Glioma is a term that is used to describe a group of tumors that arise from the glial cells that support the function of the other main brain cell type—the neuron. Gliomas usually happen in the cerebral hemispheres of the brain, the largest, outermost part of the brain that controls many functions that include movement, speech, thinking and emotions. They can also affect the brain stem, the lower part of the brain that controls functions like breathing, blood pressure and the heartbeat, as well as the optic nerves and cerebellum, a part of the brain that deals with balance and other non-thinking functions. Glioma tumors can be benign or malignant.