Fig. 5: Mathematical models of the impact of CP-AMPAR removal on selectivity.

a, Feed-forward network architecture of a PV neuron (circle) receiving inputs from pyramidal cells (Pyr; triangles, n = 64). Insets depict tuning curves. b, Pyramidal–PV connectivity depends on the difference between the preferred orientation of the PV neuron and the pyramidal cell in question. c, Tuning of pyramidal and PV responses. OSI: 0.73 (Pyr) and 0.44 (PV). Rates are normalized by their maximum for visual comparison. d, Rate-dependent weight reduction as a model of CP-AMPAR-dependent inward rectification in control PV-Cre;lsl-eGFP neurons (magenta), parametrized by a maximum amplitude A and a midpoint M. The removal of CP-AMPARs and inward rectification in PV-Cre;Isl-eGFP-GluA2 mice is modelled by removing the rate dependence of the synaptic weights (green). e, Removal of CP-AMPARs decreases responses to non-preferred stimuli but not to preferred stimuli, thereby increasing stimulus selectivity. OSI with and without CP-AMPARs: 0.48 and 0.59, respectively. f, As for e, but normalized. g, Orientation selectivity increases for most combinations of amplification and midpoint. Dot shows the example shown in e and f (A = 1.6, M = 4). h, Bienenstock–Cooper–Munro plasticity rule. PV rates below the threshold cause LTD, whereas PV rates above the threshold cause LTP. Exaggerated LTD is modelled by increasing the threshold (magenta, 8 Hz; green, 12 Hz). i,j Increased LTD sharpens the pyramidal–PV connectivity (i) and increases PV selectivity (j). OSI with baseline and increased LTD: 0.58 and 0.69, respectively. k, Orientation selectivity increases with the threshold as long as this threshold is within the range of PV responses (between about 6 and 11 Hz).