P41). The mature mapping revealed 55.8% ± 2.4% of connected sGFP cells (versus 43.2% ± 2.5% for young, p = 0.65, t test), 39.0% ± 2.5% of unconnected sGFP cells (versus 44.3% ± 2.6% for young, p = 0.85, t test) and 5.3% ± 1.0% of false positives (versus 12.5% ± 1.6% for young animals, p = 0.67, t test).