Diverse synaptic plasticity mechanisms orchestrated to form and retrieve memories in spiking neural networks

TLDR

Synaptic plasticity, the basis of learning and memory, occurs in many forms and timescales. The study demonstrates that combining Hebbian homosynaptic, rapid non‑Hebbian heterosynaptic, slower homeostatic changes, and consolidation enables assembly formation and memory recall in a spiking recurrent network. The spiking recurrent network model forms assemblies through repeated sensory stimulation, producing strong recurrent excitatory connections. Memories persisted for days and were recalled through selective delay activity after brief stimulation, but blocking any plasticity component disrupted memory function, indicating that diverse plasticity mechanisms are coordinated to achieve common functional goals.

Abstract

Abstract Synaptic plasticity, the putative basis of learning and memory formation, manifests in various forms and across different timescales. Here we show that the interaction of Hebbian homosynaptic plasticity with rapid non-Hebbian heterosynaptic plasticity is, when complemented with slower homeostatic changes and consolidation, sufficient for assembly formation and memory recall in a spiking recurrent network model of excitatory and inhibitory neurons. In the model, assemblies were formed during repeated sensory stimulation and characterized by strong recurrent excitatory connections. Even days after formation, and despite ongoing network activity and synaptic plasticity, memories could be recalled through selective delay activity following the brief stimulation of a subset of assembly neurons. Blocking any component of plasticity prevented stable functioning as a memory network. Our modelling results suggest that the diversity of plasticity phenomena in the brain is orchestrated towards achieving common functional goals.