Which of the following statements about neural and glial cells is false?
Mitochondria are concentrated at presynaptic terminals.
The endoplasmic reticulum is concentrated in axons.
Exocytosis and endocytosis are important for synaptic communication.
Glial cells rapidly transmit long-range electrical signals.
Both b and d
Which technique first produced unequivocal support for the neuron doctrine of the nervous system (as opposed to the reticular theory)?
Golgi stain (light microscopy)
Extracellular electrical recordings
Electron microscopy of nervous tissue
Which of the following is an advantage that intracellular recordings have over extracellular recordings?
They are technically easier to obtain.
They can be used in many more parts of the nervous system.
They can record synaptic and receptor potentials.
They can record from many neurons at once.
All of the Above
Which of the following is not part of the brain?
Antibody staining is used to
identify neurons expressing specific genes.
visualize the distribution of specific proteins in the nervous system.
trace anterograde pathways.
trace retrograde pathways
reveal structural changes associated with experimental lesions
Which of the following is not an established role for glial cells?
Integrating information to assist neural computation
Maintaining the ionic milieu surrounding nerve cells
Hastening the propagation of neural impulses
Assisting synaptic transmission via neurotransmitter uptake
Providing scaffolds that assist neural development
Which of the following is a feature that distinguishes the four model organisms from other animals that have been intensively studied by neuroscientists?
Ease of genetic analysis and manipulation
Nervous systems of substantial complexity
An extensive and interesting behavioral repertoire
Specific neural structures or behaviors of interest
All of the above
Which of the following type of glial cell myelinates peripheral axons?
Representation of which of the following is best accomplished using a topographic map?
The visual world
Verbs and Nouns
Which of the following is not a true statement about a center-surround receptive field?
It can be mapped by electrophysiological recording techniques.
It is characterized by a circular center and a donut-shaped surround.
It can involve an excitatory response (e.g., to touch).
It can involve an inhibitory response (e.g., to touch).
It is found only in primary sensory cortex.
The type of nerve cell that synapses upon muscles is called a(n)
dorsal root neuron
motor neuron (or motorneuron)
Which of the following is not considered to be a “model” organism?
The nematode C. elegans
The marine snail Aplysia
The set of neurons and small ganglia associated with the digestive tract is called the _______ nervous system.
The structural brain imaging technique that relies on atoms behaving as small magnets is called
Which of the following statements about the expression of genes in the nervous system is true?
Every gene in the human genome is expressed in the CNS.
There are tens of thousands of neuron-specific genes (i.e., genes that are not expressed outside the CNS).
Most of the genes in the human genome are expressed in the CNS.
Humans have 100 times more genes than invertebrate animals such as Drosophila.
Humans have three to four times more genes than mice have.
The scientist who shared the Nobel Prize with Camillo Golgi for his anatomical studies of the CNS was
Santiago Ramon y Cajal
Cognitive neuroscience is concerned with
all of the above
The brain imaging technique that makes use of a narrow X-ray beam is called
A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons
represents convergent neural signaling.
represents divergent neural signaling.
represents massive neural integration.
must fire at very high frequencies to be useful.
can fire only at very low frequencies.
The technique that first revealed the tremendous diversity of neuronal cell types (numbering in the hundreds or thousands in vertebrate animals) is called
the Nissl stain
the Golgi stain
cresyl violet staining
Which of the following best describes nerve cells?
Nerve cells are exceptionally good conductors of electricity (much better than copper wires).
Nerve cells are similar in their electrical conduction properties to copper wires.
In comparison to copper wires, nerve cells are relatively poor conductors of electricity.
Nerve cells are unable to conduct electricity under any circumstances.
Nerve cells are electron sinks: they absorb many electrons, but no electricity comes out of them.
The resting membrane potential is not exactly equal to the Nernst potential for potassium because
the Nernst equation is not able to predict potentials that precisely.
rapid fluctuations in membrane potential prevent accurate measurements.
the membrane has some resting permeability to species other than potassium.
potassium does not contribute to the resting membrane potential.
Which of the following is not a cause of sensory receptor potentials?
he equation used to calculate membrane potential when there are multiple permeant ions is called the _______ equation.
Finch and Augustine
Which of the following statements about ionic distributions in nerve cells is false?
Potassium is higher inside cells than outside cells.
Sodium is higher outside cells than inside cells.
Chloride is higher outside cells than inside cells.
Calcium is higher outside cells than inside cells.
The total concentration of all ionic species is approximately the same for all nerve cells in all animals.
Which of the following statements about action potentials is false?
They can transmit signals over long distances.
They boost the spatial spread of electrical signals.
They are elicited by hyperpolarization.
They occur at threshold.
They are all-or-none.
A measured membrane potential of +58 mV would be consistent with _______ inside the cell and _______ outside the cell.
100 mM K+, 10 mM K+
10 mM Na+, 100 mM Na+
10 mM Cl-, 100 mM Cl-
100 mM K+, 100 mM Na+
The different electrical signals occurring in nerve cells are caused by _______ the cell membrane.
positive charges bound to the inner and outer faces of
negative charges bound to the inner and outer faces of
movements of charged proteins within the plane of
fluxes of ions across
patterns of electrical eddy currents inside
Which of the following is not necessary for neurons to communicate electrically?
Consumption of metabolic energy
Use of active transporters to create ionic gradients
Separation of large amounts of electrical charge, with excess positive charges stored inside the cell
Selective permeability of the cell membrane via different kinds of ion channels
Changes in membrane potential caused by the movement of ions across the cell membrane
Hodgkin and Katz proposed that sodium was the predominant ion associated with the firing of an action potential because
the membrane potential approaches the Na+ Nernst potential during the rising phase.
the membrane potential approaches the Na+ Nernst potential during the falling phase.
sodium ions can move more quickly than other ionic species.
sodium ions are the only ions that can flow into the nerve cell body.
the sodium gradient explains the rising phase, falling phase, and overshoot of the action potential.
Which of the following is not a reason for the usefulness of the squid giant axon in neuronal studies?
The large size of the axon makes it easy to penetrate with recording electrodes.
The axoplasm can be extruded, thus allowing studies of its composition.
Large synapses between giant nerve cells make them easy to study.
Correct Giant ion channels allow for the insertion of recording electrodes into the channels.
Properties of the squid’s axons and synapses can be related to its behavior
Studies of the ionic basis of the action potential in squid giant axon found that
decreasing sodium outside the cell decreases the size of the action potential.
decreasing sodium outside the cell increases the size of the action potential.
decreasing potassium outside the cell decreases the size of the action potential.
decreasing potassium outside the cell increases the size of the action potential.
manipulating sodium has large effects on both the size of the action potential and the resting membrane potential.
The transmembrane potential is generated by
repulsion of positive and negative charges.
diffusion of ions down a concentration gradient.
the greater mobility of small ions.
the selectivity of the membrane to pass positive charges only.
All of the above
Which of the following statements about the ionic permeability of cell membranes is false?
The permeability of some ions can be very low.
The permeability of some ions can change over time.
In resting nerve cells, the membrane is quite permeable to potassium.
In resting nerve cells, the membrane is quite permeable to sodium.
All of the above statements are true.
Which of the following factors is important in determining the membrane potential when there are multiple permeant ions?
The concentration gradient of the individual ionic species
The permeability of the membrane to the individual ionic species
The sum total of all of the ions on both sides of the membrane
Both a and b
The synaptic potential
makes communication between nerve cells possible.
occurs only in response to external stimuli.
propagates along axons.
determines the cell’s resting potential.
Which of the following is not a usual kind of potential exhibited by nerve cells?
Which of the following statements about electrochemical equilibrium is false?
Electrochemical equilibrium involves the movement of a relatively small number of ions.
Ionic gradients are necessary for the generation of the membrane potential.
The size of the potential is proportional to the size of the ion gradient.
The direction of the ion gradient determines the polarity of the membrane potential.
For a given ion concentration gradient, the resulting potential is independent of the number of charges on the ion.
Typically, neurons firing action potentials encode a signal’s intensity by
changing the size of their action potentials.
Correct changing the frequency of their action potentials.
firing at precise moments so as to signal different sized signals.
sending signals of different sizes down different axonal branches.
In their studies of the resting membrane potential of the squid giant axon, Hodgkin and Katz found that
increasing potassium outside the axon depolarized the axon’s potential.
increasing potassium outside the axon hyperpolarized the axon’s potential.
increasing sodium outside the axon depolarized the axon’s potential.
increasing sodium outside the axon hyperpolarized the axon’s potential.
changing external sodium and potassium had identical effects on the resting axon potential.
Which of the following is not an observation that helped to identify sodium as the early current of the action potential?
The current declined when there was decreased driving force on sodium fluxes.
The current disappeared near the Nernst potential for sodium.
The early current was blocked by tetrodotoxin.
The early current was unaffected by tetraethylammonium.
When the late current was blocked, the reversal potential of the inward current shifted to a negative membrane potential.
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
both currents had the exact same voltage dependence.
both currents increased monotonically with increasingly large voltage steps.
both currents decreased with increasingly large voltage steps.
the early current increased initially, but then it decreased in size as the voltage step was increased.
the late current increased initially, but then it decreased in size as the voltage step was increased.
Which of the following statements about myelination is false?
Myelin sheaths are created by glial cells.
Myelin serves to sharply increase the time constant of the axon.
Multiple layers of closely opposed glial membranes wrap the axon and serve as an electrical insulator.
Myelin is absent at the nodes of Ranvier.
Sodium and potassium channels are clustered at the nodes of Ranvier.
The mode of action potential propagation along myelinated axons is called
Which of the following was not seen in the voltage-clamp study of squid action potentials?
Capacitive currents in response to hyperpolarizing voltage steps
Capacitive currents in response to depolarizing voltage steps
A transient inward current as a result of depolarization
A sustained outward current as a result of hyperpolarization
All of the above were seen in squid giant axons.
Voltage clamp data, in which investigators analyzed membrane conductances during action potentials, showed all of the following except
the sodium current was rapidly activated by depolarization.
the potassium current activates on a comparatively slow time scale of a few ms.
at certain potentials, there can be zero current even with a large conductance.
depolarization leads to a time-dependent inactivation of the sodium current.
depolarization leads to a time-dependent inactivation of the potassium current.
For which of the following reasons was the development of the voltage clamp critical to investigations of the ionic basis of the action potential?
Voltage changes in the cell cannot be seen without voltage clamp.
Ionic conductances can be activated only in cells that have been voltage clamped.
Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes.
Sodium and potassium currents are activated in non-overlapping voltage regimes.
The inventor of voltage clamp was
Which of the following statements on either the rising or overshoot phase of the action potential is false?
The time from threshold to maximum depolarization is essentially instantaneous (i.e., too fast to be measured accurately with current electronics).
A positive feedback loop leads to a regenerative depolarization that would increase continuously if unchecked.
The degree of depolarization is limited in part by the declining driving force on sodium entry.
The degree of depolarization is limited in part by the inactivation time course for the sodium current.
The degree of depolarization is limited in part by the activation time course of the potassium current.
Neurons exhibit a threshold above which an action potential is triggered because of
a positive feedback loop between sodium current activation and potassium inactivation.
a positive feedback loop between depolarization and sodium current activation.
a negative feedback loop between sodium current activation and inactivation.
the precise time constant of sodium channel activation (i.e., a threshold would not be observed if this were measurably changed).
pacemaker-like activity that is present in all nerve cells.
Which of the following is not integral to the action potential waveform?
A change in permeability of the membrane to sodium
A change in permeability of the membrane to potassium
A transient increase in the sodium current
An initial decrease in the potassium current
A “self-activating” aspect to the rise in the sodium current
Which of the following statements about multiple sclerosis (MS) is false?
MS is characterized by demyelination of axons along with some axon loss.
It was recently proven that all cases of MS are due to persistent infection by a tropical parasite.
Cases of MS vary considerably in terms of severity and progression of the illness.
Symptoms of MS may include weakness, paralysis, double vision, monocular blindness, and abnormal somatic sensations.
Magnetic resonance imaging can help diagnose some cases of MS.
Which of the following was shown to eliminate the early inward current in squid giant axons?
Removal of external sodium
Doubling of external sodium
Removal of external potassium
Doubling of external potassium
Removal of all external cations
Action potentials are generated
at most subthreshold voltages.
only when the cell reaches threshold.
only when the membrane potential exceeds threshold by 5 to 10 millivolts.
intermittently, but usually when the membrane potential exceeds threshold.
only after all of the sodium channels are open.
The _______ most directly affects the rate of information processing within the central nervous system.
number of sodium channels along an axon
number of potassium channels along an axon
propagation speed of action potentials
threshold voltage of neurons
ratio of sodium to potassium channels
Which of the following statements about the spread of electrical signals/currents along an axon is false?
The spread of a passive signal is limited by the leakage of current out of the axon.
The time course of passive signal spread slows with increasing leakiness of the axon.
The membrane length constant describes how far an action potential can propagate along an axon.
Action potentials can propagate for long distances without decrement.
Action potential propagation requires both current flow along the axon and ion fluxes across the axon membrane.
Which of the following explains the unidirectional propagation of action potentials?
The voltage dependence of the sodium channels
The voltage dependence of the potassium channels
The presence of a refractory period at a location where an action potential has just passed
Sufficient “leakiness” of the axons, such that backward propagation of action potentials is prevented
The polarized orientation of microtubules within the axon
When current is injected into an axon,
an action potential is evoked before the current has spread any distance from the point of injection.
the current will spread only in one direction.
the current will spread passively only if it is a depolarizing current.
the current will decay exponentially with increasing distance from the injection site (if no action potential is present).
the current will propagate as an oscillating wave independently of its polarity.
Which of the following does not stem from the application of Ohm’s law to ionic conductances?
The driving force on the ionic current is the difference between the membrane potential and the ion’s Nernst potential.
The conductance for an ion is inversely proportional to the resistance of the membrane to the passage of that ion.
All permeant ions experience an identical driving force at each time point during the course of an action potential.
The conductance for each ion can be calculated based on the measured ionic currents and the calculated driving force.
The calculations stemming from Ohm’s law can be used to derive a mathematical description of the action potential.
Which of the following was not one of the features of Hodgkin and Huxley’s mathematical model?
The action potential can be reconstructed based entirely upon the time course and amplitudes of the ionic conductances.
The fast-rising phase can be accounted for by selective sodium entry.
The model mimics the experimentally measured refractory period.
The falling phase can be at least partially accounted for by the activation time course of the potassium current.
The undershoot can be accounted for by the time course of sodium current reactivation.
Which of the following is the main reason that the opening of sodium channels causes a very rapid depolarization of most neurons?
The movement of a sodium ion produces a larger voltage change than the movement of other ions.
Sodium ion diffusion proceeds so quickly that whenever sodium channels are open, there is a rapid directional flux across the membrane.
The conjunction of the sodium gradient and the negative membrane potential produces a very large driving force on sodium ions.
None of the above
In familial hemiplegic migraine, the underlying mutation in a calcium channel causes
abnormally functioning pain receptors in the peripheral nervous system.
enhanced synaptic excitation of second-order pain-sensitive neurons.
abnormal activation of thalamic pain centers.
abnormal activation of neocortical pain centers.
the syndrome by some unknown mechanism
In which of the following ways do potassium channels in the squid giant axon differ from sodium channels?
The potassium channels pass only a few ions per second.
The potassium channels show little voltage dependence.
The summing of the individual potassium channels does not reconstruct the macroscopic current.
Once the potassium channels open in response to a voltage step command, they tend to remain open.
Which of the following ligand-gated ion channels is (are) not regulated primarily by an intracellular signal?
The IP3 receptor located on the endoplasmic reticulum
The potassium-activated calcium channel
The glutamate receptor
The cAMP- and cGMP-gated ion channels
The acid-sensing ion channels
Paddle-like, charged transmembrane domains of potassium channels may
serve as a plug or inactivation gate.
be the primary voltage sensors
confer ion selectivity to the channel.
enable the aggregation of channel subunits into functional channels.
The proteins that establish ionic gradients are called
voltage-gated ion channels.
ligand-gated ion channels.
permeability transition pores.
The calcium ATPase
is much simpler than the sodium–potassium pump because it has only three transmembrane regions.
pumps 15 calcium ions for each molecule of ATP consumed.
uses the same intracellular domain for both nucleotide binding and ion translocation.
pumps calcium in a cyclical process that utilizes energy from ATP.
is unique among transporters in that its pumping action involves no conformational changes.
Which of the following is a common, defining feature of membrane-bound active ion transporters?
All transporters are electrogenic.
All transporters transport two or more different ions.
All catalyze the conversion of ATP to ADP.
All are able to move at least one ion against its concentration gradient.
In the operation of sodium–potassium ATPase,
there is an obligatory coupling of sodium efflux and potassium influx.
this transporter (or “pump”) is electrogenic.
phosphorylation and dephosphorylation are respectively associated with the sodium and potassium transport steps.
the pump transports two potassium ions for every three sodium ions.
Individual ion channels
were visualized with the advent of the voltage clamp in 1956.
show the same time course as macroscopic ionic currents.
may pass thousands of ions per millisecond.
have a different voltage dependence than the macroscopic ionic current has.
have a different reversal potential than the macroscopic ionic current has.
Which of the following was not observed in studies measuring the efflux of radioactive sodium from the squid giant axon?
Dramatic increase of efflux during a brief train of action potentials
Sharp drop in efflux when extracellular potassium was removed
Dependence of efflux upon the presence of ATP
Decrease of efflux when mitochondrial ATP synthesis was inhibited
All of the above were observed.
A surprising result that emerged from the molecular analysis of ion channels was the
size of the individual ion channels.
voltage-dependence of the ion channels.
time-dependence of the ion channels.
discovery of differences in ionic selectivity.
sheer number of different ion channels.
Which of the following appears to contribute to the selectivity filter of the potassium channel?
The channel pore narrows to fit the size of a non-hydrated potassium ion.
Cations such as cesium are too large to pass through the pore.
Cations such as sodium are too small to be dehydrated at the pore filter.
Which of the following statements regarding the diversity of ion channels is false?
With only six different types, potassium channels are the least diverse channel type.
There are at least 10 different sodium channels in humans.
Sodium channels that do not inactivate have been found.
There are least 10 different types of calcium channels.
Calcium channels serve diverse functions such as influencing action potential shape and mediating the release of neurotransmitters.
Which of the following is not a variant of the patch clamp technique?
The TRP ion channel family includes channels responsive to
complex sequences of voltage commands.
heat and cold.
intracellular cyclic nucleotides.
The technique that provides the most direct information about the physical, three-dimensional structure of ion channels is
the sequencing of the channel’s amino acids.
physiological measurements of ion selectivity.
X -ray crystallography
fluorescence imaging of channel subunit dynamics.
All of the above provide similar information on the channel’s three-dimensional structure.
Which of the following is not a type of ion transporter that has been observed?
The sodium/calcium exchanger
The sodium/potassium/chloride co-transporter
The sodium/neurotransmitter co-transporter
The sodium/proton exchanger
All of the above transporters have been observed.
Which of the following is a major advantage to researchers of the Xenopus oocyte expression system?
Xenopus is the only lower vertebrate whose genome has been sequenced.
The unusually small size of the eggs makes patch-clamping relatively easy.
The oocytes have many endogenous ion channels to which exogenous channels can be compared.
The oocytes have quite thin membranes, which amplifies the ionic currents.
It facilitates physiological characterization of modified ion channel genes.
Animal toxins have been discovered that
block sodium channels.
prolong the open state of sodium channels.
alter the voltage-dependence of sodium channels.
block potassium channels.
All of the above
The two main families of neurotransmitter receptors are _______ and _______.
Gap junctions (electrical synapses)
are found only in a few species of animals.
are far more numerous than chemical synapses.
have larger pores than voltage-gated ion channels.
are found only where there are large gaps between nerve cells.
are used to pass chemical neurotransmitters.
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
a; b; c; d; e
b; d; e; c; a
b; e; d; c; a
e; d; b; c; a
a; b; d; e; c
Black widow spider venom is thought to disrupt the functioning of nerve terminals by
proteolytic cleavage of SNARE proteins.
circumventing the calcium-regulatory step of exocytosis to promote massive exocytosis.
binding to all molecules of synapsin, synaptotagmin, and synaptophysin and thereby preventing their normal functioning.
punching holes in vesicles and thereby causing release of their contents into the cytosol.
blocking calcium channels.
Compared with normals, the decrease in quantal size observed in familial infantile myasthenia would be most consistent with
fewer calcium channels in the presynaptic terminals.
a greater rate of spontaneous exocytosis depleting the size of the vesicle pool.
smaller synaptic vesicles.
a change in the sensitivity of the calcium release mechanism.
a loss of all ACh receptors at the neuromuscular junction.
In tracking recycling of synaptic vesicles, using HRP as a vesicle marker, the observed sequence of movements of HRP was
Endosome, coated vesicle, vesicle reserve pool
Vesicle reserve pool, coated vesicle, endosome
Endosome, vesicle reserve pool, coated vesicle
Coated vesicle, vesicle reserve pool, endosome
Coated vesicle, endosome, vesicle reserve pool
Which of the following statements about postsynaptic currents at the neuromuscular end plate is false?
Depolarizing currents can be recorded from outside–out patches of postsynaptic membrane.
Individual channels tend to stay open for no more than a few msec.
Acetylcholine can induce openings of ligand-gated ion channels.
The end plate potential is due to the opening of thousands or millions of channels.
The end plate channels show a regenerative opening pattern that propagates an action potential along the length of the muscle fiber.
Miniature end-plate potentials, or MEPPs, are produced
at miniature end-plates.
by the smallest axons.
in response to weak stimuli.
by the smallest neurotransmitters.
by spontaneous release of neurotransmitter.
To date, which of the following is not part of the experimental evidence favoring the vesicular release hypothesis of neurotransmission?
Fixed size of MEPPs
Quantized distribution of events occurring at the neuromuscular junction
Visualization of synaptic vesicles using electron microscopy
Correspondence between a vesicle’s acetylcholine content and MEPP size
Visualization of acetylcholine molecules diffusing out of the neck of the membrane-fused vesicle
The most important factor determining whether a receptor-operated ion channel is inhibitory or excitatory is
the ligand-binding properties of the receptor.
whether the permeant ion is positively or negatively charged.
whether the permeant ion’s reversal potential is positive or negative.
whether the permeant ion’s reversal potential is positive or negative to threshold
Which of the following statements about EPSPs in the central nervous system is false?
They are much larger than end plate potentials.
EPSPs occurring close together in time can summate and help bring a neuron to threshold.
Multiple EPSPs arriving together at different locations on the dendritic tree can summate and help bring a neuron to threshold.
Their effect in the central nervous system can be nullified by IPSPs.
All of the above are false; none is true.
Activating end plate acetylcholine receptor channels produces 0 current at 0 mV, but is still able to elicit action potentials in muscle fibers because
the depolarization occurs so quickly that the membrane potential goes far positive to 0 mV and produces an overshooting action potential.
there are enough acetylcholine receptors to propagate the action potential along the length of the muscle fiber.
the receptor is also permeable to calcium, which binds to other channels to elicit action potentials.
depolarization of the membrane to 0 mV is sufficient to bring nearby membrane regions, which contain voltage-gated sodium channels, to threshold.
None of the above; acetylcholine does not elicit muscle action potentials
Gap junctions may exhibit all of the following features except for the ability to
pass small metabolites, including some second messengers.
pass electrical current bidirectionally.
pass electrical current unidirectionally.
amplify small incoming electrical signals into large regenerative potentials.
synchronize the activity of populations of nerve cells.
When a muscle fiber is held at a voltage of 0 mV at the neuromuscular end plate, acetylcholine no longer produces a current because
the acetylcholine receptor channels all close instantly at 0 mV.
an influx of sodium is balanced by an equal efflux of potassium.
the membrane conductance for each permeant ion is 0 at 0 mV.
at 0 mV, the potassium ions lodge in the receptor channel and block the influx of sodium.
the Nernst potentials for both sodium and potassium are 0 mV in muscle fibers.
The differential release of small, clear vesicles, versus large, dense-core vesicles, is best explained by
biophysical differences in the vesicles’ lipids that allow for easier fusion of small vesicles.
a more sensitive calcium-release mechanism on the dense-core vesicles.
a more delocalized calcium signal generated by intense neural stimulation.
the presence of novel fusion proteins on the dense core vesicles that bind neuropeptides.
SNARE proteins participate in vesicle exocytosis by
forming a protein coat that maintains the vesicle’s integrity.
binding calcium and then forming a pore into the vesicle.
forming a protein complex that pulls the vesicle membrane against the plasma membrane.
linking calcium channels to exocytotic fusion sites.
pushing vesicles from the reserve pool into the docked pool.
The protein that is thought to cross-link vesicles to actin to form a reserve vesicle pool is called
Which of the following is an accepted criterion for defining a molecule to be a neurotransmitter?
It must be present in the presynaptic terminal.
It must be released in response to presynaptic electrical activity.
It must exert an effect on the postsynaptic cell.
The capability of a nerve terminal to rapidly and dramatically produce very large changes in calcium levels is most dependent on the
presence of calcium-selective ion channels.
enormous gradient of calcium across the membrane
fact that calcium is a positively charged ion.
fact that calcium is a divalent cation.
All of the above are essential for producing large, rapid concentration changes.
Which of the following experiments would indicate a role for calcium in transmitter secretion?
Observation of presynaptic depolarizing currents after blockade of sodium channels
Voltage clamp experiments showing voltage-gated calcium channels in the presynaptic terminal
Induction of transmitter release by injection of calcium into the presynaptic terminal
Blockade of transmitter release by injection of calcium buffer into the presynaptic terminal
Acetylcholine is used as a neurotransmitter at
the neuromuscular junction.
preganglionic synapses of the autonomic (visceral motor) nervous system.
postganglionic synapses of the parasympathetic nervous system.
widely distributed synapses in the central nervous system.
can result from very brief (sub-millisecond) increases in glutamate levels.
can be prevented by administration of glutamate receptor antagonists after a stroke has been diagnosed.
has not been correlated with the potency of compounds at glutamatergic receptors.
can occur in some forms of epilepsy and head trauma.
has been linked to a specific intracellular signaling pathway that activates a family of excitotoxicity genes.
the most commonly used neurotransmitter in the brain.
neurotoxic at high concentrations.
a nonessential amino acid.
often synthesized from glial-synthesized glutamine.
Serotonin reuptake blockers such as fluoxetine (Prozac) are used clinically
to treat hypertension.
to treat panic disorders.
to treat generalized anxiety.
Peptide neurotransmitters are often released
shortly after their synthesis in presynaptic terminals.
more readily and quickly than nonpeptide transmitters.
together with nonpeptide transmitters.
The presence of which of the following compounds or proteins in a cell makes it quite likely that the cell is a GABAergic neuron?
Glutamic acid decarboxylase
One typically finds _______ subunits in the nicotinic acetylcholine receptors.
Listed below are the five steps in a nitric oxide (NO)-mediated signaling event.
1. Calcium binds to calmodulin
2. Activation of nitric oxide synthase
3. NO diffusion for tens of micrometers
4. Activation of guanylyl cyclase
5. Inactivation by reaction with oxygen
1; 2; 3; 4; 5
5; 4; 3; 2; 1
4; 2; 3; 1; 5
2; 3; 4; 1; 5
1; 5; 2; 3; 4
In terms of size, which of the following are the largest neurotransmitters?
Amino acid transmitters
Based upon the distribution of endocannabinoid receptors in the brain, it can be surmised that these compounds have a likely influence on
Which of the following is not a catecholamine?
All of the above are catecholamines.
Which of the following is not a class of opioid peptides?
All of the above are opioid peptides.
Which of the following receptor types can be modulated by both barbiturates and benzodiazepines?
Muscarinc ACh receptor
The banded krait uses the neurotoxin _______ to paralyze its prey.
on GABAA receptors.
as an MAO inhibitor.
by blocking serotonin reuptake.
by blocking dopamine reuptake.
by blocking biogenic amine vesicular transporters.
Which of the following is not a feature of glutamate signaling systems?
The presence of multiple glutamate receptor families with different ionic selectivities
Voltage-dependent gating of certain types of glutamate receptor
the passage of large amounts of magnesium and calcium by NMDA receptors
The use of specialized proteins for loading glutamate into vesicles
The use of specialized proteins for removing glutamate from the synaptic cleft
Myasthenia gravis is characterized by
degeneration of lower motoneurons.
degeneration of upper motoneurons.
mutations affecting the synthesis of acetylcholine.
mutations affecting acetylcholine receptors.
an autoimmune attack on acetylcholine receptors.
The transmitter GABA excites immature cortical neurons because
immature GABA receptors pass more sodium than chloride.
immature GABA-receptive neurons have a more negative firing threshold than mature neurons.
immature GABA-receptive neurons express many Na+/K+/Cl– co-transporters.
immature GABA-receptive neurons express many K+/Cl– co-transporters.
the opening of GABA receptor channels tends to excite immature cortical networks because of the networks’ wiring.
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?
Its presence in many inhibitory neurons
Its ability to block the reuptake of inhibitory transmitters
Its actions as a cofactor at glycine receptors
The consequences of xanthine (e.g., caffeine) blockade of adenosine receptors
The co-localization of adenosine with GABA in GABAergic synaptic vesicles
Listed below are the enzymes needed to synthesize epinephrine (adrenaline):
1. Dopamine beta-hydroxylase
2. Tyrosine hydroxylase
3. Phenylethanolamine-N-methyl transferase
4. DOPA decarboxylase
2; 4; 1; 3
3; 1; 4; 2
2; 1; 3; 4
1; 2; 4; 3
2; 4; 3; 1
Which of the following is an “effector” of G-protein-initiated signaling mechanisms?
Which of the following is not involved in the activation of CREB?
CaM kinase II
All of the above contribute to CREB activation
Which of the following is the slowest chemical signaling process?
Ion channel-mediated depolarization
G-protein-mediated modulation of ion channels
Phosphorylation of effector molecules by protein kinases
Synthesis of proteins after CREB activation
None of the above; all have similar time courses
were discovered with the invention of electron microscopy in the 1950s.
serve as “electrical compartments” to ensure localized depolarization.
serve as “chemical compartments” to concentrate biochemical mechanisms.
collectively form a set of hard-wired permanent neural connections.
are the sites of all excitatory and inhibitory synaptic transmission in the mammalian CNS.
Which of the following does not contribute to maintaining low levels of calcium in resting nerve cells?
Voltage-gated calcium channels
The plasma membrane calcium ATPase
The smooth endoplasmic reticulum calcium ATPase
The sodium–calcium exchanger
Which of the following statements about dendritic spines is false?
They enable localized, transient increases in calcium.
They slow the diffusion of IP3, but do not prevent it from leaving the spine.
They are the sites of excitatory synapses in various parts of the CNS.
They have a bulbous head connected to a dendritic shaft by a narrow neck.
They usually contain just three proteins: NMDA receptors, mGluR receptors, and CaM kinase II.
Which of the following kinases is activated (in part) by a lipid?
Protein kinase A
Protein kinase C
Protein kinase G
CaM kinase IV
Which of the following statements about cell signaling pathways is true?
Cellular responses are always short-lived.
Cellular responses are always long-lived.
Signaling is always initiated by membrane-bound receptors.
Signaling is always initiated by intracellular receptors.
None of the above is true; all are false.
Which of the following is not integral to the functioning of protein kinases?
Hydrolysis of GTP prior to association of the regulatory and catalytic domains
Reliance on functionally distinct roles of the different domains
Binding of one or more messengers to a regulatory domain
Inhibition of a catalytic domain by a regulatory domain
Activation of a catalytic domain via a protein conformational change
Listed below are the events that make up NGF-mediated growth of sensory neurons:
1. TrkA receptor self-phosphorylation
2. Translocation of activated kinases to the nucleus
3. NGF-induced dimerization of membrane receptors
4. TrkA induction of the ras signaling pathway
1; 4; 3; 2
4; 1; 3; 2
3; 4; 1; 2
3; 1; 4; 2
1; 3; 4; 2
Which of the following is a second messenger whose activity is terminated by a phosphatase?
The acetylcholine receptor at the neuromuscular junction would best be described as a(n)
Which of the following statements about protein kinase-based signaling is false?
Serine and threonine kinases are typically activated by second messengers.
Tyrosine kinases are typically activated by extracellular signals.
Each protein kinase has just one specific target protein that it phosphorylates.
The effects of protein kinases can be balanced by protein phosphatases.
Thousands of protein kinases are expressed in the brain.
Which of the following signaling pathways does not directly involve calcium?
Which of the following types of chemical signaling acts over a small neural region encompassing a cluster of nerve cells?
Which of the following was an invention (by Roger Tsien) that enabled the first precise spatial and temporal measurements of intracellular calcium dynamics?
Tyrosine hydroxylase is a substrate for which of the following protein kinases?
All of the above
Which of the following statements about the LTD mechanism in cerebellar Purkinje cells is false?
Alternating activation of climbing fibers and parallel fibers is required to induce LTD.
The firing of parallel fibers activates mGluR receptors and generates IP3.
Climbing fibers generate a large calcium signal in Purkinje cell dendrites.
Both IP3 and calcium are required to activate the IP3 receptors and depress AMPA receptor activity.
The strength of the parallel fiber synapses can be depressed for a long period of time.
The protein ras
regulates cell differentiation.
is a monomeric, or small, G-protein.
is named after the rat sarcoma tumor virus.
In a signal transduction cascade using G-proteins and cAMP, which of the following is not a signal amplification step?
Activation of G-proteins by an activated receptor
Activation of adenylyl cyclase molecules by G-proteins
Creation of cAMP molecules by adenylyl cyclase
Phosphorylation of target proteins by protein kinase A
All of the above are steps in which amplification occurs.
In the context of neuropathological activity, the phenomenon of kindling refers to
small burns made in cortex by an electrical stimulating electrode.
the ability to induce LTP in the amygdala and other brain regions in live animals.
the ability of daily administration of a weak, low-amplitude train of electrical pulses to gradually evoke larger and larger behavioral responses.
the phenomenon whereby a single, strong electrical pulse can evoke a full-blown seizure.
chaotic patterns of neural activity resembling the flame of a candle.
Which of the following was not an important factor in the discoveries made from the genetic analysis of learning and memory in fruit flies?
The ability to behaviorally assay large numbers of animals
Development of an assay that was sensitive to learning and memory deficits
The ability to discriminate learning deficits from sensory and motor deficits
Development of novel apparatus to perform the behavioral assays
All of the above were important.
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?
Activation of G-protein-coupled receptors by serotonin
Phosphorylation of CREB
Activation of adenylyl cyclase
Activation of protein kinase A
Decreased opening of potassium channels during presynaptic action potentials
Cerebellar LTD depends upon
synergistic actions of calcium and IP3 on internal calcium release channels.
synergistic actions of sodium and IP3 on internal calcium release channels.
activation of AMPA receptors by voltage-gated ion channels.
binding of IP3 to clathrin to activate endocytosis.
calcium-dependent insertion of GABA receptors into the postsynaptic membrane.
Which of the following statements about the plasticity of synapses in the mammalian CNS is false?
The hallmark of both short-term and long-term synaptic plasticity is that they always increase the strength of synaptic connections.
The efficacy of synapses can be adjusted by modulating the amount of neurotransmitter that is released.
Calcium ions play a central role in at least some forms of synaptic plasticity.
Changes in synaptic efficacy can occur over time scales ranging from milliseconds to years.
A variety of molecular mechanisms are involved in the different forms of synaptic plasticity.
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
adenylyl cyclase activating pathways.
allosteric modulation of GABA receptors.
CREB gene regulation.
Which of the following mechanisms used in hippocampal LTD is not part of the hippocampal LTP mechanism?
History-dependent modification of synaptic efficacy
NMDA receptor activation
Calcium-dependent activation of protein phosphatases
All of the above are used in both LTD and LTP.
Which of the following observations would demonstrate the spike timing-dependent plasticity of synapses?
Whether or not LTP occurs depends on the specific temporal pattern of action potentials.
LTP occurs whenever an action potential precedes an EPSP.
LTD occurs whenever an action potential follows an EPSP.
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.
A rhythmic pattern of spike–EPSP–spike–EPSP, at 40 ms intervals, produces maximal LTP.
Which of the following is not part of the hippocampus?
None of the above; all are part of the hippocampus
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
Which of the following statements about LTP is false?
LTP involves an enhancement in synaptic efficacy that can last for hours, days, weeks or even longer.
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.
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.
The requirement for coincident pre- and post-synaptic activity was predicted by Donald Hebb in 1949.
Hippocampal LTP was first reported by Bliss and Lomo about 1970.
Which statement about the mechanisms underlying hippocampal LTP induction is false?
An influx of calcium triggers two or more intracellular processes in the postsynaptic dendritic spine.
Calcium may trigger the release of a retrograde messenger that enhances transmitter release from the presynaptic terminal.
Calcium may activate CaM kinase II in such a way that it switches to a long-term “on” state.
Calcium may activate a signaling cascade that causes the insertion of glutamate receptors into the postsynaptic membrane.
Calcium decreases a resting leak current of sodium so that the postsynaptic cell is closer to threshold and therefore fires more easily.
Which of the following would not be a plausible mechanism explaining synaptic depression?
Inhibition of presynaptic calcium channels
Activation of presynaptic potassium channels
Depletion of docked synaptic vesicles in the presynaptic terminal
Delayed replenishment of vesicles to the reserve pool
Enhancement of presynaptic sodium currents
The key aspect of receptor gating in the associative induction of hippocampal LTP is that
all glutamate receptors open automatically whenever glutamate is in the synaptic cleft.
the NMDA receptor acts as a molecular coincidence detector
the AMPA receptor allows calcium into the cell only after the NMDA receptor is activated.
both the NMDA and AMPA channels must be open in order for the cell to depolarize.
All of the above are key aspects of LTP induction.
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
The targets of the phosphatases activated during hippocampal LTD are
synaptic vesicle regulatory proteins.
postsynaptic signaling pathways.
Which of the following is the band of hippocampal dendrites that receives inputs from the Schaeffer collaterals?
Which of the following statements about long-term synaptic plasticity in Aplysia is false?
The efficacy of transmission at many synapses depends upon their history of synaptic activity.
The tracking of long-term changes in synaptic efficacy is difficult in mammalian systems because of the complexity of mammalian brains.
The gill withdrawal reflex in Aplysia can be enhanced by pairing a noxious stimulus with a mild touch.
Associative learning in the Aplysia gill withdrawal reflex is relatively independent of the timing or the order in which different stimuli are applied.
Gill withdrawal behavior in Aplysia can be altered for days or weeks by means of repeated pairings of shocks and touches.
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)
Silent synapses are “silent” because they
have no presynaptic terminal.
have AMPA receptors but no NMDA receptors.
have NMDA receptors but no AMPA receptors.
lack voltage-gated sodium channels.
are continuously inhibited and so cannot be activated.