Neuro Practice Questions
Compared with normals, the decrease in quantal size observed in familial infantile myasthenia would be most consistent with a. fewer calcium channels in the presynaptic terminals. b. a greater rate of spontaneous exocytosis depleting the size of the vesicle pool. c. smaller synaptic vesicles. d. a change in the sensitivity of the calcium release mechanism. e. a loss of all ACh receptors at the neuromuscular junction.
c
Listed below are the five steps in a nitric oxide (NO)-mediated signaling event. Calcium binds to calmodulin Activation of nitric oxide synthase NO diffusion for tens of micrometers Activation of guanylyl cyclase Inactivation by reaction with oxygen. Which of the following is the correct sequence of these steps? a. 1; 2; 3; 4; 5 b. 5; 4; 3; 2; 1 c. 4; 2; 3; 1; 5 d. 2; 3; 4; 1; 5 e. 1; 5; 2; 3; 4
a
After firing a short burst of action potentials in an axon, researchers observe a larger EPSP in the postsynaptic cell, and this effect seems to last a few tens of milliseconds. This is most likely due to the presynaptic terminal having a. extra calcium. b. lowered calcium. c. extra sodium. d. reduced sodium. e. extra magnesium.
a
An intermediate type of rapidly dividing neuronal precursor cell is called a a. transit amplifying cell. b. postmitotic blast cell. c. glioblast. d. neuroblast. e. SVC totipotent stem cell.
a
Cerebellar LTD depends upon a. synergistic actions of calcium and IP3 on internal calcium release channels. b. synergistic actions of sodium and IP3 on internal calcium release channels. c. activation of AMPA receptors by voltage-gated ion channels. d. binding of IP3 to clathrin to activate endocytosis. e. calcium-dependent insertion of GABA receptors into the postsynaptic membrane.
a
Extracellular matrix molecules serve as ligands for a. integrin receptors. b. unc5 and robo. c. plexin. d. cadherin. e. L1.
a
Listed below are the enzymes needed to synthesize epinephrine (adrenaline). Dopamine beta-hydroxylase Tyrosine hydroxylase Phenylethanolamine-N-methyl transferase DOPA decarboxylase. Which of the following is the correct sequence of enzyme actions in the synthesis of epinephrine? a. 2; 4; 1; 3 b. 3; 1; 4; 2 c. 2; 1; 3; 4 d. 1; 2; 4; 3 e. 2; 4; 3; 1
a
The acetylcholine receptor at the neuromuscular junction would best be described as a(n) a. channel-linked receptor. b. enzyme-linked receptor. c. G-protein-coupled receptor. d. nuclear receptor. e. gap junction.
a
The chemoattractant signaling molecule netrin a. can signal by binding to the DCC ("deleted in colorectal cancer") receptor. b. is named for nectar, because it has been equated to a nectar of the gods for its trophic effects. c. is present in very high quantities and thus attracts many axons. d. is present only in birds and mammals. e. is an integral, or fixed, component of the extracellular matrix.
a
The inventor of voltage clamp was a. Kenneth Cole. b. Alan Hodgkin. c. Andrew Huxley. d. Bernard Katz. e. Alessandro Volta.
a
The limited ability of the brain to repair itself was discovered by a. the ancient Egyptians. b. Socrates. c. Chios Hippocrates. d. Luigi Galvani. e. Santiago Ramón y Cajal.
a
The most plausible theory for the decline in plasticity that signals the end of a critical period is the a. modification of histone proteins in ways that hinder future transcription events. b. internalization of NMDA receptors. c. internalization of GABA receptors. d. unique elevations of calcium that are seen only during the critical period. e. activation of a kinase pathway that is seen only during the critical period.
a
The protein that is thought to cross-link vesicles to actin to form a reserve vesicle pool is called a. synapsin. b. synaptotagmin. c. synaptobrevin. d. synaptophysin. e. snap 25.
a
The two molecules that aid the molecular construction of most CNS synapses by recruiting pre- and post-synaptic machinery are _______ and _______. a. neurexin; neuroligin b. netrin; ephrin c. ephrin; the Eph receptor d. cadherin; protocadherin e. SynCAM; cadherin
a
Which of the following does not contribute to maintaining low levels of calcium in resting nerve cells? a. Voltage-gated calcium channels b. The plasma membrane calcium ATPase c. The smooth endoplasmic reticulum calcium ATPase d. The sodium-calcium exchanger e. Mitochondria
a
Which of the following is not integral to the functioning of protein kinases? a. Hydrolysis of GTP prior to association of the regulatory and catalytic domains b. Reliance on functionally distinct roles of the different domains c. Binding of one or more messengers to a regulatory domain d. Inhibition of a catalytic domain by a regulatory domain e. Activation of a catalytic domain via a protein conformational change
a
Which of the following is not part of the evidence for the existence of a critical period in language learning? a. Only intense language instruction can adequately compensate for early language deprivation. b. Deaf children, if unaided, are not able to develop adequate language skills. c. Deaf children receiving sign-language training are able to develop good language skills. d. By 1 year of age, toddlers lose the ability to discriminate foreign phonemes. e. By 8 years of age, the ability to acquire accent-free foreign language fluency declines.
a
Which of the following receptor types can be modulated by both barbiturates and benzodiazepines? a. GABAA b. GABAB c. GABAC d. Glycine e. Muscarinc ACh receptor
a
Which of the following statements about EPSPs in the central nervous system is false? a. They are much larger than end plate potentials. b. EPSPs occurring close together in time can summate and help bring a neuron to threshold. c. Multiple EPSPs arriving together at different locations on the dendritic tree can summate and help bring a neuron to threshold. d. Their effect in the central nervous system can be nullified by IPSPs. e. All of the above are false; none is true.
a
Which of the following statements about the LTD mechanism in cerebellar Purkinje cells is false? a. Alternating activation of climbing fibers and parallel fibers is required to induce LTD. b. The firing of parallel fibers activates mGluR receptors and generates IP3. c. Climbing fibers generate a large calcium signal in Purkinje cell dendrites. d. Both IP3 and calcium are required to activate the IP3 receptors and depress AMPA receptor activity. e. The strength of the parallel fiber synapses can be depressed for a long period of time.
a
Which of the following statements about the plasticity of synapses in the mammalian CNS is false? a. The hallmark of both short-term and long-term synaptic plasticity is that they always increase the strength of synaptic connections. b. The efficacy of synapses can be adjusted by modulating the amount of neurotransmitter that is released. c. Calcium ions play a central role in at least some forms of synaptic plasticity. d. Changes in synaptic efficacy can occur over time scales ranging from milliseconds to years. e. A variety of molecular mechanisms are involved in the different forms of synaptic plasticity.
a
Which of the following statements on either the rising or overshoot phase of the action potential is false? a. The time from threshold to maximum depolarization is essentially instantaneous (i.e., too fast to be measured accurately with current electronics). b. A positive feedback loop leads to a regenerative depolarization that would increase continuously if unchecked. c. The degree of depolarization is limited in part by the declining driving force on sodium entry. d. The degree of depolarization is limited in part by the inactivation time course for the sodium current. e. The degree of depolarization is limited in part by the activation time course of the potassium current.
a
Which of the following statements regarding the diversity of ion channels is false? a. With only six different types, potassium channels are the least diverse channel type. b. There are at least 10 different sodium channels in humans. c. Sodium channels that do not inactivate have been found. d. There are least 10 different types of calcium channels. e. Calcium channels serve diverse functions such as influencing action potential shape and mediating the release of neurotransmitters.
a
Which of the following was not observed in studies measuring the efflux of radioactive sodium from the squid giant axon? a. Dramatic increase of efflux during a brief train of action potentials b. Sharp drop in efflux when extracellular potassium was removed c. Dependence of efflux upon the presence of ATP d. Decrease of efflux when mitochondrial ATP synthesis was inhibited e. All of the above were observed.
a
Which of the following was shown to eliminate the early inward current in squid giant axons? a. Removal of external sodium b. Doubling of external sodium c. Removal of external potassium d. Doubling of external potassium e. Removal of all external cations
a
Which statement about the genesis of new neurons in the adult brain is true? a. The reports of Joseph Altman and co-workers on adult neurogenesis in rats were widely dismissed as misidentification of glia as neurons. b. Santiago Ramón y Cajal established the existence of massive neurogenesis in adult mice and rats. c. Neurons are constantly born in many parts of the CNS but then immediately undergo apoptosis. d. Adult neurogenesis could not be confirmed until neuronal birthdating techniques were developed (in the 1990s). e. Advanced techniques have made it clear that massive numbers of new neurons are born and soon integrated into the circuits of most brainstem nuclei and cortical areas.
a
The mode of action potential propagation along myelinated axons is called a. salutatory. b. scleorid. c. oligodendroid. d. ranvierian. e. hyperian.
a.
Action potentials are generated a. at most subthreshold voltages. b. only when the cell reaches threshold. c. only when the membrane potential exceeds threshold by 5 to 10 millivolts. d. intermittently, but usually when the membrane potential exceeds threshold. e. only after all of the sodium channels are open.
b
Black widow spider venom is thought to disrupt the functioning of nerve terminals by a. proteolytic cleavage of SNARE proteins. b. circumventing the calcium-regulatory step of exocytosis to promote massive exocytosis. c. binding to all molecules of synapsin, synaptotagmin, and synaptophysin and thereby preventing their normal functioning. d. punching holes in vesicles and thereby causing release of their contents into the cytosol. e. blocking calcium channels.
b
Firing an action potential in an axon initially causes a 10 mV depolarization (EPSP) in a postsynaptic neuron, but after giving a certain stimulus to the axon, firing it causes an 8 mV depolarization, after each action potential. This phenomenon is called a. enhancement. b. depression. c. facilitation. d. augmentation. e. potentiation.
b
In a signal transduction cascade using G-proteins and cAMP, which of the following is not a signal amplification step? a. Activation of G-proteins by an activated receptor b. Activation of adenylyl cyclase molecules by G-proteins c. Creation of cAMP molecules by adenylyl cyclase d. Phosphorylation of target proteins by protein kinase A e. All of the above are steps in which amplification occurs.
b
In response to the suturing of an eyelid, it was found that a. the consequences of suturing were similar in kittens and adult cats. b. suturing had dramatic effects on kittens but very little effect on cats. c. suturing resulted in a cortical lamination inversion, whereby layer 4 was moved above layers 2 and 3. d. neural cell death occurred throughout the sutured animal's visual cortex. e. neural cell death occurred specifically in the areas of the animal's cortex innervated by the sutured eye.
b
Listed below are the individual events that make up chemical synaptic transmission. Diffusion of transmitter across the synaptic cleft Depolarization of the presynaptic terminal Vesicle fusion with plasma membrane Opening of voltage-gated ion channels Activation of presynaptic, calcium-sensitive proteins. Which of the following is the correct sequence of these events? a. 1; 2; 3; 4; 5 b. 2; 4; 5; 3; 1 c. 2; 5; 4; 3; 1 d. 5; 4; 2; 3; 1 e. 1; 2; 4; 5; 3
b
Neurons exhibit a threshold above which an action potential is triggered because of a. a positive feedback loop between sodium current activation and potassium inactivation. b. a positive feedback loop between depolarization and sodium current activation. c. a negative feedback loop between sodium current activation and inactivation. d. the precise time constant of sodium channel activation (i.e., a threshold would not be observed if this were measurably changed). e. pacemaker-like activity that is present in all nerve cells.
b
Paddle-like, charged transmembrane domains of potassium channels may a. serve as a plug or inactivation gate. b. be the primary voltage sensors. c. confer ion selectivity to the channel. d. enable the aggregation of channel subunits into functional channels. e. All of the above
b
Roger Sperry's chemoaffinity hypothesis a. arises from the fact that frog axons are able to regenerate. b. is supported by the orderly reinnervation of the frog optic tectum by regenerating retinal ganglion cells. c. correctly predicted that each optic tectal neuron-retinal axon pair would have a unique molecular lock-and-key recognition signal. d. was based upon his discovery of cell adhesion molecules in the optic tectum. e. All of the above
b
Semaphorins bound to cell surfaces or the extracellular matrix a. bind to robo and slit to prevent decussation of axons. b. cause growth cones to collapse and axons to stop growing. c. produce elevated potassium levels in most growth cones. d. All of the above e. None of the above.
b
The TRP ion channel family includes channels responsive to a. complex sequences of voltage commands. b. heat and cold. c. intracellular cyclic nucleotides. d. hyperpolarization. e. ultraviolet light.
b
The capability of a nerve terminal to rapidly and dramatically produce very large changes in calcium levels is most dependent on the a. presence of calcium-selective ion channels. b. enormous gradient of calcium across the membrane. c. fact that calcium is a positively charged ion. d. fact that calcium is a divalent cation. e. All of the above are essential for producing large, rapid concentration changes.
b
The first step in developing the adult morphology of a neuron is a. insertion of voltage-gated ion channels into the cell membrane. b. establishment of an apical-basal cytoskeletal polarity. c. the appearance of an axon as the first protrusion from the cell body. d. the appearance of an apical dendrite as the first protrusion from the cell body. e. None of the above are observed during morphological development.
b
The key aspect of receptor gating in the associative induction of hippocampal LTP is that a. all glutamate receptors open automatically whenever glutamate is in the synaptic cleft. b. the NMDA receptor acts as a molecular coincidence detector. c. the AMPA receptor allows calcium into the cell only after the NMDA receptor is activated. d. both the NMDA and AMPA channels must be open in order for the cell to depolarize. e. All of the above are key aspects of LTP induction.
b
The presence of which of the following compounds or proteins in a cell makes it quite likely that the cell is a GABAergic neuron? a. Pyridoxal phosphate b. Glutamic acid decarboxylase c. GABA transaminase d. γ-hydroxybutyrate e. Glutamine
b
The proteins that establish ionic gradients are called a. passive transporters. b. active transporters. c. voltage-gated ion channels. d. ligand-gated ion channels. e. permeability transition pores.
b
The two main families of neurotransmitter receptors are _______ and _______. a. ligand-gated; ion-gated b. ionotropic; metabotropic c. voltage-gated; voltage-modulated d. cationic; anionic e. excitatory; inhibitory
b
The type of receptor that is critical for the induction of hippocampal LTP, by virtue of its admitting calcium into a dendritic spine, is called a(n) a. AMPA receptor. b. NMDA receptor. c. glycine receptor. d. cholinergic GPCR. e. noradrenergic GPCR.
b
When a muscle fiber is held at a voltage of 0 mV at the neuromuscular end plate, acetylcholine no longer produces a current because a. the acetylcholine receptor channels all close instantly at 0 mV. b. an influx of sodium is balanced by an equal efflux of potassium. c. the membrane conductance for each permeant ion is 0 at 0 mV. d. at 0 mV, the potassium ions lodge in the receptor channel and block the influx of sodium. e. the Nernst potentials for both sodium and potassium are 0 mV in muscle fibers.
b
Which of the following cell types is exquisitely sensitive to experience-driven neuronal inputs during early postnatal life? a. Cholinergic b. GABAergic c. Glycinergic d. Dopaminergic e. Serotonergic
b
Which of the following is decreased at the denervated neuromuscular junction? a. NGF b. NT3 and NT4 c. BDNF d. S laminin e. Acetylcholine receptors
b
Which of the following is not a catecholamine? a. Dopamine b. Histamine c. Norepinephrine d. Epinephrine e. All of the above are catecholamines.
b
Which of the following is not a type of damage that commonly occurs to the CNS? a. Physical trauma b. Hyperkalemia c. Hypoxia d. Neurodegeneration e. All of the above are common kinds of neural damage that occur in the CNS.
b
Which of the following is not a variant of the patch clamp technique? a. Cell attached b. Intracellular c. Whole cell d. Inside-out patch e. Outside-out patch
b
Which of the following is thought to be a major factor in the failure of damaged CNS neurons to regenerate their axons? a. There are no known adult neurons that can regenerate axons. b. Inhibitory factors prevent robust axonal regeneration in the CNS. c. Axons have no guidance regarding the direction in which they should regenerate. d. Damaged neural regions no longer express a neuroprotective caspase gene. e. Loss of glutamate from damaged regions results in too little glutamate to support synaptic signaling.
b
Which of the following kinases is activated (in part) by a lipid? a. Protein kinase A b. Protein kinase C c. Protein kinase G d. CaM kinase II e. CaM kinase IV
b
Which of the following mechanisms contributes to the long-term enhancement of the gill withdrawal reflex in Aplysia but is not involved in the short-term enhancement of the reflex? a. Activation of G-protein-coupled receptors by serotonin b. Phosphorylation of CREB c. Activation of adenylyl cyclase d. Activation of protein kinase A e. Decreased opening of potassium channels during presynaptic action potentials
b
Which of the following sensory systems has not (yet) been shown to exhibit a developmental critical period? a. Visual b. Proprioceptive c. Auditory d. Somatic sensory e. Olfactory
b
Which of the following statements about multiple sclerosis (MS) is false? a. MS is characterized by demyelination of axons along with some axon loss. b. It was recently proven that all cases of MS are due to persistent infection by a tropical parasite. c. Cases of MS vary considerably in terms of severity and progression of the illness. d. Symptoms of MS may include weakness, paralysis, double vision, monocular blindness, and abnormal somatic sensations. e. Magnetic resonance imaging can help diagnose some cases of MS.
b
Which of the following statements about myelination is false? a. Myelin sheaths are created by glial cells. b. Myelin serves to sharply increase the time constant of the axon. c. Multiple layers of closely opposed glial membranes wrap the axon and serve as an electrical insulator. d. Myelin is absent at the nodes of Ranvier. e. Sodium and potassium channels are clustered at the nodes of Ranvier.
b
Which of the following statements about neurogenesis in the forebrain of songbirds is correct? a. Each year, newborn neurons replace the entire population of all the old song-related neurons. b. Some birds may replace most of the neurons in multiple song control centers several times over a lifetime. c. New neurons are found in the forebrains of only those bird species that learn new songs each year. d. New neurons are always produced seasonally in song birds and are linked to mating rituals. e. Forebrain neurogenesis has been demonstrated to be both necessary and sufficient for the learning of new songs.
b
Which of the following statements about the critical period associated with birdsong learning is false? a. The young bird requires an older male tutor or other source of their species' song. b. Juveniles that do not learn a proper song may still be able to attract mates because of their prowess at nest building or by other displays of fitness. c. While the critical period for memorizing a song may end at about two months of age, it may be up to several years before the bird actually learns to sing the song. d. Juvenile birds are able to memorize a song after hearing it only 10 or 20 times e. A juvenile exposed only to the songs of other bird species will produce either a highly abnormal isolate song or the song of the foster species.
b
Which of the following statements about the p75 receptor is false? a. It can be activated by the same neurotrophins that activate Trk receptors. b. It is identical to the Trk receptors in terms of molecular structure and signaling pathways. c. It can initiate the c-jun transcriptional activation pathway. d. It can act through Rho GTPases to regulate neurite outgrowth. e. It is best activated by "unprocessed" neurotrophins.
b
Which of the following statements on functional reorganization after brain damage is false? a. Movements of paralyzed limbs may return to some extent. b. As recovery progresses, larger areas of cortex become activated during an experimental task (as seen by brain imaging). c. To some degree, undamaged regions of cortex can functionally substitute for damaged regions. d. The extensive connectivity of motor cortex may facilitate recovery of motor functions. e. LTP, LTD, sprouting, and changes in GABAergic circuits may all contribute to functional recovery.
b
Which of the following was an invention (by Roger Tsien) that enabled the first precise spatial and temporal measurements of intracellular calcium dynamics? a. Voltage clamp b. Fura-2 c. Calcium green d. GFP e. Channel rhodopsin
b
Which statement about competitive interactions during the innervation of the neuromuscular junction is false? a. Blocking action potentials with TTX prevents the reduction of polyneuronal innervation. b. Blocking acetylcholine receptors with curare leads to the loss of all synaptic inputs. c. Polyneuronal innervation can be visualized with stains that reveal the presynaptic terminal and postsynaptic receptors. d. Reduction of polyneuronal innervation does not result from active displacement of the "losing" input by the eventual "winner." e. The eventual mononeuronal innervation results from a "winner-take-all" process in which the losing axon's input begins to lose strength, resulting in receptor loss and then further weakening.
b
Dendritic spines a. were discovered with the invention of electron microscopy in the 1950s. b. serve as "electrical compartments" to ensure localized depolarization. c. serve as "chemical compartments" to concentrate biochemical mechanisms. d. collectively form a set of hard-wired permanent neural connections. e. are the sites of all excitatory and inhibitory synaptic transmission in the mammalian CNS.
c
Elongation of the axon proper (as it trails the growth cone) is most directly a consequence of a. actin polymerization. b. actin depolymerization. c. tubulin polymerization. d. tubulin depolymerization. e. filopodia withdrawal.
c
For which of the following reasons was the development of the voltage clamp critical to investigations of the ionic basis of the action potential? a. Voltage changes in the cell cannot be seen without voltage clamp. b. Ionic conductances can be activated only in cells that have been voltage clamped. c. Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes. d. Sodium and potassium currents are activated in non-overlapping voltage regimes. e. All of the above
c
Gap junctions (electrical synapses) a. are found only in a few species of animals. b. are far more numerous than chemical synapses. c. have larger pores than voltage-gated ion channels. d. are found only where there are large gaps between nerve cells. e. are used to pass chemical neurotransmitters.
c
If one followed a growth cone through a "decision point" at which it made a large, abrupt turn (e.g., 90 degrees), one would observe the growth cone a. forming a right-angle, with its forward neurite pointing in the direction toward which the following axon will grow. b. generating a large semi-circular lamellipodium to chemically sample the environment. c. extending numerous filopodia, as if searching for a new direction. d. bundling numerous filopodia into a battering-ram shape in order to penetrate the tissue in the new direction. e. firing barrages of action potentials to help it electrically burrow into the new tissue.
c
In terms of size, which of the following are the largest neurotransmitters? a. Biogenic amines b. Amino acid transmitters c. Neuropeptide transmitters d. Purinergic transmitters e. Gaseous transmitters
c
In the context of neuropathological activity, the phenomenon of kindling refers to a. small burns made in cortex by an electrical stimulating electrode. b. the ability to induce LTP in the amygdala and other brain regions in live animals. c. the ability of daily administration of a weak, low-amplitude train of electrical pulses to gradually evoke larger and larger behavioral responses. d. the phenomenon whereby a single, strong electrical pulse can evoke a full-blown seizure. e. chaotic patterns of neural activity resembling the flame of a candle.
c
Individual ion channels a. were visualized with the advent of the voltage clamp in 1956. b. show the same time course as macroscopic ionic currents. c. may pass thousands of ions per millisecond. d. have a different voltage dependence than the macroscopic ionic current has. e. have a different reversal potential than the macroscopic ionic current has.
c
Neurotrophic factors a. provide hundreds of directional cues to guide axons to correct target locations. b. allow the CNS to produce and maintain a large number of excess neurons. c. play a role in adjusting the size of neuronal populations to an appropriate number. d. deliver glucose to sustain cells. e. deliver ATP to sustain cells.
c
One typically finds _______ subunits in the nicotinic acetylcholine receptors. a. two b. three c. five d. seven e. nine
c
SNARE proteins participate in vesicle exocytosis by a. forming a protein coat that maintains the vesicle's integrity. b. binding calcium and then forming a pore into the vesicle. c. forming a protein complex that pulls the vesicle membrane against the plasma membrane. d. linking calcium channels to exocytotic fusion sites. e. pushing vesicles from the reserve pool into the docked pool.
c
Serotonin reuptake blockers such as fluoxetine (Prozac) are used clinically a. to treat hypertension. b. to treat panic disorders. c. as antidepressants. d. as antipsychotics. e. to treat generalized anxiety.
c
Silent synapses are "silent" because they a. have no presynaptic terminal. b. have AMPA receptors but no NMDA receptors. c. have NMDA receptors but no AMPA receptors. d. lack voltage-gated sodium channels. e. are continuously inhibited and so cannot be activated.
c
The _______ most directly affects the rate of information processing within the central nervous system. a. number of sodium channels along an axon b. number of potassium channels along an axon c. propagation speed of action potentials d. threshold voltage of neurons e. ratio of sodium to potassium channels
c
The ability of infants to _______ demonstrates an early predilection for language learning as well as the existence of a critical language-learning period. a. distinguish parental voices from the voices of non-parents b. respond to only those phonemes used in their parents' language c. distinguish phonemes used in all human languages d. exhibit "perfect pitch" e. distinguish words from nonsense syllables
c
The differential release of small, clear vesicles, versus large, dense-core vesicles, is best explained by a. biophysical differences in the vesicles' lipids that allow for easier fusion of small vesicles. b. a more sensitive calcium-release mechanism on the dense-core vesicles. c. a more delocalized calcium signal generated by intense neural stimulation. d. the presence of novel fusion proteins on the dense core vesicles that bind neuropeptides. e. All of the above
c
The most effective means to promote peripheral nerve regeneration is a. electrical stimulation of the proximal nerve trunk. b. electrical stimulation of the distal nerve trunk. c. precise reapposition of the proximal and distal nerve segments. d. injection of Schwann cells into the nearby damaged tissue. e. application of growth factors to the proximal nerve trunk.
c
The technique that provides the most direct information about the physical, three-dimensional structure of ion channels is a. the sequencing of the channel's amino acids. b. physiological measurements of ion selectivity. c. X-ray crystallography. d. fluorescence imaging of channel subunit dynamics. e. All of the above provide similar information on the channel's three-dimensional structure.
c
The transmitter GABA excites immature cortical neurons because a. immature GABA receptors pass more sodium than chloride. b. immature GABA-receptive neurons have a more negative firing threshold than mature neurons. c. immature GABA-receptive neurons express many Na+/K+/Cl- co-transporters. d. immature GABA-receptive neurons express many K+/Cl- co-transporters. e. the opening of GABA receptor channels tends to excite immature cortical networks because of the networks' wiring.
c
Which of the following correctly describes a critical period? a. Failure to respond typically results in the immediate death of the animal. b. Cortical neural networks are connected and activated for the first time. c. Latent, adaptive neural plasticity requires sensory input for its utilization. d. Sensory inputs are first connected to regions controlling motor outputs. e. Dendritic branching and synaptogenesis accelerate on a massive scale throughout the CNS.
c
Which of the following explains the unidirectional propagation of action potentials? a. The voltage dependence of the sodium channels b. The voltage dependence of the potassium channels c. The presence of a refractory period at a location where an action potential has just passed d. Sufficient "leakiness" of the axons, such that backward propagation of action potentials is prevented e. The polarized orientation of microtubules within the axon
c
Which of the following is not a feature of glutamate signaling systems? a. The presence of multiple glutamate receptor families with different ionic selectivities b. Voltage-dependent gating of certain types of glutamate receptor c. The passage of large amounts of magnesium and calcium by NMDA receptors d. The use of specialized proteins for loading glutamate into vesicles e. The use of specialized proteins for removing glutamate from the synaptic cleft
c
Which of the following is not one of the main repair processes that normally occur in mammals when nervous tissue is damaged? a. Long-range regrowth of damaged axons in the peripheral nervous system b. Restoration of damaged central neurons c. Long-range regrowth of damaged axons in the central nervous system d. Neurogenesis e. All of the above are repair processes that normally occur in mammals when nervous tissue is damaged.
c
Which of the following is not part of the hippocampus? a. Area CA1 b. Area CA3 c. Area MT d. Dentate gyrus e. None of the above; all are part of the hippocampus
c
Which of the following is the band of hippocampal dendrites that receives inputs from the Schaeffer collaterals? a. Mossy fibers b. Perforant path c. Stratum radiatum d. CA1 region e. CA3 region
c
Which of the following is the main reason that the opening of sodium channels causes a very rapid depolarization of most neurons? a. The movement of a sodium ion produces a larger voltage change than the movement of other ions. b. Sodium ion diffusion proceeds so quickly that whenever sodium channels are open, there is a rapid directional flux across the membrane. c. The conjunction of the sodium gradient and the negative membrane potential produces a very large driving force on sodium ions. d. All of the above e. None of the above
c
Which of the following ligand-gated ion channels is (are) not regulated primarily by an intracellular signal? a. The IP3 receptor located on the endoplasmic reticulum b. The potassium-activated calcium channel c. The glutamate receptor d. The cAMP- and cGMP-gated ion channels e. The acid-sensing ion channels
c
Which of the following signaling pathways does not directly involve calcium? a. Ryanodine receptor b. IP3 receptor c. cGMP d. Phospholipase C e. Calmodulin
c
Which of the following statements about LTP is false? a. LTP involves an enhancement in synaptic efficacy that can last for hours, days, weeks or even longer. b. If one synapse (A) is very strongly stimulated (sufficient to cause LTP), and another nearby synapse (B) on the same dendrite is weakly stimulated at the same time, then the second synapse (B) will also show LTP. c. If one synapse (A) is very strongly stimulated (sufficient to cause LTP), and a nearby synapse (B) on the same cell is weakly stimulated a few seconds later, then the second synapse (B) will also show LTP. d. The requirement for coincident pre- and post-synaptic activity was predicted by Donald Hebb in 1949. e. Hippocampal LTP was first reported by Bliss and Lomo about 1970.
c
Which of the following statements about protein kinase-based signaling is false? a. Serine and threonine kinases are typically activated by second messengers. b. Tyrosine kinases are typically activated by extracellular signals. c. Each protein kinase has just one specific target protein that it phosphorylates. d. The effects of protein kinases can be balanced by protein phosphatases. e. Thousands of protein kinases are expressed in the brain.
c
Which of the following statements about the spread of electrical signals/currents along an axon is false? a. The spread of a passive signal is limited by the leakage of current out of the axon. b. The time course of passive signal spread slows with increasing leakiness of the axon. c. The membrane length constant describes how far an action potential can propagate along an axon. d. Action potentials can propagate for long distances without decrement. e. Action potential propagation requires both current flow along the axon and ion fluxes across the axon membrane.
c
Which of the following types of chemical signaling acts over a small neural region encompassing a cluster of nerve cells? a. Endocrine b. Exocrine c. Paracrine d. Synaptic e. Ephaptic
c
While the nature of adenosine's actions on central circuits is not well understood, adenosine is thought to have an inhibitory or relaxing effect because of which of the following observations? a. Its presence in many inhibitory neurons b. Its ability to block the reuptake of inhibitory transmitters c. Its actions as a cofactor at glycine receptors d. The consequences of xanthine (e.g., caffeine) blockade of adenosine receptors e. The co-localization of adenosine with GABA in GABAergic synaptic vesicles
c
bWhich of the following does not stem from the application of Ohm's law to ionic conductances? a. The driving force on the ionic current is the difference between the membrane potential and the ion's Nernst potential. b. The conductance for an ion is inversely proportional to the resistance of the membrane to the passage of that ion. c. All permeant ions experience an identical driving force at each time point during the course of an action potential. d. The conductance for each ion can be calculated based on the measured ionic currents and the calculated driving force. e. The calculations stemming from Ohm's law can be used to derive a mathematical description of the action potential.
c
A key observation leading to the discovery of trophic factors was a. that neurons do not require trophic factors if they receive sufficient glucose and oxygen. b. that all neurons appeared to release a self-stimulating trophic factor. c. the chance observation of neurons with extremely fat axons growing at remarkable speeds. d. the effect of mouse tumor cells on axon growth in mice. e. a mouse tumor that rapidly killed neurons, the effect of which was blocked by an activity later identified as NGF.
d
A major implication of Hubel and Wiesel's findings of an ocular dominance critical period is that children with an eye that is visually impaired or obstructed throughout the critical period will a. become blind in just the impaired eye. b. suffer serious vision loss in both eyes. c. have a visual deficit that initially is serious but can largely be ameliorated with subsequent visual training. d. have permanently impaired depth perception and binocular fusion. e. be unable to perceive motion or color in either eye.
d
Activating end plate acetylcholine receptor channels produces 0 current at 0 mV, but is still able to elicit action potentials in muscle fibers because a. the depolarization occurs so quickly that the membrane potential goes far positive to 0 mV and produces an overshooting action potential. b. there are enough acetylcholine receptors to propagate the action potential along the length of the muscle fiber. c. the receptor is also permeable to calcium, which binds to other channels to elicit action potentials. d. depolarization of the membrane to 0 mV is sufficient to bring nearby membrane regions, which contain voltage-gated sodium channels, to threshold. e. None of the above; acetylcholine does not elicit muscle action potentials
d
After the discovery of NGF, the next discovery of a neurotrophic factor (BDNF) did not occur for a number of decades because a. it was assumed that there were no other neurotrophic factors. b. BDNF is not a protein and was undetectable in the assays being used. c. BDNF is virtually indistinguishable from NGF. d. BDNF is present in vanishingly small amounts in normal tissues. e. BDNF affects only a very small subset of neurons in cortex.
d
Axon guidance cues can affect a. actin and tubulin dynamics. b. the complement of receptors and channels at the surface of the plasma membrane. c. the expression of different neural genes. d. All of the above e. None of the above
d
Cocaine acts a. on GABAA receptors. b. as an MAO inhibitor. c. by blocking serotonin reuptake. d. by blocking dopamine reuptake. e. by blocking biogenic amine vesicular transporters.
d
Excitotoxicity a. can result from very brief (sub-millisecond) increases in glutamate levels. b. can be prevented by administration of glutamate receptor antagonists after a stroke has been diagnosed. c. has not been correlated with the potency of compounds at glutamatergic receptors. d. can occur in some forms of epilepsy and head trauma. e. has been linked to a specific intracellular signaling pathway that activates a family of excitotoxicity genes.
d
Experimentally-induced strabismus helped to confirm the role of correlation in synaptic wiring because the a. total activity in the two eyes was about the same. b. activity in the two eyes was poorly correlated because of the strabismus. c. cat animal model revealed for researchers changes in ocular dominance across area V1. d. All of the above. e. None of the above
d
Gap junctions may exhibit all of the following features except for the ability to a. pass small metabolites, including some second messengers. b. pass electrical current bidirectionally. c. pass electrical current unidirectionally. d. amplify small incoming electrical signals into large regenerative potentials. e. synchronize the activity of populations of nerve cells.
d
Henry Head, who had an idiosyncratic approach to studying peripheral nerve regeneration, is most noteworthy for his a. following regeneration for several decades. b. attaching distal nerves to central nerve tracts. c. being the first person to experimentally study nerve regeneration in monkeys. d. performing regeneration experiments on himself. e. applying nerve growth factor to the distal ends of cut nerves.
d
Hubel and Wiesel's discovery of a critical period in visual system development was based on their observations of _______ during this period. a. the number of cortical layers formed b. the diversity of neuronal cell types formed c. changes in orientation selectivity d. changes in ocular dominance e. change in the total number of cortical neurons
d
In an experiment using a series of voltage steps to study the two different ionic currents associated with the action potential (as shown in Figure 3.2), it was found that a. both currents had the exact same voltage dependence. b. both currents increased monotonically with increasingly large voltage steps. c. both currents decreased with increasingly large voltage steps. d. the early current increased initially, but then it decreased in size as the voltage step was increased. e. the late current increased initially, but then it decreased in size as the voltage step was increased.
d
In the investigation of a visual critical period, transneuronal labeling was used to a. label reciprocal circuitry (i.e., pathways from LGN to cortex and back to LGN). b. show which LGN neurons synapses onto different types of cortical neurons. c. show that the number of retinothalamic synapses from one eye equals the number of thalamocortical synapses conveying information from that same eye. d. reveal an alternating pattern of cortical innervation stemming from the left and right eye. e. All of the above
d
In which of the following ways do potassium channels in the squid giant axon differ from sodium channels? a. The potassium channels pass only a few ions per second. b. The potassium channels show little voltage dependence. c. The summing of the individual potassium channels does not reconstruct the macroscopic current. d. Once the potassium channels open in response to a voltage step command, they tend to remain open. e. All of the above
d
Learning and memory processes in the fruit fly Drosophila show striking molecular overlap with analogous processes in Aplysia, in terms of their using all of the following except a. phosphodiesterase. b. adenylyl cyclase. c. adenylyl cyclase activating pathways. d. allosteric modulation of GABA receptors. e. CREB gene regulation.
d
Listed below are the events that make up NGF-mediated growth of sensory neurons. TrkA receptor self-phosphorylation Translocation of activated kinases to the nucleus NGF-induced dimerization of membrane receptors TrkA induction of the ras signaling pathway. Which of the following is the correct sequence of events? a. 1; 4; 3; 2 b. 4; 1; 3; 2 c. 3; 4; 1; 2 d. 3; 1; 4; 2 e. 1; 3; 4; 2
d
Martha Constantine-Paton's experiments with the three-eyed frog showed that a. addition of a third eye enhanced visual acuity. b. gain-of-function experiments were no more valid than correlational experiments. c. synaptic markers were responsible for the formation of an ocular dominance pattern. d. correlated activity was responsible for the formation of an ocular dominance pattern. e. the optic tectum of frogs resembles layer 4 of mammalian visual cortex, in that both use the same molecular mechanisms to segregate binocular inputs.
d
Studies of autonomic nerve regeneration have demonstrated that a. regeneration is extremely precise: each preganglionic fiber reestablishes synapses on the exact same postganglionic cells that they previously innervated. b. only sympathetic fibers can regenerate accurately. c. only parasympathetic fibers can regenerate accurately. d. preganglionic fibers show a strong preference for innervating their normal postganglionic targets. e. autonomic regeneration occurs randomly onto both ganglion cells and target tissues.
d
The banded krait uses the neurotoxin _______ to paralyze its prey. a. nicotine b. muscarine c. conotoxin d. α-bungarotoxin e. δ-tubocurarine
d
The calcium ATPase a. is much simpler than the sodium-potassium pump because it has only three transmembrane regions. b. pumps 15 calcium ions for each molecule of ATP consumed. c. uses the same intracellular domain for both nucleotide binding and ion translocation. d. pumps calcium in a cyclical process that utilizes energy from ATP. e. is unique among transporters in that its pumping action involves no conformational changes.
d
The most important factor determining whether a receptor-operated ion channel is inhibitory or excitatory is a. the ligand-binding properties of the receptor. b. whether the permeant ion is positively or negatively charged. c. whether the permeant ion's reversal potential is positive or negative. d. whether the permeant ion's reversal potential is positive or negative to threshold. e. None of the above
d
The protein ras a. regulates cell differentiation. b. is a monomeric, or small, G-protein. c. is named after the rat sarcoma tumor virus. d. All of the above e. None of the above
d
The reported correlation between the number of dendrites and the number of innervating axons in adult rabbit ciliary ganglion cells a. was based upon a behavioral read out of ciliary ganglion function. b. served mainly to confirm similar findings established for CNS neurons. c. demonstrated that neurons cannot make more postsynaptic sites than they have dendrites. d. suggested that local competition between two nearby synapses results in the elimination of one of them. e. All of the above
d
When current is injected into an axon, a. an action potential is evoked before the current has spread any distance from the point of injection. b. the current will spread only in one direction. c. the current will spread passively only if it is a depolarizing current. d. the current will decay exponentially with increasing distance from the injection site (if no action potential is present). e. the current will propagate as an oscillating wave independently of its polarity.
d
Which of the following appears to contribute to the selectivity filter of the potassium channel? a. The channel pore narrows to fit the size of a non-hydrated potassium ion. b. Cations such as cesium are too large to pass through the pore. c. Cations such as sodium are too small to be dehydrated at the pore filter. d. All of the above e. None of the above
d
Which of the following correctly describes the connection between the atmospheric testing of nuclear weapons and cortical neurogenesis? a. Atmospheric radiation led to many mutant cortical neurons which were replaced by new ones. b. Atmospheric radionuclides produced an "isotopic haze" in cortex, against which newborn neurons were easily recognized. c. Atmospheric radionuclides suppressed cortical neurogenesis, leading to statistically smaller cortices in individuals exposed to radiation in utero. d. The lack of the 14C isotope in cortical neurons of people born before atmospheric testing (i.e., before 1955) indicates that few new neurons are incorporated into the cortex of adult humans. e. None of the above
d
Which of the following does not contribute to the laterality of retinal ganglion cell central projections? a. Expression of the Zic2 transcription factor b. Expression of EphB1 receptors in temporal retinal axons c. Expression of ephrin B2 ligand on midline glial cells d. Attraction of EphB1 axons to the ephrin B2 ligand e. All of the above contribute to the establishment of visual laterality.
d
Which of the following is a common, defining feature of membrane-bound active ion transporters? a. All transporters are electrogenic. b. All transporters transport two or more different ions. c. All catalyze the conversion of ATP to ADP. d. All are able to move at least one ion against its concentration gradient. e. All of the above
d
Which of the following is a second messenger whose activity is terminated by a phosphatase? a. Calcium b. CAMP c. cGMP d. Inositol trisphosphate e. Diacylglycerol
d
Which of the following is an "effector" of G-protein-initiated signaling mechanisms? a. Adenylyl cyclase b. Guanylyl cyclase c. Phospholipase C d. All of the above e. None of the above
d
Which of the following is an accepted criterion for defining a molecule to be a neurotransmitter? a. It must be present in the presynaptic terminal. b. It must be released in response to presynaptic electrical activity. c. It must exert an effect on the postsynaptic cell. d. All of the above e. None of the above
d
Which of the following is not a class of opioid peptides? a. Dynorphins b. Endorphins c. Enkephalins d. Endocannabinoids e. All of the above are opioid peptides.
d
Which of the following is not a form of imprinting? a. Geese following a moving object b. Rats' preference for nipple odors c. A ewe subjected to its own lamb's scent d. Maternal milk let-down in response to a baby's crying e. All of the above are examples of imprinting.
d
Which of the following is not integral to the action potential waveform? a. A change in permeability of the membrane to sodium b. A change in permeability of the membrane to potassium c. A transient increase in the sodium current d. An initial decrease in the potassium current e. A "self-activating" aspect to the rise in the sodium current
d
Which of the following is the slowest chemical signaling process? a. Ion channel-mediated depolarization b. G-protein-mediated modulation of ion channels c. Phosphorylation of effector molecules by protein kinases d. Synthesis of proteins after CREB activation e. None of the above; all have similar time courses
d
Which of the following mechanisms used in hippocampal LTD is not part of the hippocampal LTP mechanism? a. History-dependent modification of synaptic efficacy b. NMDA receptor activation c. Calcium influx d. Calcium-dependent activation of protein phosphatases e. All of the above are used in both LTD and LTP.
d
Which of the following observations would demonstrate the spike timing-dependent plasticity of synapses? a. Whether or not LTP occurs depends on the specific temporal pattern of action potentials. b. LTP occurs whenever an action potential precedes an EPSP. c. LTD occurs whenever an action potential follows an EPSP. d. Switching the relative timing of action potential and EPSP by as little as 20 ms can switch the response from LTD to LTP, or vice-versa. e. A rhythmic pattern of spike-EPSP-spike-EPSP, at 40 ms intervals, produces maximal LTP.
d
Which of the following statements about amblyopia is false? a. Critical-period related amblyopia is most often caused by strabismus. b. Congenital cataracts, if not promptly treated, can lead to permanent visual deficits. c. Nematode infections result in "river blindness" for millions of people. d. Bilateral cataracts in children produce far more serious long-term deficits than do cataracts in just one eye. e. In humans, treatment of cataracts or strabismus before the age 4 months largely prevents the damage induced by monocular visual deprivation.
d
Which of the following statements about long-term synaptic plasticity in Aplysia is false? a. The efficacy of transmission at many synapses depends upon their history of synaptic activity. b. The tracking of long-term changes in synaptic efficacy is difficult in mammalian systems because of the complexity of mammalian brains. c. The gill withdrawal reflex in Aplysia can be enhanced by pairing a noxious stimulus with a mild touch. d. Associative learning in the Aplysia gill withdrawal reflex is relatively independent of the timing or the order in which different stimuli are applied. e. Gill withdrawal behavior in Aplysia can be altered for days or weeks by means of repeated pairings of shocks and touches.
d
Which of the following statements about neurotrophin activation of tyrosine kinase (Trk) receptors is true? a. Neural growth factor activates TrkA and TrkC. b. NT-3 activates TrkC and co-activates TrkA. c. BDNF and NT-4/5 both activate TrkA. d. BDNF and NT-4/5 both activate TrkB. e. All four neurotrophins activate all three Trk receptors.
d
Which of the following statements about synapse elimination and grey matter volume is false? a. The number of cortical synapses declines during adolescence and then roughly plateaus thereafter. b. The decline in cortical synapses roughly corresponds to a generalized human "critical period." c. Synaptic decline is more prolonged in higher order (association) cortical areas than in primary sensory areas. d. Children with ADHD have slightly greater grey matter than age-matched controls at all ages. e. All of the above are false, none is true.
d
Which of the following was not seen in the voltage-clamp study of squid action potentials? a. Capacitive currents in response to hyperpolarizing voltage steps b. Capacitive currents in response to depolarizing voltage steps c. A transient inward current as a result of depolarization d. A sustained outward current as a result of hyperpolarization e. All of the above were seen in squid giant axons.
d
A significant barrier to the reconstitution of injured brain (or spinal cord) regions is a. the limited amounts of natural neurogenesis that occur in mammals. b. the inability of newborn adult neurons to form long-range connections. c. our very limited understanding of how to modify neural stem cells to produce specific populations of adult neurons. d. many unknowns concerning the complex neural architectures (numbers of cell types and connectivity) that make up the mammalian CNS. e. All of the above
e
A surprising result that emerged from the molecular analysis of ion channels was the a. size of the individual ion channels. b. voltage-dependence of the ion channels. c. time-dependence of the ion channels. d. discovery of differences in ionic selectivity. e. sheer number of different ion channels.
e
Acetylcholine is used as a neurotransmitter at a. the neuromuscular junction. b. preganglionic synapses of the autonomic (visceral motor) nervous system. c. postganglionic synapses of the sympathetic nervous system. d. widely distributed synapses in the central nervous system. e. All of the above
e
Actin and tubulin dynamics in growth cones are influenced or regulated by a. intracellular calcium. b. voltage-gated calcium channels. c. intracellular calcium stores. d. TRP channels. e. All of the above
e
Animal toxins have been discovered that a. block sodium channels. b. prolong the open state of sodium channels. c. alter the voltage-dependence of sodium channels. d. block potassium channels. e. All of the above
e
Based upon the distribution of endocannabinoid receptors in the brain, it can be surmised that these compounds have a likely influence on a. neocortex. b. the hippocampus. c. basal ganglia. d. the hypothalamus. e. All of the above
e
Critical periods are present for all of the following except a. various forms of imprinting. b. language learning in humans. c. song learning by some species of birds. d. certain kinds of visual information processing. e. All of the above are associated with critical periods.
e
Glutamate is a. the most commonly used neurotransmitter in the brain. b. neurotoxic at high concentrations. c. a nonessential amino acid. d. often synthesized from glial-synthesized glutamine. e. All of the above
e
Hebb's postulate a. implies that co-activated synaptic contacts will be strengthened and others weakened. b. is an extension of his theory of learning and memory. c. was based on the voltage-dependent properties of the NMDA receptor. d. Both a and b e. All of the above
e
In adult mammals, neural stem cells that are capable of giving rise to both neurons and glia are found in the subventricular zone of the a. cortical hemispheres. b. cerebellum. c. midbrain. d. spinal cord. e. All of the above
e
In familial hemiplegic migraine, the underlying mutation in a calcium channel causes a. abnormally functioning pain receptors in the peripheral nervous system. b. enhanced synaptic excitation of second-order pain-sensitive neurons. c. abnormal activation of thalamic pain centers. d. abnormal activation of neocortical pain centers. e. the syndrome by some unknown mechanism.
e
In the mammalian brain, a. neurogenesis occurs primarily in the thalamus and brainstem. b. newborn neurons form populations of local-circuit and long-distance projection interneurons. c. new neurons are born in the precise location where they will mature and form synaptic contacts. d. a large majority of newborn neurons will survive and integrate into existing neural circuits. e. the functional significance of adult neurogenesis, if any, is unknown.
e
In the operation of sodium-potassium ATPase, a. there is an obligatory coupling of sodium efflux and potassium influx. b. this transporter (or "pump") is electrogenic. c. phosphorylation and dephosphorylation are respectively associated with the sodium and potassium transport steps. d. the pump transports two potassium ions for every three sodium ions. e. All of the above
e
In tracking recycling of synaptic vesicles, using HRP as a vesicle marker, the observed sequence of movements of HRP was a. Endosome, coated vesicle, vesicle reserve pool b. Vesicle reserve pool, coated vesicle, endosome c. Endosome, vesicle reserve pool, coated vesicle d. Coated vesicle, vesicle reserve pool, endosome e. Coated vesicle, endosome, vesicle reserve pool
e
Miniature end-plate potentials, or MEPPs, are produced a. at miniature end-plates. b. by the smallest axons. c. in response to weak stimuli. d. by the smallest neurotransmitters. e. by spontaneous release of neurotransmitter.
e
Myasthenia gravis is characterized by a. degeneration of lower motoneurons. b. degeneration of upper motoneurons. c. mutations affecting the synthesis of acetylcholine. d. mutations affecting acetylcholine receptors. e. an autoimmune attack on acetylcholine receptors.
e
Neurotrophic factors a. ensure that the correct numbers of axons innervate each target cell. b. ensure that each axon innervates the correct number of target cells. c. are involved in the elimination of excess synaptic connections. d. influence the degree of divergence and convergence in synaptic innervation. e. All of the above
e
Peptide neurotransmitters are often released a. shortly after their synthesis in presynaptic terminals. b. as pre-propeptides. c. as propeptides. d. more readily and quickly than nonpeptide transmitters. e. together with nonpeptide transmitters.
e
The targets of the phosphatases activated during hippocampal LTD are a. voltage-gated ion channels. b. ligand-gated ion channels. c. synaptic vesicle regulatory proteins. d. postsynaptic signaling pathways. e. unknown.
e
To date, which of the following is not part of the experimental evidence favoring the vesicular release hypothesis of neurotransmission? a. Fixed size of MEPPs b. Quantized distribution of events occurring at the neuromuscular junction c. Visualization of synaptic vesicles using electron microscopy d. Correspondence between a vesicle's acetylcholine content and MEPP size e. Visualization of acetylcholine molecules diffusing out of the neck of the membrane-fused vesicle
e
Tyrosine hydroxylase is a substrate for which of the following protein kinases? a. PKA b. PKC c. CaM kinase II d. MAP kinase e. All of the above
e
Voltage clamp data, in which investigators analyzed membrane conductances during action potentials, showed all of the following except a. the sodium current was rapidly activated by depolarization. b. the potassium current activates on a comparatively slow time scale of a few ms. c. at certain potentials, there can be zero current even with a large conductance. d. depolarization leads to a time-dependent inactivation of the sodium current. e. depolarization leads to a time-dependent inactivation of the potassium current.
e
Which of the following does not play an important role in the establishment of axon tracts and in growth cone navigation? a. Cell adhesion molecules b. The establishment of cell polarity c. Cytoskeletal proteins d. Second messenger systems e. All of the above do play an important role.
e
Which of the following enhances the passage of an axonal growth cone through a glial scar in the CNS? a. Semaphorin 3A b. Ephrins c. Tenascin d. Chondroitin sulfate proteoglycan e. None of the above
e
Which of the following experiments would indicate a role for calcium in transmitter secretion? a. Observation of presynaptic depolarizing currents after blockade of sodium channels b. Voltage clamp experiments showing voltage-gated calcium channels in the presynaptic terminal c. Induction of transmitter release by injection of calcium into the presynaptic terminal d. Blockade of transmitter release by injection of calcium buffer into the presynaptic terminal e. All of the above
e
Which of the following is a major advantage to researchers of the Xenopus oocyte expression system? a. Xenopus is the only lower vertebrate whose genome has been sequenced. b. The unusually small size of the eggs makes patch-clamping relatively easy. c. The oocytes have many endogenous ion channels to which exogenous channels can be compared. d. The oocytes have quite thin membranes, which amplifies the ionic currents. e. It facilitates physiological characterization of modified ion channel genes.
e
Which of the following is a reported consequence of traumatic brain injury, such as may result from a concussion or blast injury? a. Headaches b. Depression c. Early cognitive impairment and dementia d. Appearance of tau protein deposits in the brain e. All of the above
e
Which of the following is not a feature of critical periods that support the proper development of visual systems? a. They persist over a limited window of time (relative to the animal's lifespan). b. Large circuitry effects can occur on a time scale of days. c. Sensory input is required for the adaptive process to occur. d. They result in essentially permanent changes in the affected neural circuitry. e. All of the above
e
Which of the following is not a process that would likely contribute to those changes in neural circuitry that constitute a critical period? a. Synapse elimination b. Remodeling of axonal arbors c. Neurotransmitter receptor activation d. Activation of second messenger systems e. Neurogenesis
e
Which of the following is not a type of ion transporter that has been observed? a. The sodium/calcium exchanger b. The sodium/potassium/chloride co-transporter c. The sodium/neurotransmitter co-transporter d. The sodium/proton exchanger e. All of the above transporters have been observed.
e
Which of the following is not an observation that helped to identify sodium as the early current of the action potential? a. The current declined when there was decreased driving force on sodium fluxes. b. The current disappeared near the Nernst potential for sodium. c. The early current was blocked by tetrodotoxin. d. The early current was unaffected by tetraethylammonium. e. When the late current was blocked, the reversal potential of the inward current shifted to a negative membrane potential.
e
Which of the following is not involved in the activation of CREB? a. PKA b. CaM kinase II c. MAP kinase d. ras e. All of the above contribute to CREB activation.
e
Which of the following is not part of the molecular response to peripheral nerve damage? a. Expression of N-CAM, L1, and N-cadherin in Schwann cells b. Expression of receptors complementary to cell adhesion molecules on regenerating axons c. Secretion of BDNF by Schwann cells d. Expression of Trk and P75 receptors on growth cones e. All of the above are part of the molecular response to peripheral nerve damage.
e
Which of the following statements about cell signaling pathways is true? a. Cellular responses are always short-lived. b. Cellular responses are always long-lived. c. Signaling is always initiated by membrane-bound receptors. d. Signaling is always initiated by intracellular receptors. e. None of the above is true; all are false.
e
Which of the following statements about dendritic spines is false? a. They enable localized, transient increases in calcium. b. They slow the diffusion of IP3, but do not prevent it from leaving the spine. c. They are the sites of excitatory synapses in various parts of the CNS. d. They have a bulbous head connected to a dendritic shaft by a narrow neck. e. They usually contain just three proteins: NMDA receptors, mGluR receptors, and CaM kinase II.
e
Which of the following statements about postsynaptic currents at the neuromuscular end plate is false? a. Depolarizing currents can be recorded from outside-out patches of postsynaptic membrane. b. Individual channels tend to stay open for no more than a few msec. c. Acetylcholine can induce openings of ligand-gated ion channels. d. The end plate potential is due to the opening of thousands or millions of channels. e. The end plate channels show a regenerative opening pattern that propagates an action potential along the length of the muscle fiber.
e
Which of the following statements about the adult goldfish visual system is false? a. Specific precursor cells generate all the retinal cell types except for rods. b. Rod photoreceptors are generated by a distinct precursor cell. c. As the goldfish eye grows, the retina adds a ring of new cells. d. Axons of new ganglion cells grow along the optic nerve and innervate the optic tectum. e. As new axons innervate the optic tectum, patches of neurogenesis occur throughout the tectum while maintaining the existing coordinates of the tectal visuotopic map.
e
Which of the following was not an important factor in the discoveries made from the genetic analysis of learning and memory in fruit flies? a. The ability to behaviorally assay large numbers of animals b. Development of an assay that was sensitive to learning and memory deficits c. The ability to discriminate learning deficits from sensory and motor deficits d. Development of novel apparatus to perform the behavioral assays e. All of the above were important.
e
Which of the following was not one of the features of Hodgkin and Huxley's mathematical model? a. The action potential can be reconstructed based entirely upon the time course and amplitudes of the ionic conductances. b. The fast-rising phase can be accounted for by selective sodium entry. c. The model mimics the experimentally measured refractory period. d. The falling phase can be at least partially accounted for by the activation time course of the potassium current. e. The undershoot can be accounted for by the time course of sodium current reactivation.
e
Which of the following would not be a plausible mechanism explaining synaptic depression? a. Inhibition of presynaptic calcium channels b. Activation of presynaptic potassium channels c. Depletion of docked synaptic vesicles in the presynaptic terminal d. Delayed replenishment of vesicles to the reserve pool e. Enhancement of presynaptic sodium currents
e
Which statement about the mechanisms underlying hippocampal LTP induction is false? a. An influx of calcium triggers two or more intracellular processes in the postsynaptic dendritic spine. b. Calcium may trigger the release of a retrograde messenger that enhances transmitter release from the presynaptic terminal. c. Calcium may activate CaM kinase II in such a way that it switches to a long-term "on" state. d. Calcium may activate a signaling cascade that causes the insertion of glutamate receptors into the postsynaptic membrane. e. Calcium decreases a resting leak current of sodium so that the postsynaptic cell is closer to threshold and therefore fires more easily.
e
