Final Exam

Question 1

Which of the following provided evidence of the Neuron Doctrine?

Answer 1

Staining methods (developed by Golgi!) allowed visualization of single neurons and their processes

Electron microscopy methods allowed visualization of gaps separating neurons from their targets and synaptic vesicles in axon terminals

Question 2

A cell has an internal potassium concentration of 10 mM and an external potassium concentration of 1 mM. It has an internal sodium concentration of 10 mM and an external concentration of 200 mM. The permeability of the membrane to potassium is 100, the permeability to sodium is 10. The membrane is not permeable to any other ions.

Answer 2

The resting membrane potential is closer to the sodium equilibrium potential

You have to use the GHK equation to determine this answer

Question 3

A model cell has only potassium channels in its membrane. The concentration of potassium is larger inside the cell than outside. The concentration of sodium is larger outside the cell than inside. The concentration of chloride is equal inside and outside

Answer 3

True

Question 4

The _____ and ______ are critical in determining the length constant of a neuronal membrane

Answer 4

Membrane resistance and internal resistance

Question 5

To investigate the contribution of voltage gated sodium channels to action potentials, you want to stop all of the voltage-gated potassium current associated with the action potential. Which of the below manipulation(s) on their own would be sufficient to stop the potassium current (for this question you can ignore the leak potassium channels as their contribution to action potentials is negligible)?

Answer 5

Apply TEA (a potassium channel blocker)

Question 6

Assuming an Ek = -90 mV, an initial membrane resting potential of -70mV, and an action potential threshold of -30mV, removing 50% of the potassium leak channels in the membrane would make it harder for the neuron to fire an action potential

Answer 6

False

Question 7

The larger the diameter of an axon, the _____ length constant

Answer 7

Larger

Question 8

Refer to the associated image for this question. What is the passive membrane property that accounts for why the measured voltage response at the membrane (right hand curve) DOES NOT match the Kinetics (timing) of the precise injection of electrical current (shown on the left)?

Answer 8

Capacitance

Question 9

Which of the following manipulations would INCREASE the likelihood of an action potential in our standard model cell where: Vm=-70, Ena=+58, Ek=-90, Ecl=-65?

Answer 9

Decrease Chloride conductance

Increase external potassium concentration by 10 fold

Question 10

Ensheathing the axons with Myelin in the nervous system aids the spread of both action potentials and passive electrical potentials because it raises the membrane resistance and lowers capacitance

Answer 10

True

Question 11

What is a miniature end-plate potential (mEPP)? Select all that apply

Answer 11

Spontaneous postsynaptic responses in the absence of a presynaptic action potential

Small postsynaptic responses of a unitary size, or multiples of that size

Question 12

Curare is an acetylcholine receptor antagonist. What effect does curare have on the size and frequency of mEPPs?

An acetylcholine receptor antagonist would bind to ACh receptors, preventing synaptic transmission. As such, if any mEPPs did occur in the context of curare, they would likely be _______, as some proportion of the ACh released from a single vesicle would be _______ by curare, so the mEPP response would be _______. In terms of mEPP frequency, the frequency would likely be _______, as that measure ultimately depends on the release of NT from the presynaptic terminal (which curare does not effect).

Answer 12

Smaller
Blocked
Smaller
The same

Question 13

You identify a new neurotransmitter. In order to characterize the actions of this neurotransmitter, you conduct an experiment in which you stimulate a neuron containing your NT while recording the postsynaptic current using voltage clamp (let’s you control the membrane potential, lines label the given voltages (-45 through -110).

What is the reversal potential for this receptor?

Answer 13

-90 mV

Question 14

What ion/s is/are most likely to have a high conductance through the channel described in the previous question? Remember the Eion for all the ions that affect the “model” neuron we described in module 1

Answer 14

K+, Cl-

Question 15

Decide whether the following items are associated with metabotropic (M) or ionotropic (I) receptors. Briefly describe each item.

(a) G-protein coupled receptors
(b) Rapid postsynaptic potentials
(c) An ion channel
(d) Longer-lasting postsynaptic responses

Answer 15

(a) M
(b) I
(c) I
(d) M

Question 16

NMDA receptors are often called “coincidence detectors.” What two events must coincide in order to activate these receptors?

Answer 16

Postsynaptic depolarization and glutamate binding

Question 17

_______ is a peptide neurotransmitter involved in pain transmission.

_______ is the most common excitatory transmitter in the human brain.

_______ acts on ionotropic receptors at the neuromuscular junction and both ionotropic and metabotropic receptors in the brain and affects higher functions such as learning, memory and cognition.

_______ opens a chloride channel.

Answer 17

Substance P
Glutamate
Acetylcholine
GABA

Question 18

If a synapse only contains AMPA and NMDA receptors, AMPA receptors may be activated without also activating NMDA receptors. However, it is unlikely that the NMDA receptors may be activated without also activating AMPA receptors first

Answer 18

True

Question 19

Which of the following accurately describes a known anatomical pathway in the hippocampus?

Answer 19

Entorhinal cortex to the dentate gyrus (areas) via the perforant path (axonal pathway)

CA3 to CA1 (areas) via the Schaffer collateral (axonal pathway)

Question 20

What would the fEPSP look like at 1 hour?

Answer 20

2 times as large

Question 21

What would happen to the response shown on the fEPSP plot at 5 hours if Bliss and Lomo had given a low frequency stimulation of about 1 Hz just after 4 hours?

Answer 21

The fEPSP would be smaller than the response at 4 hours

Question 22

Why is CaMKII a good candidate for a “molecular memory” molecule? Which of the following features of CaMKII explain how CAMKII can hold a ‘memory’ of synaptic activity?

Answer 22

CaMKII has the ability to phosphorylate itself (autophosphorylation) in order to turn off and on its function constitutively (until it is actively reversed)

The enzymatic activities of CaMKII is dependent on Ca2+ concentration

Question 23

LTD and LTP represent a continuum of modifications of synaptic strength. Low-frequency stimulation results in _______ of _______ receptors, which results in _______ of the receptors. This results in synaptic _______.

Answer 23

Dephosphorylation
AMPA
Endocytosis
Depression

Question 24

Hebb’s postulate from 1949 states “When an axon of cell A is near enough to excite cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.”

Which of the following are examples of how synaptic plasticity results in Growth processes?

Answer 24

Formation of new synapses

Increases in the number and size of spines

Question 25

Hebb’s postulate from 1949 states “When an axon of cell A is near enough to excite cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.”

Which of the following are examples of how synaptic plasticity results in metabolic processes?

Answer 25

Changes in postsynaptic receptor density

Increases in presynaptic neurotransmitter release

Changes in gene expression

Question 26

The term Modality when discussed in the context of sensory processing refers to

Answer 26

The physical nature of a stimulus that can be sensed and the way it is processed by the nervous system

Question 27

A Merkel cell is stimulated by a so called “Slowly Adapting type 1, low threshold mechanoreceptor” (SAI-LTMR) and has a small receptive field. Therefore, these cells in the skin of the hand are useful for sensing really hot things that cause you to reflexively withdraw your hand without needing to know exactly where the source of stimulus was

Answer 27

False

Question 28

The receptive field of a neuron is

Answer 28

The location at which a sensory stimulus must be presented in order to elicit a response from a sensory cell

Question 29

Many low-threshold mechanoreceptors ultimately send their signals to the spinal cord via the _______ myelinated A-beta axon fiber type which facilitates relatively _______ transduction of mechanosensation to the rest of the nervous system. This is in contrast to other mechanoreceptors that send their signals via the _______ myelinated A-gama fiber types with transmit electrical signals relatively _______ to the spinal cord

Answer 29

Heavily
Fast
Lightly
Slow

Question 30

The somatosensory homunculus represents the amount of “real-estate” taken in the brain to processes information from specific parts of the body. This representation of the receptive field map in the somatosensory system is useful as it makes it very apparent that we do not process information from all parts of the body with equal sensitivity

Answer 30

True

Question 31

A key component of sensory transduction in olfactory sensory neurons is that activation of a G-protein coupled receptor ultimately leads to Ca channel opening and cellular depolarization. Therefore, if an animal has a mutation in the gene that encodes for Adenyl Cyclase that renders it unresponsive to CamKII in olfactory sensory neurons, it will remain constitutively active. What might be the perceptual consequences of this altered activity of AC?

Answer 31

Sensory neurons will take longer to adapt to a constant stimulus

Perceptually, signals will last longer, making it difficult to detect different concentrations of the smell over a region of space

Question 32

In the olfactory bulb, the representation of a given odor is combinatorial such that a given odor at a given concentration will reliably activate a consistent subset of Olfactory Sensory Neuron (OSN) types. This subset of OSNs and how much they are activated is distinct from that which a different odor activates. Therefore, what would you predict for two odors that perceptually smell very similar?

Answer 32

They activate the same types of OSNs to the same degree

They both activate OSNs by binding to the same type of GPCRs

Question 33

The following receptive field properties describe which cell type found in the retina?

Center surround structure
Small dendritic arbor
Color sensitive
Inactive at night or low light levels

Answer 33

Midget cells

Question 34

Match the following properties with the type of bipolar cell that has them.

Contains inotropic glutamate receptors
Contains metabotropic glutamate receptors
Depolarized by light turning on in the center of the receptive field
Hyperpolarized by light turning on in the center of the receptive field
Signals the local INCREASE of light to the rest of the brain
Signals the local DECREASE of light to the rest of the brain

Answer 34

Off bipolar cells
On bipolar cells
On bipolar cells
Off bipolar cells
On bipolar cells
Off bipolar cells

Question 35

The center surround structure of the receptive field of a color responsive ganglion cell type (think blue/yellow or red/green type) may be constructed as either the function of multiple types of bipolar cells (on center and off center) receiving and integrating information from neighboring photoreceptor cells and/or lateral inhibition processes mediated via horizontal and amacrine cells. Which of the following is a perceptual/functional consequence of these circuit interactions?

Answer 35

Conscious color perception is highly subject to local contrast

The perception of one color for a prolonged period of time (adaptation) causes perception of its complimentary color when you take away the first color

Small regions of space where complimentary colors are juxtaposed form sharper borders visually (may be detected with finer resolution) than non complimentary colors

Question 36

Transduction of sound waves into electrical activity in hair cells is unique relative to signal transduction in photoreceptor neurons and olfactory sensory neurons because mechanical motion of the cells is directly translated into the opening of cation channels which rapidly lets in K+ leading to the opening of voltage gated Ca2+ channels and the rapid release of glutamate

Answer 36

True

Question 37

Humans use a combination of Binaural (needs two ears) and Monaural cues (only needs to be detected in one ear) to spatially localize the source of a sound. Which of the following aids humans and other mammals to localize the source of a sound?

Answer 37

ITD and ILD

Changing the position of your ears along the vertical axis

Question 38

Which of the following applies to a description of the parasympathetic nervous system?

Answer 38

Facilitates feeding and mating behaviors

Question 39

Which of the following is NOT directly regulated by hypothalamic activity?

Answer 39

None of the above

Mating, sleep, hunger

Question 40

Fruitless is a gene that regulates whether or not a fly turns out homosexual

Answer 40

False

Question 41

If a male child endures a botched circumcision and the doctor turns him into a female by removing his testes and creating a vagina, that individual will never know the difference because sex hormones only influence behaviors and the brain after puberty

Answer 41

False

Question 42

Aromatase is an enzyme that does which of the following?

Answer 42

Converts testosterone to estrogen

Question 43

Select all that characterize a homeostatic process

Answer 43

Maintains relative stability of physiological state

Requires a sensor to determine when the system deviates from an optimal set point

Responsive to system feedback

Question 44

Activation of either POMC or AgRP neurons causes mice to feed more

Answer 44

False

Question 45

Which of the following signals comes from the stomach to activate hypothalamic neurons to increase feeding behaviors?

Answer 45

Ghrelin

Question 46

Which of the following are key components of biological clocks?

Answer 46

Input-Zeitgeber, pacemaker, output

Question 47

Where are the neural circuits located that primarily regulate the pace of circadian rhythms?

Answer 47

SCN

Question 48

Which of the following is true about the process of sensitization?

Answer 48

It differs from habituation in that it is an INCREASE in responsiveness to the presentation of a stimulus due to a preceding intense stimulation event

Question 49

Though distinct neural circuits are implicated in the subjective, conscious experience of an emotion evoked by a stimulus VERSUS the behavioral response elicited by the same stimulus, many scientists still infer that the emotional state of an animal is reflected in its behavioral responses

Answer 49

True

Question 50

Which of the following processes involve the neural circuitry embedded within the hippocampus?

Answer 50

Being explicitly aware of newly acquired information

Spatial navigation

Keeping track of the timing between events

Question 51

SUBJECTIVE emotional EXPERIENCE is associated with the function of which of the following brain areas?

Answer 51

Medial prefrontal cortex

Question 52

For all forms of associative learning which of the following must be true?

Answer 52

The new information associated with a behavior, must PRECEDE that behavior

Learned associations are generally longer lasting than a few seconds or minutes

Question 53

Which of the following would provide evidence that animals have acquired new COGNITIVE knowledge of a relationship between a formerly novel stimulus and the reward they learn it predicts?

Answer 53

They demonstrate an understanding of a “rule” that predict reward regardless of whether the specific stimuli have been previously experienced

Question 54

Memory is just a single process described by a single molecular and cellular basis localized to hippocampal circuits

Answer 54

False