Ranking brain regions according to the mean inverse of the cost of controlling the network.

<p><b>a</b>) Order corresponding to the linear case. Given is the mean ± SEM of N = 41 subjects. Inputs entering regions in the leftmost part of the order control Alzheimer’s activity at a lowest cost. <b>b</b>) Graphical representation with the approximated location of the brain regions. The size of the spheres is directly proportional to the mean values in panel (<b>a</b>). Panels (<b>c</b>,<b>d</b>) are analogous to (<b>a</b>,<b>b</b>) except that the strength of the nonlinearity has been set to <i>γ</i> = 200 <i>s</i>⁻²<i>mV</i>⁻² and a new ranking is obtained. The red sphere represents the right postcentral gyrus, which yielded uncontrollable nonlinear systems for all the subjects in the sample.