Microglial Equilibrium in Brain Function and Dysfunction

Abstract

Microglia, the neuroimmune cells of the central nervous system (CNS), play a crucial role in brain development, health, and disease. Initially thought to be "resting,” they're now known to be highly active, constantly monitoring the brain tissue with their ramified processes to detect small changes in electrical balance, communication between nerve cells, or cell health. Through this constant vigilance, microglia control the removal of excess connections between nerve cells, fine-tune the brain's connections, provide nutrients and energy to cells, and coordinate the body's response to injury or infection. Their interactions with nerve cells, astrocytes, and oligodendrocytes further connect them to the larger network of brain cells that helps keep the brain in balance. However, when microglial regulation goes awry, these same functions can contribute to disease, including nerve cell loss, mental health disorders, brain injury, and autoimmune diseases. This review brings together the latest findings in microglial biology, focusing on their origins, surveillance methods, roles in nerve cell connections, metabolic control, and communication with other brain cells. Together, these insights show that microglia are both protectors of brain function and potential triggers of disease, putting them at the centre of brain health.