Backprop Alternative: Augmented Lagrangian Predictive Coding

PC-ALM is a new training method for deep neural networks that works as a local alternative to backpropagation. Unlike backpropagation, which requires strict coordination across an entire network, PC-ALM gives each layer its own feedback control system, allowing credit signals to spread without global coordination. It successfully trained 1,000-layer networks while nearly matching backpropagation's performance, something previous local methods struggled to achieve. The research could also help explain how the brain learns without backpropagation.