Adult neurogenesis, learning and memory

Abstract

An emerging view in Neuroscience is that cognitive functions such as learning and memory engage all the various cell types making-up the brain, including surveillant microglia, the resident immune cells. These complex functions prominently depend on the structural remodeling of neuronal circuits, rooted in the formation, strengthening, and elimination of synaptic structures, but also on the continuous integration of newborn neurons into the mature circuitry. In this chapter, we will focus our attention on the emerging roles of microglia in adult neurogenesis within its two consensus regions, the hippocampus and the olfactory bulb. We will discuss the underlying cellular and molecular mechanisms based on evidence from both inflammatory and non-inflammatory conditions. Doing so, we will also examine their implications for learning and memory, and the effects of environmental enrichment, running paradigms, normal aging, and neurodegenerative diseases on microglia, adult neurogenesis, and the behavioural outcome. Lastly, we will summarize the key points that emerge from our current understanding of these new roles of microglia in adult neurogenesis, learning and memory, and the most promising directions to pursue in this recent field of investigation.