Which of the following is NOT found in the human central nervous system?

A) hypothalamus
B) forebrain (cerebrum)
C) autonomic neurons
D) medulla
E) spinal cord

To answer this question, we need to understand what the human central nervous system (CNS) is and what structures are a part of it. The CNS consists of the brain and the spinal cord, which play crucial roles in receiving, interpreting, and sending information throughout the body.

Let's go through each option and determine if it is found in the human CNS:

A) hypothalamus: The hypothalamus is a small region located in the forebrain and is a vital part of the CNS. It helps regulate various physiological processes such as body temperature, hunger, thirst, and hormone production. Therefore, the hypothalamus is present in the human CNS.

B) forebrain (cerebrum): The forebrain, specifically the cerebrum, is the largest and most highly developed part of the human brain. It is responsible for many complex functions, including sensory processing, motor control, reasoning, and memory. Hence, the forebrain is found in the human CNS.

C) autonomic neurons: Autonomic neurons are a specific type of nerve cells that are responsible for regulating involuntary bodily functions such as heart rate, digestion, and respiration. These neurons are present in the autonomic nervous system, which is a division of the peripheral nervous system and not a part of the central nervous system. Therefore, autonomic neurons are NOT found in the human CNS.

D) medulla: The medulla, also known as the medulla oblongata, is located at the base of the brainstem. It controls essential functions like breathing, heart rate, and blood pressure. Since it is a part of the lower portion of the brainstem, the medulla is indeed found in the human CNS.

E) spinal cord: The spinal cord is a long, thin bundle of nerves that runs down the vertebral column. It is a crucial component of the CNS as it serves as a pathway for transmitting sensory and motor signals between the brain and the rest of the body. Therefore, the spinal cord is undoubtedly found in the human CNS.

To summarize, the structure that is NOT found in the human CNS is C) autonomic neurons.