Backpropagation destroys V1 brain alignment in one epoch, tracking RSA alignment to fMRI across training for BP, FA, predictive coding, and STDP [R]

In three linesComparative study of learning rules (backprop, feedback alignment, predictive coding, STDP) via RSA alignment with human V1 fMRI. Backprop destroys 90% of V1 alignment after 1 epoch (r: 0.102→0.011), while PC and STDP lose only 25-31%. At epoch 40: PC/STDP >> BP/FA. Suggests fundamental trade-off between global error signals (higher layers) and early-layer alignment.

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