From class of 2010 – Neurophysiology Block 4
Select the correct answer to the following 40 questions.
1. A 54-year-old man is evaluated by a neurologist because of a gait disorder. When the physician
passively moves the patient’s right great toe upward and downward, the patient cannot
accurately report the direction of motion, although his perception of light touch and painful
stimuli is unimpaired. This finding can be best explained by a lesion of which of the following
A. Right fasciculus cuneatus
B. Left fasciculus cuneatus
C. Right fasciculus gracilis
D. Left second order neuron of the anterolateral pathway
2. Synaptic transmission involving G-protein-coupled receptors, as compared with transmission
involving ligand-gated ion channels, is:
A. slower and involves more local postsynaptic changes
B. slower and involves more widespread postsynaptic changes, including secondary
C. faster and involves more local postsynaptic changes
D. faster and involves more widespread postsynaptic changes
3. A neuron in the motor cortex sends branches of its axon to the spinal cord, the pontine nucleus
and the red nucleus. This is an example of
C. Positive feedback
D. Monosynaptic reflex
4. Short term habituation is characterized by all of the following EXCEPT
A. It is a direct result of reduced activity in sensory neurons and their central connections
B. It involves reduced permeability to Ca++ at the presynaptic terminal
C. It may be caused by presynaptic inhibition
D. It depends on the enhancement of the cAMP activity postsynaptically
5. A 72-year-old patient presents complaining of shaking in his right hand and trouble starting
movements. On physical examination, he has a resting tremor of the right hand that decreases
with active movement. A ratchety pattern of resistance and relaxation is noted when his arm is
passively manipulated. The man’s face is expressionless, his voice is very soft, his posture is
slightly stooped, and he has a slow, shuffling gait. With your excellent neurophysiology background, you consider this patient being a classic presentation of Parkinson’s disease. What type of neuronal degeneration would be the most likely cause of this disease?
A. Dopaminergic neurons at substantia nigra
B. Dopaminergic neurons at the raphe nuclei
C. Serotonergic neurons at the raphe nuclei
D. Norepinephrine releasing neurons at the locus coeruleus
6. A baby is born with an unusually large head. There are no other obvious abnormalities. Ultrasound of the head demonstrates hydrocephalus with marked enlargement of the lateral ventricles. At which of the following sites is the obstruction most likely to have occurred?
A. Right Foramen of Luschka
B. Left Foramen of Luschka
C. Cerebral aqueduct (Aqueduct of Sylvius)
D. Foramen of Magendie
7. If you monocularly deprive a kitten at birth (patch up one of their eyes), there will be a shift in the mapping of ocular dominance columns in the primary visual cortex. This reorganization will be represented as _______ cells being responsive to the non-deprived (open) eye. These ocular dominance columns can be found in layers _ , __, and __ of the visual cortex.
A. Less, IV, V, VI
B. More, I, II, III
C. More, IV, V, VI
D. Less, I, II, III
8. Due to the dynamic nature of somatosensory input mapping, if you experimentally severe the median nerve of a primate animal (i.e., owl monkey) the territory in the somatosensory cortex that is deprived of input by sectioning the median nerve would undergo a "re-organization". Which of the following statements is correct considering the cortical map after the reorganization completed?
A. increased representation of the digits which were innervated by the median nerve
B. atrophy of the cortex area originally devoted to median nerve fibers
C. the cortex area which was originally devoted to median nerve fibers is taken over by
neighboring digits' nerve fibers
D. deprived somatosensory cortical area remapping allows it to function as motor cortex
9. Pertussis is a toxin that prevents the activation of G-proteins. Assuming the effector enzyme in
the postsynaptic neuron is guanylyl cyclase, what is the effect in the postsynaptic neuron when
it is stimulated in the presence of pertussis compared to normal stimulation?
A. increased levels of cyclic adenosine monophosphate in the postsynaptic neuron
B. decreased levels of cyclic adenosine monophosphate in the postsynaptic neuron
C. increased levels of cyclic guanosine monophosphate in the postsynaptic neuron
D. decreased levels of cyclic guanosine monophosphate in the postsynaptic neuron
10. NMDA receptors are coincidence detectors; that is, in order for Ca2+ to enter through NMDA
receptor channels, two conditions must be met simultaneously at the postsynaptic membrane.
These conditions are:
A. glutamate binding to the NMDA receptor and anion flux through AMPA receptor
B. glutamate binding to the NMDA receptor and depolarization of the cell membrane
C. glutamate binding to the NMDA receptor and removal of the Mg2+ block from the
D. depolarization of the cell membrane and inactivation of AMPA receptors
-------------Please use the Case below for the following two questions-----------
A 58-year-old woman, who was known to be hypertensive, was brought to the hospital one morning. She awoke paralyzed on the right side and unable to talk. Her blood pressure was 230/120. Her heartbeat was irregular, and eyegrounds showed narrowing of the arteries, hemorrhages, and exudates. She could not move her right arm and leg voluntarily. When asked to move her right arm, she picked it up with the left one. When she tried to smile, the facial muscles on the left side of her face contracted, but those on the right side did not. However, she could furrow her brow bilaterally and close both eyes tightly. The phasic stretch reflexes were increased in the right extremities, and the sign of Babinski was present on the right side. Sensory tests were difficult to perform because of the speech problem.
11. What kind of speech problem did she have?
A. Receptive aphasia (Wernicke's aphasia)
B. Expressive aphasia (Broca's aphasia)
12. What problem was responsible for her neurologic deficits?
A. hypertension related stroke
B. kidney tumor
13. A dissociative sensory loss in the arms and legs, where deficits in pain and temperature sensation appear contralateral to loss of position and vibratory senses, is a common sign of a lesion at what level?
B. internal capsule
D. spinal cord
14. When NMDA receptors are activated and LOTS of Ca2+ enters a neuron, calmodulin-dependent kinase II is activated. This activated kinase can lead to synaptic modification by which of the following mechanisms?
A. Phosphorylating AMPA receptors
B. Releasing calcium from internal stores
C. Inserting additional AMPA receptors into the postsynaptic membrane
D. All of the above
15. Which of the following statements accurately describes a difference between Long Term Potentiation (LTP) and Long Term Depression (LTD)?
A. Entry of Ca2+ into the postsynaptic cell is a trigger for LTP but not for LTD.
B. The molecular events leading to LTP include activation of a kinase, while the molecular
events leading to LTD include activation of a phosphatase.
C. The molecular events leading to both LTP and LTD include the formation of a Ca2+-
D. LTP depends on NMDA receptor activation, while LTD does not.
16. Which of the associations listed below between structures and neurotransmitters is INCORRECT?
A. locus coeruleus—norepinephrine
B. raphe nuclei—serotonin
C. substantia nigra—acetylcholine
D. ventral tegmental area—dopamine
17. You have discovered a new form of Long Term Potentiation (LTP) in the neurons lining the stomach and you believe it is dependent on activation of the second messenger cyclic guanosine monophosphate (cGMP). Which of the following experimental results supports your hypothesis?
A. drugs that inhibit protein kinase A have no effect on this LTP
B. drugs that inhibit aspartate channels abolish this LTP
C. drugs that inhibit guanylate cyclase abolish this LTP
D. drugs that inhibit glutamate channels abolish this LTP
18. All of the following are advantages of using a second messenger system except,
A. the signal is amplified
B. it is faster than using neurotransmitter-gated ion channel
C. the effects of activation are longer lasting
D. the effects of activation are more diverse (i.e. can do more than just change membrane
19. When an alpha motor neuron excites a muscle cell it does so by sending a burst of action potentials at around 50-60 Hz to cause a tetanic (smooth) contraction. This is an example of
A. temporal summation
B. spatial summation
20. Long Term Potentiation is induced experimentally by:
A. A long train of small frequency stimulation
B. A short train of high frequency stimulation
C. Applying ethanol
D. Applying NMDA receptor antagonists
21. An experiment is designed to study nerve conduction in the postsynaptic neuron. The presynaptic neuron is stimulated and electrodes are used to measure voltage changes in the postsynaptic neuron. The above graph illustrates the data collected from the postsynaptic neuron. The best explanation for this pattern is which of the following?
A. absolute refractory period
B. prolonged closing of K+ channels
C. spatial summation
D. temporal summation
22. A 22 year old female college student comes to your office complaining of problems with vision. She also brought an MRI showing a small white lesion in the periventricular area and the levels of IgG in the CSF are very high. Her muscle stretch reflexes are slightly hyperactive in the left lower limb, but normal in the right lower limb and when she walks her gait is unsteady. She states that she had similar symptoms a few months earlier, but they went away. Which of the following is the most likely diagnosis?
A. amyotrophic lateral sclerosis
B. Guillain Barre syndrome
C. multiple sclerosis
23. Brain edema is a serious complication of altered fluid dynamics (i.e., excessive water accumulation) in the brain. Continued progression of brain edema may lead to which of the following situations?
A. relaxation of the smooth muscle vasculature and decreased blood flow
B. increased blood flow, leading to increased oxygen concentration
C. vasoconstriction and decreased edema
D. compression of blood vessels, leading to ischemia and compensatory capillary dilatation
24. Under awake, resting conditions, brain metabolism accounts for about 15 per cent of the total metabolism of the body, which is among the highest metabolic rates of all tissues in the body. Which of the following cellular populations of the nervous system contributes most substantially to this high rate of metabolism?
A. ependymal cells
D. choroid plexus cells
25. Among different types of mechanoreceptors, which of the following sensory receptor considered to adapt most rapidly to a given stimulus?
A. Ruffini's corpuscle
B. Merkel's receptor
C. Pacinian corpuscle
D. Meissner's corpuscle
26. Multiple Sclerosis is a clinical condition characterized by:
A. multiple lesions of myelin coating the peripheral nerves
B. multiple lesions of the blood vessels leading to vascular sclerosis
C. sclerosis of nerve fibers in cortical gray matter
D. multiple lesions of myelin in the central nervous system
27. The amount of energy used by the brain is among the highest of any organ in the body, but unfortunately, glycogen storage in the brain is minimal. Thus, anaerobic glycolysis is not a significant source of energy. Considering this information about brain metabolism, which of the following statements is correct?
A. the brain is dependent on glucose delivery via the vascular system
B. glucose delivered to the brain via the vascular system can be stored in neurons for
C. cessation of blood flow to the brain can be safely tolerated for up to about 10 minutes
owing to brain tissue's considerable capacity for oxygen storage
D. glucose can be stored in oligodendrocytes for neurons to use
28. There are specialized regions within the CNS that lack blood brain barrier, called “leaky regions”
or circumventricular organs. These areas are directly exposed to blood solutes and macromolecules as part of neuroendocrine control system for maintaining osmolality, appropriate hormone levels, etc. Which of the following is not considered as a circumventricular
A. area postrema
B. posterior pituitary
C. subfornical organ
D. zonula occludens
-29. The enzyme carbonic anhydrase for the CO/HCO buffer system is mostly contained in which of 23
the following cells of the brain?
B. microglial cells
C. satellite cells
30. Neurons in each of the cochlear nuclei receive information from only the ear on that one side,
then these information will be communicated to which of the following nuclei with interaural delays?
A. Inferior olivary
B. Medial superior olivary
C. Nucleus ambiguus
D. Edinger-Westphal nucleus
31. A central pattern generator is
A. one of the motor loops through cerebellum or basal ganglia
B. a group of neurons firing in synchrony
C. a group of neurons which are capable of producing rhythmic movements
D. a fictitious weapon that homunculus man carries
-------------Please use the Case below for the following three questions-----------
A 23-year-old woman was brought by an ambulance to the emergency room. She had been in a fight and had been stabbed in the back at a midthoracic level with a butcher knife. A sensory examination revealed a loss of vibratory sense in the right ankle and loss of position sense in the great toe of the right foot. Pain and temperature sensation on the left side was lost below the umbilicus. She was unable to move her right lower extremity, and stretch reflexes were absent in that limb. One month later the sensory deficits were still present. At this time the reflexes in the right lower extremity were hyperactive, and an extensor plantar response (sign of Babinski) was present on the right. However, her right limb was still weak. Her condition did not change substantially at follow-up examinations over the next several years.
32. What is the segmental level of the nervous system lesion?
33. Interruption of what central nervous system pathways explains the loss of vibratory and position
sense in the right leg?
A. fasciculus cuneatus of the dorsal column-medial lemniscal pathway
B. fasciculus gracilis of the dorsal column-medial lemniscal pathway
C. anterolateral pathway
D. lateral corticospinal pathway
34. Which receptors/sense organs signal vibratory and position sense?
A. High frequency vibrations by Pacinian corpuscles; and position sense by muscle spindles
B. High frequency vibrations by Merkel's receptors; and position sense by muscle spindles
C. High frequency vibrations by Meissner's corpuscles; and, position sense by golgi tendon
D. Vibrations by free nerve endings; and, position sense by golgi tendon organs
______________________________________________________________________________ 35. It was proposed recently that Alzheimer’s disease results from impaired neuron-neuron
interactions. The proposed model is: Pre-synaptic amyloid ? Post-synaptic degradation ?
Impaired retrograde signaling ? Synaptic retraction ? Alzheimer’s disease. Given that nitric
oxide, NO, is the key molecule mediating retrograde signaling, what therapy might work to
prevent a patient with pre-synaptic amyloid from getting Alzheimer’s disease?
A. Supplying an appropriate amount of NO or NO agonist
B. Inhibiting NO
C. Giving an NMDA antagonist
D. Giving and AMPA antagonist
36. Overactivation of NMDA receptors is ischemic stroke leads to the overload of which cation
postsynaptically? +A. K 2+B. Ca C.2+ Fe+D. Mg
37. In the neocortex, layer IV (four)
A. Is largest (i.e., contains the most cells) in the primary motor cortex
B. Receives afferents from specific thalamic nuclei
C. Sends most of its efferent axons to basal ganglia, brain stem and spinal cord
D. Sends most of its efferent axons to the opposite hemisphere via the corpus callosum
-------------Please use the Case below for the following two questions-----------
A 2-month-old infant was admitted to the pediatrics ward because of failure to thrive and a large head. The infant stayed quietly in bed most of the day. The circumference of the head was 44 cm
(normal value for this age is about 40 cm). The fontanelles protruded, and the cranial sutures were separated. The skull could be transilluminated with a flashlight. Magnetic resonance imaging showed enlarged lateral, third, and fourth ventricles. The closure of the vertebrae was defective in the lower back (spina bifida). Treatment was surgical implantation of a catheter into the lateral ventricle with drainage into the peritoneum.
38. Is this a communicating or noncommunicating type of hydrocephalus?
A. communicating; because the CSF drainage is impaired within the subarachnoid space or
at the level of the arachnoid villi
B. noncommunicating; the fluid communication between the ventricular system and the
subarachnoid space is impaired
39. Which of the followings is the most probable cause of hydrocephalus in this infant?
B. malformation of the brainstem and cerebellum
C. traumatic brain injury
40. Which of the following associations related to the figure below is INCORRECT?
A. ---dorsal root ganglion
B. ---axons forming the spinothalamic tract
C. ---inhibitory interneuron
D. ---motor neuron
E. ---excitatory interneuron