Evolving to learn: discovering interpretable plasticity rules for spiking networks

• DOI: 10.48550/arxiv.2005.14149
• Publication Date: 2020-01-01
• Authors: Jordan, Jakob; Schmidt, Maximilian; Senn, Walter; Petrovici, Mihai A.
• Keywords: 0301 basic medicine; Computational Neuroscience; 0303 health sciences; 03 medical and health sciences; Quantitative Biology - Neurons and Cognition; FOS: Biological sciences; Neurons and Cognition (q-bio.NC); Learning, plasticity and memory

Continuous adaptation allows survival in an ever-changing world. Adjustments in the synaptic coupling strength between neurons are essential for this capability, setting us apart from simpler, hard-wired organisms. How these changes can be mathematically described at the phenomenological level, as so called "plasticity rules", is essential both for understanding biological information processing and for developing cognitively performant artificial systems. We suggest an automated approach for discovering biophysically plausible plasticity rules based on the definition of task families, associated performance measures and biophysical constraints. By evolving compact symbolic expressions we ensure the discovered plasticity rules are amenable to intuitive understanding, fundamental for successful communication and human-guided generalization. We successfully apply our approach to typical learning scenarios and discover previously unknown mechanisms for learning efficiently from rewards, recover efficient gradient-descent methods for learning from target signals, and uncover various functionally equivalent STDP-like rules with tuned homeostatic mechanisms.<br/>33 pages, 10 figures; J. Jordan and M. Schmidt contributed equally to this work<br/>