Decay of connectivity density over distance.

<p>A: Connectivity density as a function of distance. The distance was binned in 50 µm bins, and the connectivity density was evaluated at each distance. Error bars are SEM of all the cultures. Different colors represented different frequency ranges. Solid lines are exponential function fits to the data (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105324#s2" target="_blank">Materials and Methods</a>). In the legend, the decay lengths of the function fits are displayed. Inset is the same figure plotted in semi-log space. Exponential functions fit the data nicely, and give us the decay length λ. Consistent with other network properties, we observed differences in different frequency ranges in cortex, but not in hippocampus. B: Results of significance tests for the decay length λ. The tests were done among different scales in the same structure, and different structures at the same scales (black lines). The significance was evaluated from the standard deviations of λ, assuming a normal distribution. One star signifies p<0.05 significance; two stars are p<0.01 significance. While we saw no significant differences in hippocampus, the high frequency range in cortex was significantly different from the other two frequencies.