All Questions: 391-420
391. In which part of the brainstem are the superior and inferior colliculi found?
- A. midbrain
- B. pons
- C. medulla
Show Answer
Correct answer: A
The superior and inferior colliculi are found in the midbrain; their locations are marked by four bumps on the posterior surface of the brainstem. The superior colliculi are involved in eye movements and visual processing, while the inferior colliculi are involved in auditory processing.
392. Which area of the primary somatosensory cortex receives the most direct sensory input from the thalamus?
- A. area 1
- B. area 2
- C. area 3
- D. area 4
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Correct answer: C
The primary somatosensory cortex is typically divided into 3 areas: area 3 (which is often subdivided into area 3a and 3b), 1, and 2. Area 3 receives the majority of somatosensory input directly from the thalamus, and the initial processing of information occurs here.
393. This is the typically the most severe form of spina bifida; it can result in complications and disability:
- A. spina bifida occulta
- B. meningocele
- C. myelomeningocele
- D. spina bifida pernicia
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Correct answer: C
Spina bifida is a birth defect that involves disrupted formation of a structure called the neural tube. There are three types of spina bifida: myelomeningocele, meningocele, and spina bifida occulta. The latter two forms do not typically cause any symptoms. Myelomeningocele is typically the most severe form, and is more likely to result in complications and/or disability.
394. After a large holiday meal, you relax on the couch and watch a movie. Which of the following divisions of your nervous system would be most active during this period of relaxation?
- A. sympathetic nervous system
- B. parasympathetic nervous system
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Correct answer: B
The parasympathetic division promotes “rest and digest” functions (e.g., lowering heart rate and supporting digestion) while the sympathetic division handles “fight or flight.” While you're relaxing on the couch, your parasympathetic nervous system would be more active.
395. Why is red-green color blindness much more common in males than females?
- A. males have fewer cone photoreceptors than females
- B. testosterone interferes with the formation of red and green cones
- C. greater light exposure in males damages red and green cones during development
- D. causative mutations are on the X chromosome and males only have one X chromosome
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Correct answer: D
Red-green color blindness is much more common in males because the mutations that typically cause it are found on the X chromosome. If females possess such a mutation on one X chromosome, it is likely to be balanced out by a functional gene on the other X chromosome. Because males only have one X chromosome, a mutation is more likely to result in color blindness.
396. Which of the following is an accepted mechanism underlying tinnitus?
- A. a complete suppression of activity in the auditory cortex
- B. increased auditory pathway signaling to compensate for reduced cochlear input
- C. abnormal vibration of the tympanic membrane causing persistent sound perception
- D. excessive activation of vestibular hair cells
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Correct answer: B
The mechanisms underlying tinnitus are not well understood, and likely vary from case to case. One mechanism, however, is thought to involve damage to the cochlea, which may lead to increased signaling in other auditory structures to compensate for the reduction in auditory input from the cochlea. The resultant amplification of neural noise may lead to tinnitus.
397. Where do most of the fibers in the corticospinal tract decussate (i.e., cross to the other side of the nervous system)?
- A. in the medulla
- B. in the pons
- C. in the midbrain
- D. in the spinal cord
Show Answer
Correct answer: A
The upper motor neurons of the corticospinal tract leave the motor cortex and descend to the brainstem, continuing down into the medulla where the fibers form two bundles, known as the pyramids. At the base of the pyramids, about 90% of the fibers in the corticospinal tract decussate, or cross to the other side of the brainstem in a bundle called the pyramidal decussation.
398. This region of the retina has a high density of cones and is responsible for our highest acuity vision:
- A. optic disc
- B. sclera
- C. fovea
- D. peripheral retina
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Correct answer: C
The fovea represents the area of the retina that provides our highest acuity vision. It has a high density of cones and very few rods.
399. Where does the pineal gland get its name?
- A. it was first discovered by a scientist with the last name Pineal
- B. it resembles a pine cone in shape
- C. it is located near the pineal nerve
- D. it releases pinealocytes, which are shaped like pine needles
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Correct answer: B
The pineal gland is named for its pine cone-like shape.
400. The absolute refractory period of an action potential is primarily caused by which of the following?
- A. voltage-gated sodium channels becoming inactivated
- B. decreased sodium concentration outside the neuron
- C. breakdown of neurotransmitters in the synaptic cleft
- D. failure of ligand-gated ion channels to open
Show Answer
Correct answer: A
For a brief period after the initiation of an action potential, voltage-gated sodium channels become unresponsive and can't be activated. We call this period the absolute refractory period because a neuron will not be able to fire another action potential during this phase.
401. Which of the following is a main input area of the basal ganglia?
- A. substantia nigra pars reticulata
- B. internal globus pallidus
- C. nucleus basalis of Meynert
- D. striatum
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Correct answer: D
Much of the information the basal ganglia receive comes from the cerebral cortex and travels first to the striatum, which is a main input area of the basal ganglia. The main output nuclei of the basal ganglia are the internal globus pallidus and the substantia nigra pars reticulata, which send projections out of the basal ganglia to the thalamus as well as to nuclei in the brainstem.
402. Each section of myelination on an axon is called a/an:
- A. node of Ranvier
- B. neurofibril
- C. axon hillock
- D. internode
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Correct answer: D
Sections of myelin on an axon are called internodes. The gaps between internodes are called nodes of Ranvier.
403. Which of the following regions of the cerebellum is most involved in controlling posture?
- A. lateral hemisphere
- B. primary fissure
- C. superior cerebellar peduncle
- D. vermis
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Correct answer: D
The vermis runs along the midline of the cerebellum, and is especially involved in controlling upright posture. It receives input from the vestibular system and spinal cord and helps to regulate the muscles of the trunk that maintain posture.
404. The ganglia of the parasympathetic nervous system are typically found:
- A. in a chain that runs alongside the spinal cord
- B. in the dorsal root ganglia
- C. in or very near the walls of the organs they supply
- D. in the cerebral cortex
Show Answer
Correct answer: C
The parasympathetic ganglia are typically found near or in the wall of the organs they supply. The sympathetic ganglia, on the other hand, are typically found much closer to the spinal cord.
405. During which of the following activities would the default mode network be most likely to show its strongest activation?
- A. quiet rest with eyes closed while letting your mind wander
- B. tracking a moving dot on a screen and keeping a cursor centered on it
- C. doing rapid mental arithmetic under time pressure
- D. answering questions in a job interview
Show Answer
Correct answer: A
Default mode network is a term used to describe interconnected regions of the brain that display suppressed activity during cognitively demanding tasks focused on external stimuli, and higher activity during states of quiet wakefulness and when someone engages in internally focused thought such as daydreaming or the recall of personal experiences.
406. A woman sustains a spinal cord injury that completely damages the right half of her cervical spinal cord at C6. Which of the following deficits would she most likely exhibit?
- A. loss of pain and temperature sensation on the right side below the injury
- B. loss of tactile discrimination on the right side below the injury
- C. weakness or paralysis on the left side below the injury
- D. loss of proprioception on the left side below the injury
Show Answer
Correct answer: B
Damage to the right half of the spinal cord disrupts the dorsal column pathway (which is responsible for tactile discrimination, vibration, pressure, and proprioception) before it decussates, leading to loss of these sensations on the right (ipsilateral) side below the injury.
407. What is the most common neurodegenerative disease?
- A. Alzheimer's disease
- B. Parkinson's disease
- C. multiple sclerosis
- D. Huntington's disease
Show Answer
Correct answer: A
Alzheimer's disease is the most common neurodegenerative disease. It affects around 55 million people in the world, and accounts for roughly 60-70% of all cases of dementia.
408. During early neural development, the prosencephalon gives rise to which secondary vesicles?
- A. mesencephalon and metencephalon
- B. diencephalon and telencephalon
- C. metencephalon and myelencephalon
- D. diencephalon and mesencephalon
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Correct answer: B
The prosencephalon forms the diencephalon and telencephalon. The telencephalon will become the cerebral hemispheres, and the diencephalon will eventually consist of the thalamus, hypothalamus, epithalamus, and subthalamus.
409. The inability of a neuron to generate another action potential during the absolute refractory period is primarily due to:
- A. closure of voltage-gated potassium channels
- B. reduced neurotransmitter release at the synapse
- C. temporary failure of the sodium–potassium pump
- D. inactivation of voltage-gated sodium channels
Show Answer
Correct answer: D
For a brief period after the initiation of the action potential, voltage-gated sodium channels become unresponsive and can’t be activated. We call this period the absolute refractory period, because a neuron will not be able to fire another action potential during this phase.
410. Chemical signaling between neurons alters membrane potential through receptor activation. In which neuronal region does this process most commonly occur?
- A. dendrite
- B. axon
- C. nucleus
- D. synaptic boutons
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Correct answer: A
Chemical signaling between neurons most commonly occurs at synapses on the dendrites, where neurotransmitters bind to receptors and alter membrane conductance. These receptor-mediated changes produce graded potentials that influence whether the neuron will generate an action potential.
411. A patient suffers a stroke and afterward is able to speak fluently, but her speech consists largely of nonsensical and made-up words. She also has significant difficulty understanding spoken language. What is this type of language disorder called?
- A. global aphasia
- B. Wernicke's aphasia
- C. anomic aphasia
- D. Broca's aphasia
Show Answer
Correct answer: B
Wernicke’s aphasia is characterized by fluent but meaningless speech, often containing made-up or inappropriate words, along with impaired comprehension of spoken language. It is most commonly associated with damage to Wernicke’s area, often due to stroke.
412. The most well-characterized mechanism underlying long-term depression (LTD) involves the removal of which receptors from the neuronal cell membrane?
- A. NMDA receptors
- B. GABA_A receptors
- C. AMPA receptors
- D. Dopamine D1 receptors
Show Answer
Correct answer: C
During long-term depression (LTD), AMPA receptors are removed from the postsynaptic membrane, which reduces the strength of synaptic transmission. This trafficking is a key cellular mechanism for weakening specific synapses and is central to synaptic plasticity and learning processes.
413. Which of the following is the primary mechanism by which serotonin is removed from the synaptic cleft?
- A. diffusion into the postsynaptic neuron
- B. active transport into glial cells
- C. enzymatic breakdown by monoamine oxidase (MAO) in the synaptic cleft
- D. reuptake into the presynaptic neuron via the serotonin transporter
Show Answer
Correct answer: D
Serotonin is primarily removed from the synaptic cleft by a transport protein called the serotonin transporter, or SERT.
414. The HPA axis involves a cascade of hormones that results in the release of cortisol from the adrenal glands. What is the first hormone in the cascade?
- A. corticotropin-releasing hormone (CRH)
- B. corticosterone
- C. adrenocorticotropic hormone (ACTH)
- D. beta-endorphin
Show Answer
Correct answer: A
When we experience something stressful, the hypothalamus releases a hormone called corticotropin-releasing hormone (or CRH). This starts the cascade by signaling the pituitary gland to secrete a hormone called adrenocorticotropic hormone, or ACTH into the bloodstream. ACTH travels to the adrenal glands where it prompts the release of a hormone called cortisol from the adrenal glands.
415. Which of the following supplies the energy needed for the sodium-potassium pump to function?
- A. sodium moving down its concentration gradient
- B. breakdown of ATP
- C. changes in membrane potential
- D. osmosis of water across the cell membrane
Show Answer
Correct answer: B
The sodium-potassium pump is a large membrane-associated enzyme that uses the energy of adenosine triphosphate, or ATP, to transport sodium and potassium ions across the cell membrane.
416. Which of the following structures is NOT part of the cerebral cortex?
- A. Broca's area
- B. precentral gyrus
- C. lateral sulcus
- D. thalamus
Show Answer
Correct answer: D
The thalamus is a deep, subcortical structure located in the diencephalon that acts primarily as a relay station, routing most sensory and motor information to and from the cortex.
417. A woman awakens one morning with weakness on one side of her face. Her eyelid and corner of her mouth droop on the affected side. Her physician diagnoses Bell’s palsy. Which cranial nerve is involved?
- A. III
- B. V
- C. VII
- D. X
Show Answer
Correct answer: C
Bell’s palsy is a disorder that results from the dysfunction of cranial nerve VII, the facial nerve. The most common symptom is rapidly developing weakness on one side of the face.
418. Antipsychotic medications have traditionally reduced symptoms by blocking dopamine receptors. However, many newer atypical agents also target which other neurotransmitter receptor?
- A. GABA
- B. norepinephrine
- C. glycine
- D. serotonin
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Correct answer: D
Unlike first-generation antipsychotics that mainly block dopamine receptors, many atypical agents also target serotonin receptors. Most act as antagonists, while some newer drugs partially agonize certain serotonin receptors, allowing them to modulate rather than fully block signaling.
419. This space is located between the dura mater of the spinal cord and the bone of the vertebral column and is commonly used for the administration of analgesics and anesthetics:
- A. subarachnoid space
- B. epidural space
- C. subdural space
- D. central canal
Show Answer
Correct answer: B
The epidural space lies between the dura mater and the vertebral canal. It is a common site for epidural anesthesia and analgesia, such as during childbirth or surgery.
420. A child is born with a congenital defect that blocks the right interventricular foramen. Which ventricle or ventricles would enlarge due to cerebrospinal fluid buildup?
- A. the right lateral ventricle
- B. both lateral ventricles
- C. the third ventricle
- D. the fourth ventricle
Show Answer
Correct answer: A
Obstruction of the right interventricular foramen prevents cerebrospinal fluid from flowing from the right lateral ventricle into the third ventricle. As a result, cerebrospinal fluid accumulates proximal to the blockage, causing enlargement of the right lateral ventricle only, while the other ventricles remain normal in size.
