Multi-contact synapses for stable networks: a spike-timing dependent model of dendritic spine plasticity and turnover

TL;DR

This paper introduces a combined spike-timing dependent plasticity and turnover model explaining the stable multi-contact synapses in adult neocortex, emphasizing the importance of contact cooperation for long-term memory stability.

Contribution

It presents a novel model integrating dendritic spine plasticity and turnover, aligning with experimental data and explaining stable multi-contact synaptic configurations.

Findings

Model reproduces long-term dendritic spine dynamics.

Cooperation of multiple contacts stabilizes synaptic memory.

Simulates whisker-trimming induced rewiring in cortex.

Abstract

Excitatory synaptic connections in the adult neocortex consist of multiple synaptic contacts, almost exclusively formed on dendritic spines. Changes of dendritic spine shape and volume, a correlate of synaptic strength, can be tracked in vivo for weeks. Here, we present a combined model of spike-timing dependent dendritic spine plasticity and turnover that explains the steady state multi-contact configuration of synapses in adult neocortical networks. In this model, many presynaptic neurons compete to make strong synaptic connections onto postsynaptic neurons, while the synaptic contacts comprising each connection cooperate via postsynaptic firing. We demonstrate that the model is consistent with experimentally observed long-term dendritic spine dynamics under steady-state and lesion induced conditions, and show that cooperation of multiple synaptic contacts is crucial for stable, long-term synaptic memories. In simulations of a simplified network of barrel cortex, our plasticity rule reproduces whisker-trimming induced rewiring of thalamo-cortical and recurrent synaptic connectivity on realistic time scales.