The different cellular mechanisms that govern complex brain functions are regulated through intrinsic (genetic) or external (environmental) factors. One of the most critical regulatory axes at the cellular level is established around the cellular capacities that counteract the oxidative stress emerging in different pathophysiological contexts. At the brain level, this control is essential due to the limited capacity of neurons in forming new cells. Therefore, brain cells cope very efficiently with oxidative stress, and their functions are only altered when these cellular strategies are overwhelmed. This reprint contains original research and review articles on the regulation of cellular processes where antioxidant defenses are essential for maintaining the normal functioning of brain cells, including different cellular signaling mechanisms and their dysfunction.