The hypothalamus is involved in regulating several functions, which includes: maintaining homeostasis, body temperature, hunger, thirst, sexual drive, sleep, and mood. It does this by releasing hormones through the pituitary gland. The occipital lobe is the part of the brain that is involved in processing visual information.

Parkinson's disease is a degenerative disorder that affects the substantia nigra, among other nerve cells. This region is responsible for the production of dopamine, a neurotransmitter that facilitates smooth and coordinated body movements by allowing communication between the brain and muscles. When dopamine receptors related to movement are inadequately stimulated the result can be inhibitory, causing muscle rigidity and tremors. On the other hand, an overabundance of dopamine may produce symptoms of paranoia and psychosis as can be found in true schizophrenia. A deficiency in serotonin has been associated with depression, increased aggression, and overeating. Overly high serotonin levels on the other hand result in symptoms including confusion, a rapid heart-rate, agitation, and restlessness.

The "hippocampus," part of the brain's limbic system, plays an important role in the consolidation of information from short-term memory to long-term memory. In addition, the hippocampus helps with our spatial navigation.

The "cerebrum" is a large part of the brain containing the cerebral cortex, as well as several subcortical structures. The cerebrum is not located in the limbic system, while the other answer choices are.

The "medulla," also known as the medulla oblongata, contains the respiratory, cardiac, and vasomotor centers of the brain; therefore, the medulla controls the autonomic functions.  These functions include: breathing, heart rate, and blood pressure. We would be not be able to survive—not even for a minute—without a functioning medulla.

The "hypothalamus" is responsible for synthesizing and secreting neurohormones that stimulate the secretion of pituitary hormones. The hypothalamus controls many important bodily functions, including maintaining a healthy body temperature and circadian rhythm (i.e. our 24 hour internal cycle).

The "temporal lobe" plays an important role in organizing sensory input, auditory information, and language production. All four major lobes of the brain (temporal, parietal, frontal, and occipital) are located in the cerebral cortex.

The "cerebral cortex" is the large, folded exterior portion of the cerebrum that contains the different lobes of the brain. This structure is responsible for memory, perception, and consciousness—among other things. The fornix and the amygdala are part of the limbic system and do not play a large role in higher level thought. Additionally, the corpus callosum is anatomically defined simply as the connections between the two hemispheres of the brain. 

The parasympathetic nervous system (PSNS) is responsible for activating "rest and digest" and returning the body to equilibrium after a fight or flight response. This is opposed to the sympathetic nervous system (SNS) that is involved in the "fight or flight" response. They are both branches of the autonomic nervous system (ANS) which involuntarily regulates function of internal organs.

The corpus callosum is a band of nerve fibers that connect the brain's left and right hemispheres together. It is the largest white matter structure in the brain, and allows valuable information to be shared across brain hemispheres.