associated with mood, reward, and addiction periaqueductal gray matter (PAG) a region surrounding the cerebral aqueduct in the core of the midbrain, with descending pathways that can inhibit the transmission of pain-causing signals tectum a part of the midbrain that orients an organism in the environment tegmentum ventral part of the midbrain; includes the periaqueductal gray matter, reticular formation, red nucleus, and substantia nigra; involved in movement and arousal hindbrain medulla, pons, cerebellum pons brain structure that relays information from the cerebellum to the rest of the brain cerebellum the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance medulla the base of the brainstem; controls heartbeat and breathing frontal lobe The lobe at the front of the brain associated with movement, speech, and impulsive behavior; higher cognitive function temporal lobe area on each hemisphere of the cerebral cortex near the temples that is the primary receiving area for auditory information parietal lobe portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position occipital lobe region of the cerebral cortex towards the rear back that processes visual information primary motor cortex the section of the frontal lobe responsible for voluntary movement primary sensory cortex regions of the cerebral cortex that initially process information from the senses somatosensory cortex primary sensory cortex in the parietal lobe that registers and processes body touch and movement sensations auditory cortex the area of the temporal lobe responsible for processing sound information visual cortex visual processing areas of cortex in the occipital (and temporal) lobes association cortex regions of the cerebral cortex that integrate simpler functions to perform more complex functions; in all lobes; 90% of cerebral cortex cerebrum largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory