IMAT 2017 Q32 [Memory Loss]

A person was admitted to hospital suffering from a loss of memory.

Which part of the central nervous system is most likely to have been affected?

A. cerebellum
B. spinal cord
C. medulla
D. cerebrum
E. hypothalamus

The correct answer is D.

Let’s review each item individually :

  1. The cerebellum, located at the back of the brain, plays a key role in posture, tone and balance. It is also important for the coordination of fine movements.

How does that work ? The cerebellum receives different proprioceptive information, which is information regarding the position and movement of the body. Through its connection to the spinal cord and brainstem, a motor command is generated. The movement is consistently regulated by corrective signals to ensure smooth and coordinated movement. It is NOT associated with memory.

  1. The spinal cord controls the body movements and reports senses to the brain. It is also the structure that generates reflexes.

How does that work ? A sensory stimuli is perceived by the sensory neuron (the receptor) and then sent to the spinal cord. An interneuron is the link between that sensory neuron and the motor neuron (the effector), which then generates the motor response. It is NOT associated with memory.

  1. The medulla oblongata is located at the lower part of the brain, and helps transfer information from the brain to the spinal cord. Most importantly, it controls life sustaining functions like the heart rate, blood pressure or breathing.

How does that work ? The nerve signals indicating the CO2 and pH levels on the aorta are sent to the medulla, which then triggers the contraction of intercostal muscles and the diaphragm, and inducing respiration. It is NOT associated with memory.

  1. The cerebrum is the biggest part of the brain. It is composed of 2 hemispheres. Among the structures it contains, the one that concerns us is the hippocampus, to which factual memory formation is attributed to. It is also associated with working memory. Therefore, item D is correct.

  2. The hypothalamus is a structure located deep inside the brain. Its main purpose is to maintain homeostasis in the body, and therefore is involved in activities such as drinking and eating, by controlling appetite and releasing hormones. It is NOT associated with memory.