Paper/Tononi1994complexity

author: - Giulio Tononi - Olaf Sporns - Gerald Edelman url: “https://www.pnas.org/content/91/11/5033.short”

A measure for brain complexity: relating functional segregation and integration in the nervous system

This controversy mirrors two contrasting properties that coexist in the brains of higher vertebrates: the functional segregation of different brain regions and their integration in perception and behavior.

A balance can “arise naturally through constructive and correlative properties of reentry” see Reentry

• Tononi1992reentry
• Sporns1991modeling

Different neuronal groups are functionally segregated if their activities tend to be statistically independent when these groups are considered a few at a time. Conversely, groups are functionally integrated if they show a high degree of statistical dependence when considered many at a time.

$I(X)$ is defined as the difference between the sum of the entropies of all individual components … considered independently and the entropy of $X$ considered as a whole:

$$I(X) = \sum_{i=1}^{n} H(x_i) - H(X).$$