Regimes and mechanisms of transient amplification in abstract and biological neural networks
Fig 9
The relationship between E-to-I and E-to-E connectivity strengths alters the imaginary distribution of eigenspectra of Dalean networks.
A, Schematics of the mean-field analysis of a network with a group of excitatory (E) and a group of inhibitory (I) neurons. The mean weight from E-to-E, E-to-I, I-to-E, and I-to-I are represented by WEE, WIE, WEI, and WII, respectively. B, Weight matrix of a simplified network from panel A [10]. Inhibitory connections are optimised by the SOC algorithm [8]. C, Imaginary diameter of a network with 100 excitatory and 100 inhibitory neurons as a function of the ratio E-to-I to E-to-E weights. D, Feedforward (orange) and spectrum (red) norm as a function of the ratio E-to-I to E-to-E weights for the same networks from panel C. E, Maximum norm per initial condition for different ratios E-to-I to E-to-E weights. Grey dotted line indicates response norm that is 50% larger than the norm of the initial condition. Pink dashed lines indicate the maximum percentage of orthogonal initial conditions that evoke response norm 50% larger than initial condition for WIE/WEE = 1.8 (lower percentage) and WIE/WEE = 0.4 (higher percentage).