In Frontiers of Computational Neuroscience, members of INCF Indian Node suggest that cell groups in the CA3-CA1 network robustly follow a consistent set of linear summation and gain-control rules, notwithstanding the intrinsic non-linearities of individual neurons. Cell-group responses remain linear, with well-defined transformations following inhibitory modulation and plasticity. The measures of these transformations provide useful parameters to apply to neural network analyses involving modulation and plasticity.