Neural network modulation, dynamics, and plasticity

Brain networks are unique in their capacity to modify synaptic structure while at the same time modulating neuronal firing properties. We investigated the interaction of these plastic network properties with overall network dynamics in large, biophysical neuronal network models. We modulated firing properties of individual neurons by simulating changing levels of acetylcholine (ACh), a key neurotransmitter whose level varies across waking and sleep states. When synaptic connection strengths were allowed to evolve according to a spike timing-dependent plasticity rule, results showed that ACh-induced changes in cellular properties led to different network activity patterns that resulted in either overall synaptic strengthening or weakening. These results suggest that the effect of ACh on neuron firing could contribute to hypothesized sleep-related synaptic renormalization in the brain.