The structured ‘low temperature’ phase of the retinal population code
Fig 10
The phase space of the retinal population code.
Sketches of the phase space of the nearest neighbor Ising ferromagnet (A), the Sherrington-Kirkpatrick model (B, following Fig.1 in Ref. [67]), and our work (C). Black lines indicate boundaries between phases which correspond to first-order phase transitions, while gray dots and gray lines correspond to transitions of higher-order (second- or third-order, depending on the model). Colored arrows indicate phase transitions of different orders. A. The line of first-order phase transitions is centered on an applied field h = 0, the critical point here is second-order. B. All transitions here are second-order, except in the spin glass limit, where they are third-order (the spin glass limit, μJ ≪ σJ, is denoted by the dotted line). As explained later on in the text, the second-order transitions here are marked by a discontinuity, not divergence, in the specific heat. C. In our work, a third-order phase transition as a function of correlation (at α = α*, T = 0) is the origin of a line of first-order phase transitions as a function of temperature. The location of the real neural population code is denoted by a star.