Spectrum and collective modes of fluctuations in a heterogeneous population.

<p>(A) Eigenvalue spectrum of the spike count correlation matrix of a heterogeneous pseudo-population containing all 30 neurons in our data set, and input correlations of and . The inset shows the largest eigenvalue (circle) and mean of all other eigenvalues (diamond) as function of population size. (B) The different eigenvectors of the spike-count correlation matrix ( and ) are shown by different colors. The thick blue line depicts the eigenvector with the largest eigenvalue.