All Questions: 1-30

Correct answer: B

The optic disc is a part of the retina where the axons of retinal ganglion cells leave the eye to form the optic nerve. The optic disc lacks photoreceptors, thus creating a small "blind spot" in our visual field. We do not typically notice the blind spot because the brain uses information from the other eye to make the visual scene appear intact.

Correct answer: A

The word "hippocampus" comes from the Greek word for "seahorse." It earned this name because when you remove the hippocampus from the brain, it vaguely resembles a seahorse.

Correct answer: B

A healthy plantar reflex involves the toes curling downwards. If the big toe extends and the other toes fan out, this is known as the Babinski sign. If it occurs in adults, it can be indicative of nervous system damage/dysfunction, often involving the corticospinal tract. The Babinski sign, however, is normal in infants. Some individuals may not respond to plantar stimulation; this is known as a "neutral" response. It doesn't necessarily indicate a problem, but may warrant further investigation.

Correct answer: C

After sodium (Na+) has rushed into the cell in the rising phase of the action potential, the sodium channels close and potassium (K+) begins to leave the cell. This brings the neuron back to its resting membrane potential. The potassium channels, however, close gradually and allow enough positively-charged potassium to leave the neuron that the cell becomes briefly hyperpolarized. This creates a "relative refractory period," when it's less likely for the neuron to fire another action potential.

Correct answer: D

Capgras syndrome is a rare condition where patients begin to believe that people close to them (e.g., spouse, parents, children) have been replaced by imposters who look and act just like their loved ones. The delusions can also extend to individuals who are not close to the patient, and over time Capgras patients often begin to identify an increasing number of imposters in their life.

Correct answer: A

The corneal eye blink reflex tests the integrity of the trigeminal & facial nerves. The trigeminal nerve is the sensory limb of the reflex & the facial nerve controls the blinking of the eyes. The healthy response to touching one cornea would be that both eyes would blink. In Malik’s case, both facial nerves are functional as indicated by his healthy response to touching his left eye. When his right eye is touched, neither eye blinks, which suggests a problem with his right trigeminal nerve.

Correct answer: C

The hypothalamus is connected to the anterior pituitary gland via a network of blood vessels called the hypophyseal portal system. The hypothalamus secretes a releasing hormone into the hypophyseal portal system, and the releasing hormone binds to receptors on anterior pituitary cells, prompting the release of a specific hormone from the anterior pituitary into the bloodstream in response.

Correct answer: C

The functions indicated in the answer choices are associated with three tracts: the spinothalamic tract (pain/temperature), dorsal columns-medial lemniscus (touch/proprioception), & corticospinal tract (movement). Damage to half of the spinal cord would disrupt all three pathways, but the deficit for the dorsal columns-medial lemniscus and corticospinal tract would be on the same side, while the spinothalamic tract deficit would be on the opposite side, due to where these tracts decussate.

Correct answer: B

The doctor assumed the left cerebral hemisphere was involved due to the patient's inability to move her right arm and leg. Voluntary movement of the right side of the body is primarily controlled by signals that descend from the left cerebral hemisphere, and vice versa.

Correct answer: C

The abducens nerve controls the lateral rectus muscle, which moves the eye laterally (i.e., to the side). When there is damage to the abducens nerve, a patient will often display an inability to move the eye laterally, and when they look straight ahead the eye will deviate medially because of the unopposed action of the medial rectus muscle (which moves the eye medially). There are a number of potential reasons for abducens nerve damage, including trauma, tumors, stroke, infections, and others.

Correct answer: D

Rapid eye movement, or REM, sleep is sometimes called paradoxical sleep because the brain activity observed during REM resembles what is seen when someone is awake. During REM sleep, the muscles are completely relaxed and limp but the eyes are moving rapidly. This is also the time of sleep when our most vivid dreams are likely to occur.

Correct answer: C

The oculomotor nerve controls the function of four of our extraocular muscles as well as the muscle that raises the eyelid and the muscle that constricts the pupil. When the oculomotor nerve is damaged, the collection of symptoms in the question often occurs.

Correct answer: D

The corpus callosum is the largest collection of white matter in the brain. It connects the two cerebral hemispheres and permits communication between them. A corpus callosotomy is a procedure where the corpus callosum is severed (typically partially), and it can be done to reduce the ability of seizures to spread from one cerebral hemisphere to the other. See this article for more info:

Correct answer: B

While turkey does contain tryptophan, it doesn't have higher levels of tryptophan than many other foods such as chicken, cheese, etc. While it is often claimed that eating a lot of turkey (e.g., on Thanksgiving) can increase tryptophan levels to the point of causing sleepiness, the tryptophan in turkey is not thought to contribute substantially to fatigue. It's more likely that tiredness after a large turkey meal is due to other factors, such as typical post-meal lethargy, alcohol intake, etc.

Correct answer: D

Myelin is an insulating material that covers the axons of most neurons in the nervous system. Oligodendrocytes are the cells responsible for myelinating central nervous system neurons, while Schwann cells myelinate neurons in the peripheral nervous system.

Correct answer: A

The facial nerve controls the muscles of facial expression, and facial nerve dysfunction can cause the symptoms Rebecca is experiencing. When these types of symptoms occur in someone who is otherwise healthy (and thus there is no clear cause of the symptoms), the diagnosis is often Bell's palsy. Bell's palsy involves facial nerve dysfunction with an unknown origin. The symptoms typically come on rapidly, but also usually resolve on their own within several months.

Correct answer: D

Parkinson's disease (PD) is a neurodegenerative disease, meaning it is characterized by the degeneration and death of neurons. While neuronal death in PD can occur in various brain areas, the substantia nigra is most affected. The substantia nigra is a region in the brainstem that is rich in dopamine neurons; these neurons are thought to play important roles in facilitating movement. By the time a PD patient dies, they may have lost up to 70% of the dopamine neurons in their substantia nigrae.

Correct answer: A

Synapses can be formed between any two components of a neuron, but most of a neuron's synapses are found at its dendrites. This is where a neuron receives most of its incoming messages in the form of neurotransmitters and other signaling molecules.

Correct answer: B

Broca's aphasia is characterized by a deficit in the ability to produce language, but language comprehension is typically intact. Broca's aphasia was named for its association with damage to Broca's area, a region of the brain implicated in language production, but it can result from damage to other areas of the brain as well.

Correct answer: D

Ataxia involves impaired coordination of movement. It can have a variety of causes, but one region often implicated in ataxia is the cerebellum. The cerebellum is involved in many movement-related functions, including coordinating movement and maintaining balance. Thus, when there is cerebellar dysfunction (e.g., due to stroke), ataxia is a common result. For more info, see this article:

Correct answer: C

Hydrocephalus is a condition that involves the accumulation of cerebrospinal fluid (CSF) in the ventricles. It can occur due to excess production of CSF, impaired reabsorption of CSF into the bloodstream, or a blockage in the ventricular system that causes CSF to accumulate.

Correct answer: D

Neurons primarily release the neurotransmitter acetylcholine to cause contraction of skeletal muscle. Acetylcholine then binds to receptors in the muscle membrane to cause muscle contraction.

Correct answer: C

Gray matter is characterized by having a high amount of neuronal cell bodies and fewer myelinated axons. White matter has a high amount of myelinated axons, which give it its white(ish) color.

Correct answer: C

The spinothalamic tract, which is part of the larger anterolateral pathway in the spinal cord, is the main pathway for carrying pain and temperature information to the brain.

Correct answer: B

Upon binding to a receptor, GABA can cause the opening of an ion channel that is permeable to negatively charged chloride (Cl-) ions. When these negatively charged ions flow into the neuron, they cause the neuron to become slightly hyperpolarized. Thus, the neuron is less likely to fire an action potential, and GABA has had an inhibitory effect.

Correct answer: A

The sympathetic division of the autonomic nervous system is most active during threatening situations, or any situation that requires increased activity of the body. It is involved in what are sometimes called "fight-or-flight" reactions (like Robert was displaying). It increases heart rate and blood flow to muscles to enable them to act, among other functions.

Correct answer: A

The thalamus is sometimes called a "relay station" because it is an important hub in many circuits that carry information to and from the cerebral cortex, and it is a stopping off point for all sensory information (except olfactory information) before that info gets sent to the cortex. The thalamus is much more than just a relay station, though, as it is involved in processing information as well.

Correct answer: C

The suprachiasmatic nucleus is a nucleus in the hypothalamus that contains cells that act as the circadian pacemaker of mammals. The cells "keep time" through a process of gene transcription, protein production, and protein degradation that takes approximately 24 hours to complete.

Correct answer: B

The small bumps that cover the tongue are sometimes mistakenly called taste buds, but the correct term for them is papillae. Taste buds are found in the walls of the papillae, with each papilla containing anywhere from a just a few to hundreds of taste buds. Each taste bud contains 50-150 taste receptor cells, which interact with the substances in the mouth through microvilli that extend into the mouth.

Correct answer: B

Dopamine is available in drug form, and is used in certain situations (e.g., low blood pressure) in medical settings. Dopamine, however, cannot cross the blood-brain barrier (BBB). Thus, if given to Parkinson's patients, it never makes it to the brain. This is why we often use L-DOPA to treat Parkinson's disease, as it can cross the BBB and the brain can use it to make more dopamine.