All Questions: 241-270
241. A patient presents with their right eye deviated laterally (i.e., to the side). They also are unable to move their right eye up and down. They are experiencing diplopia (double-vision) and have a slight drooping of the eyelid on the right side. Which cranial nerve has likely been affected?
- A. Optic nerve (CN II)
- B. Oculomotor nerve (CN III)
- C. Trochlear nerve (CN IV)
- D. Abducens nerve (CN VI)
Show Answer
Correct answer: B
The oculomotor nerve innervates most of the extraocular muscles (superior rectus, inferior rectus, medial rectus, inferior oblique), as well as the levator palpebrae superioris (which elevates the eyelid). CN III damage often leads to lateral deviation of the eye, impaired vertical movements, diplopia, and ptosis (drooping of the eyelid).
242. True or False: Lucid dreaming is a scientifically verified phenomenon that can occur during sleep.
- A. True
- B. False
Show Answer
Correct answer: A
Researchers have confirmed the occurrence of lucid dreaming through various methods. One approach involves instructing individuals to make specific eye movements upon entering a lucid dreaming state. Using this method, scientists have observed lucid dreamers making the specific eye movements as instructed, even though their brain activity indicated they were asleep.
243. A patient experiences a stroke affecting the posterior cerebral artery. Which of the following functions is most likely to be affected?
- A. vision
- B. fine motor control of the hand
- C. language production
- D. balance and coordination
Show Answer
Correct answer: A
The posterior cerebral artery supplies the occipital lobe, which is the primary center for visual processing. A stroke in this territory commonly causes visual deficits.
244. True or false: The main mechanism of the knee-jerk (patellar) reflex does NOT require input from the brain.
- A. True
- B. False
Show Answer
Correct answer: A
The knee-jerk reflex is a monosynaptic spinal reflex; the sensory neuron from the muscle spindle synapses directly onto the motor neuron in the spinal cord, causing contraction of the quadriceps. The brain is not required for the reflex itself, although it can modulate the strength of the response.
245. During which stage of sleep do we usually experience our most vivid dreams?
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: D
Most vivid dreaming occurs during REM (Rapid Eye Movement) sleep, a stage characterized by heightened brain activity, muscle atonia, and rapid eye movements.
246. Which of the following best describes the primary mechanism of action of cocaine in the brain?
- A. Inhibition of voltage-gated potassium channels
- B. Stimulation of serotonin synthesis
- C. Inhibition of monoamine reuptake
- D. Blockade of postsynaptic dopamine receptors
Show Answer
Correct answer: C
Cocaine binds to and inhibits the transporters responsible for the reuptake of dopamine, norepinephrine, and serotonin (monoamines) from the synaptic cleft, increasing their levels and prolonging their effects at synapses in the brain.
247. Which specialized structure, derived from ectoderm, forms during early embryonic development and eventually gives rise to the neural tube?
- A. neural crest
- B. notochord
- C. somite
- D. neural plate
Show Answer
Correct answer: D
The neural plate is a thickened region of ectoderm that appears around week 3 of development. It folds inward to form the neural groove and neural folds, which then fuse to become the neural tube---the precursor to the brain and spinal cord.
248. The term for a large, long-lasting depolarization followed by a train of action potentials that often precedes a seizure is:
- A. Afterhyperpolarization
- B. Paroxysmal depolarizing shift
- C. Temporal summation
- D. Depolarization block
Show Answer
Correct answer: B
A paroxysmal depolarizing shift is a hallmark of epileptiform activity in neurons. It’s characterized by a prolonged depolarization, often lasting hundreds of milliseconds, followed by a high-frequency burst of action potentials. This pattern can be recorded in neurons during seizure onset.
249. Which brain structure acts as a "relay station" by routing most sensory information (except smell) to the cerebral cortex?
- A. hippocampus
- B. thalamus
- C. amygdala
- D. hypothalamus
Show Answer
Correct answer: B
The thalamus is often called the brain’s "relay station" because nearly all sensory information (except olfactory signals) passes through it before reaching the cerebral cortex for processing. In fact, a great deal of all of the information traveling to the cortex sis first sent to the thalamus. It plays a crucial role in filtering and directing information to the appropriate cortical areas.
250. Which of the following brain structures is most closely associated with the abnormal brain activity seen in obsessive-compulsive disorder (OCD)?
- A. visual cortex
- B. medulla
- C. basal ganglia
- D. hypothalamus
Show Answer
Correct answer: C
The basal ganglia are involved in habit formation and the regulation of motor and cognitive routines. In OCD, abnormal activity in the basal ganglia is thought to contribute to the intrusive thoughts and repetitive behaviors that characterize the disorder.
251. This neural tube structure eventually forms the thalamus, hypothalamus, epithalamus, and subthalamus:
- A. telencephalon
- B. metencephalon
- C. mesencephalon
- D. diencephalon
Show Answer
Correct answer: D
The diencephalon is the neural tube structure that gives rise to the thalamus, hypothalamus, and several other subcortical structures. It develops from the prosencephalon.
252. Which of the following cell types provides direct input to bipolar cells in the retina?
- A. ganglion cells
- B. optic nerve fibers
- C. radial glia
- D. photoreceptors
Show Answer
Correct answer: D
Photoreceptors (rods and cones) synapse directly onto bipolar cells, initiating the flow of visual information that will eventually reach the brain and form a visual scene.
253. Which type of neuron is primarily found in the anterior horn of the spinal cord?
- A. sensory neurons
- B. interneurons
- C. autonomic neurons
- D. motor neurons
Show Answer
Correct answer: D
The anterior horn of the spinal cord primarily contains motor neurons. These are the lower motor neurons that send axons out through the ventral roots to innervate skeletal muscles. While some interneurons are present in this region, the anterior horn is defined by its population of large motor neuron cell bodies.
254. The cerebral cortex is primarily made up of:
- A. gray matter
- B. white matter
Show Answer
Correct answer: A
The cerebral cortex is the outermost layer of the brain. It is made up primarily of gray matter that is extensively folded, forming ridges called gyri and grooves called sulci.
255. Which of the following drugs is a dopamine precursor commonly used in the treatment of Parkinson’s disease?
- A. norepinephrine
- B. domperidone
- C. levodopa
- D. carbidopa
Show Answer
Correct answer: C
Levodopa (L-DOPA) is a precursor to dopamine that crosses the blood-brain barrier and is converted into dopamine in the brain. It is the most common treatment for Parkinson's disease.
256. Which of the following types of substances would be most likely to cross the blood-brain barrier (BBB)?
- A. Large, hydrophilic molecules
- B. Small, lipophilic molecules
- C. Charged ions
- D. medium-sized, hydrophilic molecules
Show Answer
Correct answer: B
The blood-brain barrier is a complex that surrounds most of the blood vessels in the brain. It acts as a barrier between the bloodstream and the extracellular space of the brain, allowing only certain substances like water, oxygen, and small lipid-soluble substances to easily cross from the blood into the brain.
257. Methadone is often used to treat opioid addiction. Its action at the opioid receptor is as a/an:
- A. antagonist (blocks receptor activity)
- B. full agonist (fully activates the receptor)
- C. partial agonist (activates the receptor but with less effect than full agonist)
- D. inverse agonist (produces opposite effect of receptor activation)
Show Answer
Correct answer: B
Methadone is a full agonist at μ-opioid receptors (similar to other opioids). Taken orally, it has a slow onset and long half-life, providing steady effects that reduce withdrawal and cravings while also avoiding injection-related risks like blood-borne infections.
258. The use of lobotomy as a psychiatric treatment in the mid-20th century declined rapidly after the development of which drug?
- A. lithium
- B. fluoxetine
- C. alprazolam
- D. chlorpromazine
Show Answer
Correct answer: D
Chlorpromazine, introduced in the 1950s, was the first effective antipsychotic medication. Its ability to manage symptoms of schizophrenia and other psychiatric disorders provided a safer and more effective alternative to lobotomy, leading to a dramatic decline in the use of the surgical technique.
259. This sulcus separates the temporal lobe from the frontal and parietal lobes:
- A. central sulcus
- B. calcarine sulcus
- C. lateral sulcus (Sylvian fissure)
- D. longitudinal fissure
Show Answer
Correct answer: C
The lateral sulcus (Sylvian fissure) is the boundary between the temporal lobe (below) and the frontal and parietal lobes (above). The central sulcus separates the frontal from the parietal lobe, the calcarine sulcus is within the occipital lobe, and the longitudinal fissure divides the two cerebral hemispheres.
260. Most of the cerebral cortex in humans is considered:
- A. neocortex
- B. allocortex
- C. mesocortex
- D. paleocortex
Show Answer
Correct answer: A
Most of the cerebral cortex in humans is classified as neocortex, which is so named because it is thought to have appeared relatively recently in vertebrate evolution. The rest of the cerebral cortex is made up of either allocortex or mesocortex, which is a transition area between the neocortex and allocortex.
261. What makes the nodes of Ranvier important to the propagation of action potentials?
- A. They store and release neurotransmitters
- B. They prevent the action potential from traveling backward along the axon
- C. They insulate the axon to increase conduction velocity
- D. They are densely populated with voltage-gated sodium channels
Show Answer
Correct answer: D
Nodes of Ranvier contain high concentrations of voltage-gated sodium channels, which allow action potentials to be regenerated at each node. This enables saltatory conduction, where the signal “jumps” from node to node, greatly increasing conduction speed along myelinated axons.
262. What is the most common cause of spontaneous subarachnoid hemorrhage?
- A. ischemic stroke
- B. rupture of a brain aneurysm
- C. meningitis
- D. seizure
Show Answer
Correct answer: B
The most common cause of spontaneous (non-traumatic) subarachnoid hemorrhage is the rupture of a brain aneurysm.
263. Fatal insomnia is a prion disease marked by progressively worsening sleep disturbances. It involves neurodegeneration that is most pronounced in which of the brain regions below?
- A. hippocampus
- B. cerebellum
- C. thalamus
- D. amygdala
Show Answer
Correct answer: C
In fatal insomnia, damage to the sleep-promoting regions of the thalamus is thought to be especially important to causing the insomnia that occurs in the disease.
264. Which thin, web-like extensions of the arachnoid mater span the subarachnoid space and connect the arachnoid mater to the pia mater?
- A. denticulate ligaments
- B. arachnoid trabeculae
- C. choroid plexi
- D. filum terminale
Show Answer
Correct answer: B
Arachnoid trabeculae are delicate connective tissue strands that extend from the arachnoid mater to the pia mater, giving the subarachnoid space its “spider web” appearance.
265. Neurons in this brain region show especially high levels of activity when someone is looking at another person’s face, which led to the hypothesis that the region might play an important role in perceiving faces:
- A. occipital face region
- B. Wernicke's area
- C. fusiform face area
- D. precentral gyrus
Show Answer
Correct answer: C
The fusiform face area (FFA) is strongly activated when people view faces, leading researchers to propose that it is specialized for face recognition. There is some debate, however, about whether the FFA is dedicated to faces specifically or whether it plays a broader role in visual perception of things we have high familiarity or expertise with.
266. The bundle of spinal nerve roots at the lower end of the spinal cord, resembling a “horse’s tail,” is called:
- A. Filum terminale
- B. Equina medullaris
- C. Denticulate ligaments
- D. Cauda equina
Show Answer
Correct answer: D
The spinal cord is shorter than the vertebral column, which causes nerves that innervate the lower limbs to bundle together as they travel down through the vertebral column to leave at the appropriate level. The bundling nerves resemble a "horse's tail," which in Latin is cauda equina.
267. A person experiences brain trauma and is left with an inability to form new memories (anterograde amnesia). Which of the brain regions below was most likely affected to cause this deficit?
- A. nucleus accumbens
- B. cerebellum
- C. hippocampus
- D. hypothalamus
Show Answer
Correct answer: C
The hippocampus is critical for the formation of new declarative memories. Damage to the hippocampus often results in anterograde amnesia (an inability to form new memories).
268. In an industrial accident, a patient suffers a severe cervical spinal cord injury to the right side of her spinal cord, resulting in Brown-Séquard syndrome. Which of the following symptoms is most likely?
- A. loss of pain sensation on the right side of her body below the damage
- B. loss of touch and proprioception on the left side of her body below the damage
- C. paralysis on the left side of the body below the damage
- D. paralysis on the right side of the body below the damage
Show Answer
Correct answer: D
Brown-Séquard syndrome is a rare neurological condition caused by damage to one side of the spinal cord. This type of damage results in a distinct pattern of deficits due to the way different nerve tracts travel through the spinal cord. It can involve paralysis and loss of touch/proprioception on the same side as the damage, and loss of pain/temperature sensation on the opposite side from the damage.
269. Which of the following best describes glutamate?
- A. An amino acid that also functions as a neurotransmitter
- B. A monoamine neurotransmitter derived from tryptophan
- C. A catecholamine neurotransmitter derived from tyrosine
- D. An inhibitory neurotransmitter primarily found in the spinal cord and brainstem
Show Answer
Correct answer: A
Glutamate is a standard amino acid used to build proteins, and it also serves as the brain’s main excitatory neurotransmitter.
270. Which of the following best describes the meaning of the term long-term depression (LTD) in neuroscience?
- A. A long-lasting decrease in serotonin levels
- B. A long-lasting decrease in synaptic strength
- C. The inability of neurons to fire action potentials after prolonged stimulation
- D. A progressive loss of neurons in the hippocampus with aging
Show Answer
Correct answer: B
LTD is a process by which synaptic connections between neurons become weaker. It is the opposing process to long-term potentiation. Although the functions of LTD are not completely understood, it’s thought to be important to memory formation, perhaps by resetting previous synaptic changes to allow for new memories to be formed via long-term potentiation.
