The Development of Neural Inhibition across Species: Insights from the Hurst Exponent.

The maturation of inhibitory neurons is crucial for regulating plasticity in developing brains. Previous work has suggested that the Hurst exponent, the measure of autocorrelation in time series, reflects inhibition, but empirical data supporting this link are sparse. Here, we demonstrate significant spatial correlations between the Hurst exponent and ex vivo parvalbumin (PV) inhibitory mRNA expression in human children and adults, as well as between the Hurst exponent and PV-positive cell counts in mice, across both sexes. We further identified developmental plateaus in inhibition, as indicated by both PV inhibitory mRNA expression and the Hurst exponent, occurring prior to adolescence in humans and rats. In sum, this work suggests that the Hurst exponent can be used to study the development of inhibition in vivo and to understand inhibitory development across species.