Predictive Coding with Bayesian Priors via Proximal Gradients
Summary
A new theoretical framework recasts predictive coding as continuous-time proximal gradient descent applied to a regularized maximum-a-posteriori (MAP) objective. For single-level problems, this approach demonstrates that proximal gradient descent precisely describes a leaky firing-rate network, where elements like membrane leak, recurrent matrix, and synaptic drive derive from a single optimization principle, aligning with Rao and Ballard's circuit. The prior determines the network's nonlinearity via its proximal operator, while likelihood precision sets observation gain. For multi-level hierarchies, a classical variable-splitting relaxation of the deep MAP problem yields hierarchical predictive coding, connecting local and distributed solvers by transforming the directed generative chain into an undirected Markov random field.
Key takeaway
For AI scientists researching biologically plausible learning or neural network dynamics, this framework offers a unified optimization perspective on predictive coding. You should consider how this reinterpretation, linking network components to a MAP objective via proximal gradients, could inform the design or analysis of hierarchical generative models, potentially simplifying their theoretical underpinnings and implementation.
Key insights
Predictive coding is reinterpreted as continuous-time proximal gradient descent on a regularized maximum-a-posteriori objective.
Principles
- Network components derive from one optimization principle.
- Prior selects nonlinearity via its proximal operator.
- Likelihood precision sets observation gain.
Method
Recasts predictive coding as continuous-time proximal gradient descent on a regularized MAP objective, employing variable-splitting relaxation for hierarchical structures.
Topics
- Predictive Coding
- Bayesian Priors
- Proximal Gradient Descent
- MAP Objective
- Neural Networks
- Markov Random Fields
Best for: Research Scientist, AI Scientist
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Editorial summary, takeaway, and curation by AIssential. Original article published by Machine Learning.