Brain plasticity, or neuroplasticity, is the lifelong ability of the brain to change. Plasticity mechanisms mediate development, memory, learning, adaptation to changing sensory environments, and compensation for loss of function. However, experience-dependent plasticity mechanisms—maladaptive plasticity—can also cause symptoms and signs of disease.Mechanisms of synaptic plasticity have traditionally been ascribed to higher-order sensory processing areas such as the cortex, whereas early sensory processing centers have been considered largely hard-wired. However, recent results from the Tzounopoulos laboratory and other studies have revealed remarkable evidence of cellular and behavioral mechanisms for learning and memory in the early stages of sensory processing. Tzounopoulos investigates the cellular mechanisms underlying synaptic and intrinsic plasticity in sensory systems and their role in normal and pathological sensory processing. One focus of his research is the underlying cellular mechanisms of tinnitus (the perception of sound in the ears or head where no external source is present), with the goal of understanding the maladaptive plasticity mechanisms involved in the development of the disorder.