Astrocytes: The Rising Stars that Regulate Synaptic Plasticity and Long-Term Memory Formation

For decades, our understanding of the mechanisms underlying long-term synaptic plasticity and memory is largely limited to the roles played by neuronal elements. Astrocytes, the most abundant glia cells in the brain, were merely assumed to play supportive roles for neurons, with little role in information computing. With the advent of newly developed tools such as mouse genetics and dynamic cellular imaging techniques that allow astrocyte-specific interrogations, emerging evidence reveals unrecognized functions of astrocytes, leading to the idea that synaptic plasticity and memory formation result from the coordinated action of neuron-glia networks. Remarkably, astrocytes could decode neural activity with elaborate Ca2+ dynamics, which in turn triggers the release of neuroactive molecules to drive synaptic plasticity and memory formation. This chapter will describe and discuss the emerging roles of astrocytes in synaptic plasticity and memory and the cellular underpinnings of their functions, focusing on their regulatory effects on long-term synaptic plasticity and memory, to match the context of this book. It is hoped that this chapter serves as a primer to probe in further role of astrocytes in regulating specific aspects of synaptic tagging and capture (STC).