Neuroscience is the study of the brain and the nervous system. If you're interested in the way human brains work, you might want to study neuroscience.
The scientific field of neuroscience started out as a branch of biology, although people have been fascinated with the brain at least since ancient Egyptians studied the effects of drilling small holes in the skull to treat mental disorders. Today neuroscience is an interdisciplinary field, involving chemistry, linguistics, and genetics, among many other disciplines. Neuroscience has roots in the Greek neuro, "nerve," and Latin scientia, "knowledge."