PLATE 3. Magnetic resonance imaging (MRI) is an invaluable tool in clinical practice today, as well as in neuroscientific research. Here, the crosssectional image of a patient's head clearly discloses the shape and location of a tumor (the egg-shaped yellow mass in the right hemisphere). Healthy brain tissue appears in gray, and the skull and scalp in pink. Such images contribute to precise diagnosis and, when necessary, the planning of neurosurgery.