Brain. Wire-frame computer image of a side view of a healthy human brain. The front of the brain is at left. From top to centre is one of the hemispheres of the cerebrum, which is responsible for conscious thought, emotion and voluntary movement. At lower right at the base of the brain is the cerebellum, which controls voluntary muscular movement and maintains posture and balance. At bottom centre is the brainstem, which controls subconscious functions such as breathing and the regulation of heart rate. It also connects the brain to the spinal cord.