Synaptic and Ephaptic Proposals for Selective Attention: A Comparative Study

We compare two mathematical frameworks for understanding selective attention in neural systems: the synaptic-based Free Energy Principle of Friston, which posits that brains minimize prediction error through hierarchical Bayesian inference, and the ephaptic coupling framework of Chawla and Morgera, which demonstrates that electromagnetic field interactions between adjacent axons automatically amplify high-entropy signals. These approaches offer fundamentally different explanations for how nervous systems select salient stimuli. Friston’s framework requires complex computational cascades involving precision weighting, hierarchical revision, and widespread cortical recruitment. In contrast, ephaptic coupling provides a physical substrate whereby high-information-content signals automatically dominate through local electromagnetic interactions in axon tracts. We argue that ephaptic coupling may provide the physical mechanism underlying selective attention, operating at the substrate level rather than as an algorithmic process. The frameworks differ in their predictions regarding computational complexity, the role of top-down versus bottom-up processing, and whether the nervous system works to minimize or amplify entropy. We discuss empirical approaches to distinguish these proposals and consider whether they might be complementary rather than mutually exclusive.