What Do Microglia Really Do in Healthy Adult Brain?

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Microglia, originating from yolk sac-primitive macrophages, self-renew throughout adulthood.
• While their role in brain pathology is well-studied, their function in the healthy adult brain remains less understood.
• Astrocytes and oligodendrocytes are recognized for maintaining brain homeostasis and modulating neuronal function.

Purpose of the Study:

• To explore the underappreciated role of microglia in the healthy adult brain.
• To reposition microglia as key contributors to cognitive processes and brain homeostasis.
• To highlight emerging evidence on microglia's influence on adult neurogenesis.

Main Methods:

• Review of existing literature on microglia function.
• Analysis of studies utilizing microglial depletion assays and conditional mutants.
• Examination of research investigating microglia's impact on cognition, learning, and neurogenesis.

Main Results:

• Absence of microglia can lead to developmental cognitive deficits, with less pronounced effects in adults.
• Emerging evidence indicates microglia significantly influence adult cognition, learning, and potentially adult neurogenesis.
• Microglia actively contribute to maintaining brain homeostasis in healthy adults.

Conclusions:

• Microglia are essential for maintaining brain homeostasis and cognitive function in healthy adult brains.
• Their role extends beyond neuroinflammation to actively support brain health and learning.
• Further research is needed to fully elucidate the multifaceted functions of microglia in the adult brain.