We thank Udi Karpas, Roy Harpaz, Tal Tamir, Adam Haber, and Amir Bar, for discussions and suggestions, and especially Oren Forkosh and Walter Senn, for invaluable discussions of the learning rule. This work was supported by a European Research Council Grant 311238 (ES), an Israel Science Foundation Grant 1629/12 (ES), research support from Martin Kushner Schnur and Mr. and Mrs. Lawrence Feis (ES), IMH grant R01MH109180 (RS), Simons Collaboration on the Global Brain grant 542997 (RK and ES), Pew Scholarship in Biomedical Sciences (RK), and a CRCNS grant (ES and RK). Author contributions: O.M., G.T., R.K., and E.S. designed research; O.M., G.T., M.S.E., R.K., and E.S. performed research; O.M., G.T., R.K., and E.S. analyzed data; and O.M., G.T., R.K., and E.S. wrote the paper.