BIO467 EXAM1

Franz Nissl, a German neuropathologist, invented this immunohistochemical stain. Nissl staining primarily labels which of the following cellular structures?

Rough Endoplasmic Reticulum

Transcription

Dna to Rna

Dna

encodes genetic info

protein

performs cellular function

translation

rna to protein

mrna

signal for protein production in ribosomes

The neuron is very specialized to be able to.....

transmit electrical signals

Which of the following are ways that we can categorize neurons?

Neurochemical properties

Morphology

Connectivity

Gene Expression

Electrophysiological properties

Anatomical Location

Differential Gene Expression is critical for...

cellular diversity

maintaining cell specific functions

The technique that lets you measure the RNA from a single cell and mapping the level of expression of thousands of genes is called:

single cell RNA seq

A technique that can be used to measure the level of protein in a homogenized tissue is called..

western blotting

A lab technique that allows you to directly look at colocalization of PROTEINS in cells within an anatomical cross section of a brain

immunohistochemisty IHC

Genetic labeling allows you to target specific cell subtypes based on....

gene expression

Connexins are proteins that make _______ junctions which are pores that allow small molecules (typically ions) to pass between the cytoplasm of two cells.

Gap

Synapses in the CNS and junctions in the PNS are usually ______ synapses, meaning there's actually a small gap between the cells forming the synapse where neurotransmission occurs.

chemical

Vesicles that hold neurotransmitters are found......

in the presynaptic neuron

In the CNS each cell typically receives input via about _________ synapses.

many thousands

All neurons behave the same electrically. All action potentials fire at similar rates and the amplitude is the same across all neurons.

false

Layers across the neocortex tend to have similar cell types and contribute to the organization of information processing.

true

Cortical columns in the cortex tend to have neurons that will synapse with other neurons in the same column.

true

Which of the following forefathers of neuroscience was a major proponent of "neurone" theory

santiago ramon y cajal

Which of the following techniques would be most useful for identifying the location of a cell body that expresses mRNA for a neurotransmitter enzyme in an anatomical section of a human brain?

in situ hybridization

Which of the following techniques would be most useful for identifying the location of a synapse that contains protein for a neurotransmitter enzyme in an anatomical section of a human brain?

immunohistochemistry

Glial cells are only present in the CNS to provide structure for the brain and hold neurons together

false

Myelin is a lipid rich coating around cells that help increase the speed of electrical signals. This increased transmission speed is caused by ___________ conduction.

saltatory

Myelination

white matter

Oligodendrocytes

myelinate multiple axons

Myelinating Schwann cells

myelinate a single axon

Non-Myelenating Schwann Cells

ensheath multiple axons (remak bundle)

Astrocytes.....

can have endfeet on blood vessels

regulate ion homesostasis

can contribute to inflammatory responses

Microglia...

mediate immune response in cns

phagocytose and clear debri after injury

Cerebrospinal fluid is produced in the lateral ventricles by _______ ______.

choroid plexus

Ependymal cells have microvilli and cilia on the surface to help move ____________ around the brain.

cerebrospinal fluid

Endothelial Cells (sometimes called Pericytes) line the blood brain barrier and use ___________ junctions that physically separates blood from neurons, causing most molecules to need to be actively transported across the barrier.

tight

Multiple Sclerosis is caused by a complex immune response that crosses the blood brain barrier (BBB) and eventually causes damage to _____________, leading to aberrant neuronal communication.

myelination

Astrocyte end-feet are part of the tripartite synapse and contribute to neural circuit homeostasis by modulating...

metabolic support

ion homeostasis

blood flow

inflammatory response

synaptic transmission

A neuronal membrane that is electrically active is potentially permeable to which of the following ions?

Sodium

potassium

chloride

calcium

An electrochemical equilibrium is a balance between which of the following forces?

diffusive and electrical forces

How do ions typically cross the neuronal membrane?

Active transport by ATP hydrolyzing proteins.

ion channels

If you inserted a microelectrode into a living neuron, what is the first type of electrical potential that you would most likely observe upon entering the cell?

resting membrane potential

The concentration of potassium ions in the brain is very similar in the extracellular and intracellular space.

false

The movement of which ions contribute to Vm (membrane potential) in neurons?

sodium

potassium

chloride

calcium

Which of the following statements regarding the resting membrane potential in neurons is correct?

It is typically between 40 and 70 mV.

It is considered a positive potential.

It is linked primarily to the electrochemical equilibrium of sodium ions.

All of the above.

None of the above.

none of the above

he Nernst equation is useful for calculating EK+, ENa+, and ECl- in cells permeable to all three ions.

false

Which of the following are considered phases of an action potential?

Overshoot

Rising phase

Falling phase

Undershoot

All of the above

All of the above

Which of the following is considered a graded potential?

synaptic potential

receptor potential

What is the membrane potential (Vm) of a cell that is NOT permeable to potassium, sodium, calcium, or chloride ions?

0 mv

Suppose you have a neuron with the following starting concentrations of ions at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

What is the membrane potential of this neuron if it were only permeable to potassium?

-89 mv

-61.5 log ([Kin ]/[Kout])

Suppose you have a neuron with the following starting concentration of K+ at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

What would happen to the membrane potential of this neuron if it were only permeable to potassium and you reduced the [K+]outside.

Ek would become more negative, Vm would hyperpolarize

Suppose you have a neuron with the following starting concentrations of ions at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

[Na+]outside = 145 mM [Na+]inside = 12 mM

[Cl-]outside = 110 mM [Cl-]inside = 5 mM

67 mv

E= -61.5 log ([Na in ]/[Na out])

Suppose you have a neuron with the following starting concentrations of ions at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

[Na+]outside = 145 mM [Na+]inside = 12 mM

[Cl-]outside = 110 mM [Cl-]inside = 5 mM

What is the membrane potential at equilibrium of this neuron if the permeability to K+, Na+, and Cl- is at a ratio of 1 : 0.05 : 0.45?

-69 mv

-61.5 log {(pK[K in ] + pNa[Na in ] + pCl[Cl out ]) / (pK[K out ] + pNa[Na out ] + pCl[Cl in ])}

-61.5 log[(1140 + 0.0512 + 0.45100) / (15 + 0.05145 + 0.455)] = -69 mV

Suppose you have a neuron with the following starting concentrations of ions at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

[Na+]outside = 145 mM [Na+]inside = 12 mM

[Cl-]outside = 110 mM [Cl-]inside = 5 mM

What is the membrane potential at equilibrium of this neuron if the permeability to K+, Na+, and Cl- is at a ratio of 1 : 12 : 0.45.

Use GHK to solve the problem. The permeability of sodium has increased since resting.

-61.5 log {(pK[K in] + pNa[Na in] + pCl[Cl out]) / (pK[K out] + pNa[Na out} + pCl[Cl in])}

-61.5 log[(1140 + 0.0512 + 0.45100) / (15 + 0.05145 + 0.455)] = 44 mV

Suppose you have a neuron with the following starting concentrations of ions at 37 degrees C...

[K+]outside = 5 mM [K+]inside = 140 mM

[Na+]outside = 145 mM [Na+]inside = 12 mM

[Cl-]outside = 110 mM [Cl-]inside = 5 mM

What is the membrane potential at equilibrium of this neuron if the membrane was 100 times more permeable to potassium than sodium and impermeable to chloride?

Use GHK to solve the problem. Since the permeability are ratios, be sure that the ratio of potassium is 100 times more than sodium. Using the resting membrane permeabilities as a starting point, use PK = 5, PNa = 0.05. Since the neuron is impermeable to chloride, PCl = 0.

-61.5 log {(pK[K in] + pNa[Na in] + pCl[Cl out]) / (pK[K out] + pNa[Na out} + pCl[Cl in])}

-61.5 log[(5140 + 0.0512 + 0100) / (55 + 0.05145 + 05)] = -82mV

An electrophysiological technique for recording changes in ion current flowing across the membrane in Amperes is known as...

voltage clamp

A technique for recording ionic currents flowing through single ion channels is known as...

patch clamp

While macroscopic currents recorded with Hodgkin and Huxley's voltage clamp device record current changes at a resolution of milliAmps, microscopic currents recorded during patch clamp experiments can be detected on the order of...

picoAmps

Ion channel activation can occur in response to which of the following...

Ligands

Heat

Voltage

Stretch

"Generalized epilepsy with febrile seizures" is a seizure disorder sometimes caused by mutations in ion channels. Which of the following possible effects of a Na+ channel mutation would be most consistent with causing increased action potential AMPLITUDE?

delayed inactivation of voltage dependent Na+ channels

The largest and most diverse class of ion channels are the...

K+ channels

Which of the following statements regarding the Na+/K+ active transporter is incorrect?

It is electrogenic

It moves three Na+ to the extracellular space for every two K+ moved intracellularly

It utilizes ATP for ion transport

It uses 2% of the brain's total energy consumption

It is an integral membrane protein

it uses 2% of the brains total energy consumption

Which of the following channels allow intracellular signaling pathways to directly modulate electrical signals?

Ca+ activated K+ channels

cGMP gated Na+ channels

At a relatively hyperpolarized Vm of -90mV, opening of inwardly rectifying K+ channels results in...

K+ flow into the cell

Ion channels are typically made of multiple protein subunits with a single transmembrane region.

false

Assume you are studying a neuron with the following properties at 37C....

Permeability of neuron at rest pK:pNa:pCl = 1 : 0.05 : 0.45

[K+]Out=5mM [K+]In=140mM

[Na+]Out=145mM [Na+]In=12mM

[Cl-]Out=100mM [Cl-]In=5mM

The net flow of which ion across the neuronal membrane is making the greatest contribution to the resting membrane potential?

potassium

Assume you are studying a neuron with the following properties at 37C....

Permeability of neuron at rest pK:pNa:pCl = 1 : 0.05 : 0.45

[K+]Out=5mM [K+]In=140mM

[Na+]Out=145mM [Na+]In=12mM

[Cl-]Out=100mM [Cl-]In=5mM

The resting membrane potential of the neuron in question is closest to the electrochemical equilibrium (Ex) of which of the following ions...

chloride

Your lab partner was walking to class and has received a nasty series of bee stings from a mutant strain engineered to express a modified apamin venom. This engineered venom specifically targets potassium channels in the CNS. The pyramidal neurons in your partners cerebral cortex have received a dose of venom that results in a 25% reduction in potassium membrane permeability (pK). Assume you are studying a neuron in your partners cortex that happens to have the same properties as the one in questions 1-2....

Permeability of neuron at rest pK:pNa:pCl = 1 : 0.05 : 0.45

[K+]Out=5mM [K+]In=140mM

[Na+]Out=145mM [Na+]In=12mM

[Cl-]Out=100mM [Cl-]In=5mM

Before the bee stung your partner, the resting membrane potential of the neuron was ____?

-68mv

The Goldman-Hodgkin-Katz equation is used to determine the resting membrane potential.

Em = -61.5 log {(PK[Kin ] + PNa[Nain ] + PCl[Clout ]) / (PK[Kout ] + PNa[Naout ] + PCl[Clin ])}

Em = -61.5 log[(1140 + 0.0512 + 0.45100) / (15 + 0.05145 + 0.455)] = -68 mV

Within a few minutes of the bee sting, the venom crossed the blood-brain-barrier and entered your partners brain. The resting Vm of the neuron you are studying moved to ____?

-65mv

The venom reduced the permeability to potassium from 1 to 0.75, so use the GHK equation with the new K+ permeability of 0.75 to determine the new resting membrane potential.

Em = -61.5 log {(PK[Kin ] + PNa[Nain ] + PCl[Clout ]) / (PK[Kout ] + PNa[Naout ] + PCl[Clin ])}

Em = -61.5 log[(0.75140 + 0.0512 + 0.45100) / (0.755 + 0.05145 + 0.455)] = -65 mV

After your partner was stung, net potassium efflux is ________ in a resting neuron relative to the time period prior to the sting?

decreased

You would like to stimulate this neuron to fire an action potential after being exposed to the venom. Assume a depolarizing stimulus of 25 mV was the minimal amount necessary to trigger an action potential PRIOR to the sting, what is the MINIMAL size of the stimulus necessary to obtain an action potential after the sting?

Prior to the bee sting the resting membrane potential was -68mV. With the 25 mV stimulus, we know that the threshold is -43mV, (-68mV resting + 25 mV stimulus = -43mV new membrane potential that fires an AP). After the bee sting, the resting membrane potential is -65mV. To reach the -43mV threshold, 22mV would be needed.

You have access to two drugs in the lab upstairs that might be useful, Aconitine and Carbamazepine. Aconitine is a sodium channel agonist. Carbamazepine is a sodium channel antagonist. Let us assume that 1 mg of either drug alters sodium permeability accordingly by 1%. Which drug would you administer to fully counteract the effects of the venom on resting membrane potential and possibly save your partner from potentially life threatening seizures?

Carbamazepine, a sodium channel antagonist

How much of the drug you have chosen would you administer to best counteract the effects of the venom?

20mg

ou are back in the lab the next month recording from your partners pyramidal neurons again. Strangely, the neuron exhibits an action potential that has a higher peak depolarized amplitude than normal. You collect some of his DNA and send it for sequencing.

Which of the following gene mutations do you think would be most consistent with the phenotype

A homozygous mutation in the promoter of the KCNQ2 (production of potassium channels) gene that causes reduced expression.

A black widow bit you! Which of the following are potential mechanisms of alpha-latrotoxin effects?

Enhanced calcium independent neurotransmitter release

binding to neuroexins

**Alpha-latrotoxin is a presynaptic neurotoxin that causes a massive discharge of neurotransmitters. It is capable of releasing neurotransmitters, even in the absence of extracellular Ca+ which is normally required (Ca+ independent neurotransmitter release). It binds to two different proteins that mediate this neurotransmitter release, neurexins and CL1.

A quanta of neurotransmitter release is thought to be the result of thousands of vesicles fusing to the pre-synaptic membrane.

false

The fusion of synaptic vesicles to the presynaptic membrane depends heavily upon which ion?

calcium

What types of postsynaptic receptors can contribute to the control of action potential generation in postsynaptic neurons?

Ionotropic receptors

G-protein coupled receptors

Metabotropic receptors

GABA Receptors

Which of the following is an ionotropic receptor for glutamate?

AMPA

NMDA

You are performing a whole-cell patch clamp recording experiment from a cortical neuron in a transgenic mouse that expresses a mutation linked to schizophrenia. The acute slice you are recording from is bathed in a standard perfusion media with TTX, which blocks voltage dependent Na+ channels. Which of the following experimental outcomes is MOST likely when compared to control slices from wild type mice?

decreased RMP

Ion channel activation can occur in response to which of the following...

Neurotransmitter release

Heat

Voltage

Stretch

A postsynaptic potential is...

Dependent on the EREV of the ion channel being activated

What is the most likely effect on synaptic transmission if you were injected with a botulinum toxin?

decreased exocytosis of neurotransmitters

Please answer the following questions about the potential effects of being bitten by a black mamba and exposure to the relevant neurotoxin that blocks Ca2+ current, calciseptine.

What is the likely outcome of exposure to calciseptine?

ataxia

paralysis

breathing difficulty

In the presynaptic space, the flow of which ions would be most disrupted by calciseptine, a smooth muscle relaxant?

calcium

Theoretically speaking, which of the following remedies might have some benefit following calciseptine exposure?

Carbachol, an acetylcholine (ACh) receptor agonist

Sarin, an acetylcholinesterase (AChE) inhibitor

Nicoderm CQ, an agonist at nicotinic acetylcholine (ACh) receptors

You are performing a whole cell patch clamp recording from a cortical pyramidal neuron.

If you set the holding Vm to -70 mV, which of the following is most likely?

you are preparing to assess an AMPA receptor

AMPA and NMDA receptors are both excitatory glutamate receptors. There is a Mg2+ block on NMDA, which is removed when the postsynaptic cell is slightly depolarized. Since the membrane potential is clamped, we will not be able to initiate this depolarization and activation of NMDA receptors. Therefore, we can only observe AMPA receptor function. A current clamp would record voltage output, and this is being held constant with the voltage clamp.

In regard to the neuron from the previous question, you have removed the holding voltage command but accidentally spilled a solution that could contain Ketamine, PCP, or nitrous oxide (all NMDA Receptor antagonists) into your buffer. Which of the following compounds might partly help to counteract the effect?

calcium channel agonist

NMDA Receptors are thought to be important for learning and memory by acting as "coincidence detectors". What does this likely refer to?

NMDA receptors are only open when a cell receives a depolarizing EPSP

What is the most likely effect of benzodiazepines, CNS depressants and GABA agonists, on neurons at rest?

Increased Cl- flux into the neuron

What is the most likely effect of dopamine + clozapine (blocks 5-HT2A serotonin receptors and dopamine receptors) on the response to 5-HT receptor activation?

Effect is dependent on 5-HT receptor subtype

What will likely happen to ion flux in the axon hillock after a neuron has been exposed to 10mM GABA at the distal dendrite and 10mM glutamate on the cell body?

Na+ flux into the neuron

A single shock to the motor nerve innervating the soleus muscle causes a depolarizing EPP of 30 mV in a single muscle fiber. 10 repetitive shocks at 50 Hz causes EPPs that increase in size for the first five shocks, then progressively decrease for the next 5 shocks.

The progressive increase at the beginning of the train of stimuli is an example of synaptic ________ while the decrease is an example of synaptic ________, both of which are mechanisms of ______-term synaptic plasticity.

faciliation, depression, short

In the experiment from question #1, you would like to examine the underlying mechanism. You replace the external perfusion bath with one containing a 50% reduction in calcium. Now, when you apply a shock, the EPP is only 2 mV in amplitude. What is the best explanation for this reduced response?

Reduction in presynaptic release of synaptic vesicles per depolarizing shock.

You decide to continue the experiment on the neuron from question#2 in the reduced [Ca2+]. You stimulate the neuron with 30 repetitive shocks at 50 Hz and find the EPP is larger at the end of the stimulation protocol. Why is this?

[Ca2+] in the presynaptic space increases during repeated stimulation, leading to enhanced synaptic vesicle release per shock at the end of the train. Depression does not occur as it does with a normal extracellular [Ca2+] since the relative number of vesicles that fuse after each shock is reduced. Thus vesicle depletion is difficult to achieve.

Which of the following statements regarding the role of FMRP in hippocampal plasticity as analyzed in question 4 and 5 is most accurate? (FMRP is Fragile X mental retardation protein and results in the neurodevelopmental disorder Fragile X Syndrome.)

FMRP normally limits the number of synaptic vesicles in the reserve pool, but does not regulate facilitation.

The canonical hippocampal circuit consists of _________ projections from the entorhinal cortex to the dentate gyrus, _________ projections from the granule cells to region CA3, and ________ projections from region CA3 to region CA1.

Perforant path, mossy fiber, Schaffer collateral

An important molecular mechanism in the induction of hippocampal LTP is that...

the NMDA receptor acts as a molecular coincidence detector.

Injection of calcium chelators, such as EDTA, into a postsynaptic neuron would most likely have what effect on synaptic plasticity?

LTP would not be observed

Following High Frequency Stimulation of a single CA3 neuron, you are able to record increased synaptic strength in a CA1 neuron. You examine a different CA3 neuron that also targets this CA1 neuron and find no dramatic increase in synaptic strength. This is a good example of what aspect of LTP?

specificity

Which of the following statements about the plasticity of synapses 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.

Changes in synaptic efficacy can occur over time scales ranging from milliseconds to years.

Calcium ions play a central role in at least some forms of synaptic plasticity.

The hallmark of both short-term and long-term synaptic plasticity is that they always increase the strength of synaptic connections.

Which ion contributes the most to the resting membrane potential of our neuron? Why?

K+, the presence of K+ "leak channels" in the membrane