Question 1

How does ChR2 activate neurons?

Accepted Answer

A)  Blue light causes a conformational change in a rhodopsin protein which causes the channel to open. This results in a nonselective cation current that allows more Na+ influx than K+ efflux, depolarizing the neuron. 
B)  Blue light causes a conformational change in a rhodopsin protein which causes the channel to open. This results in a nonselective cation current that allows more K+ efflux than Na+ influx, depolarizing the neuron. 
C)  Blue light activates the rhodopsin protein that activates a G protein which opens a nonselective cation current which allows more Na+ influx than K+ efflux, depolarizing the neuron. 
D)  Blue light activates the rhodopsin protein that activates a G protein which opens a nonselective cation current which allows more Na+ influx than K+ efflux, hyperpolarizing the neuron. 
E)  Blue light activates the rhodopsin protein that activates a G protein which opens a nonselective cation current which allows more K+ efflux than Na+ influx, depolarizing the neuron.
F) Blue light activates the rhodopsin protein that activates a G protein which opens a nonselective cation current which allows more K+ efflux than Na+ influx, hyperpolarizing the neuron.

Question 2

In the experiment in Figure , the motor neuron of a muscle expressed the P2X2 transgene and the response in the muscle was recorded. Why did application of ATP activate the muscle?  Figure

Accepted Answer

A)  Addition of ATP activated of the P2X2 channel which directly increased transmitter release by moving vesicles to the presynaptic membrane. 
B)  Addition of ATP resulted in opening of the P2X2 channel and an influx of sodium, which activated the motor neuron, releasing neurotransmitter and activation of the muscle. 
C)  Addition of the resulted in activation of the P2X2 protein, a G protein coupled receptor. Once activated the receptor increased the probability of neurotransmitter release and activated the muscle. 
D)  Addition of ATP resulted in activation of the ATP receptor, a G protein coupled receptor. Once activated, this G protein indirectly activated P2X2, which increased the probability of neurotransmitter release from the motor neuron and activated the muscle.

Question 3

What is one of the potential advantages that human genome sequencing will have on neuroscience?

Accepted Answer

A)  It will allow scientists to better correlate genetic phenotypes with mental illnesses. 
B)  It will allow scientists to manipulate genes and cure mental illnesses. 
C)  It will allow scientists to express light-activated channels into specific neurons to help cure diseases. 
D)  It will allow scientists to design babies free of disease.
Genetic and Molecular Techniques

Question 4

Trans-synaptic tracing uses rabies virus to spread across synapses. In the scenario in Figure, what would happen if the presynaptic cell also expressed the glycoprotein transgene?  Figure

Accepted Answer

A)  The virus spread would not be limited to presynaptic neurons of the starter cells. 
B)  The virus would not be limited to how many neurons it could infect. 
C)  The virus would not be able to infect other synaptic partners and would stay in the neuron presynaptic to the starter neuron. 
D)  The virus would not be able to spread to any synaptic partners and would stay in the starter cell.

Question 5

What is the difference between a knock-in and a knockout?

Accepted Answer

The answer of What is the difference between a knock-in...

Question 6

Deep brain stimulation is a technique used to help people with different diseases, including Parkinson's. People with Parkinson's disease have difficulties with movement due to a decrease in dopaminergic input to the basal ganglia. For Parkinson's patients the subthalamic nucleus (STN) is stimulated and this relieves some of the symptoms associated with the disease. However, it is not clear if stimulation of the nucleus stimulates neurons within the STN, or inputs to the STN (from the cortex). Outline an experiment in a mouse that could look at the difference between activation of the STN and activation of inputs to the STN.
Behavioral Analyses

Accepted Answer

The answer of Deep brain stimulation is a technique used...

Question 7

An important principle in neuroethology is to select a model system with a robust behavior. Why is this an important concept when considering which animal to study?

Accepted Answer

The answer of An important principle in neuroethology is to...

Question 8

What does functional magnetic resonance imaging measure?

Accepted Answer

A)  The synchronous electrical activity of thousands of neurons 
B)  The blood flow near excited neurons 
C)  The activity of glia near excited neurons 
D)  The magnetic activity of electrically excited neurons

Question 9

What does a Nissl stain tell you? Choose all that apply.

Accepted Answer

A)  The location of neurons and glia 
B)  The location of fiber tracts (axons) 
C)  The connectivity between two neurons 
D)  The identity of a neuron's neurotransmitter 
E)  The location of cell nuclei

Question 10

How does halorhodopsin (NpHR) inactivate neurons?

Accepted Answer

A)  Halorhodopsin is activated by blue light, which causes a nonselective cation current which allows more K+ efflux than Na+ influx, hyperpolarizing the neuron. 
B)  Halorhodopsin is activated by blue light, which results in increased permeability to chloride, effectively silencing the cells. 
C)  Halorhodopsin is activated by yellow light, which causes a nonselective cation current which allows more K+ efflux than Na+ influx, hyperpolarizing the neuron. 
D)  Halorhodopsin is activated by yellow light, which results in an increased transportation of chloride across the membrane, effectively silencing the cells.

Question 11

Which of the following are ways to activate neurons or groups of neurons? Choose all that apply.

Accepted Answer

A)  Lesions 
B)  Stimulation 
C)  Overexpression of Kir 
D)  Expression of ChR2 
E)  Expression of halorhodopsin
F) ATP activation

Question 12

You are studying a new species of bird and want look at areas of the brain that are sexually dimorphic. Which technique is best for this?

Accepted Answer

A)  CLARITY 
B)  Nissl stain 
C)  Confocal microscopy 
D)  Intracellular dye fills 
E)  Electron microscopy

Question 13

The CASPR/Cas9 system is a new, very powerful technique that can knockout genes in mice, flies, and animals that are not accessible to genetic manipulation. If you are trying to remove expression of a presynaptic protein you need to add a guide RNA and Cas9. Why do you need a guide RNA? Choose all that apply.

Accepted Answer

A)  The guide RNA guides the Cas9 to the loxP site on the target DNA. 
B)  The guide RNA targets the selected DNA and brings Cas9 to the DNA target site. 
C)  The guide RNA guides CRISPR to the Cas9 protein to target the selected piece of DNA. 
D)  CRISPR is inserted into the genome where the guide RNA guides Cas9 to the deletion site.

Question 14

What is the advantage of an extracellular recording over an intracellular recording?

Accepted Answer

The answer of What is the advantage of an extracellular...

Question 15

An experiment reversed Rett symptoms by restoring MeCP2 expression in young mice. Overexpression of MeCP2 causes significant neurological defects so the investigators used an interesting technique where they inserted a transcription stop site flanked by two loxP sites in between the transcription start site and the coding region.
A. What is the advantage of this technique?
B. The investigators then used tamoxifen-inducible CreER excision of the transcription stop site. What was the function of this procedure?

Accepted Answer

The answer of An experiment reversed Rett symptoms by restoring...

Question 16

One way to knock-down protein expression is by RNA-interference (RNAi).
A. What is the advantage of this system over a more common knock-out?
B. Why do you need double-stranded RNA for gene knockdown by RNAi?

Accepted Answer

The answer of One way to knock-down protein expression is...

Question 17

Making a complete map of all the connections in a circuit is sufficient to tell you how the circuit works. Defend your answer.
Recording and Manipulating Neuronal Activity

Accepted Answer

A) True 
 B)False

Question 18

Which is/are the correct statement(s) about confocal and/or light-sheet microscopy?

Accepted Answer

A)  Confocal microscopy detects fluorescence from a single focal plane of tissue. 
B)  Confocal microscopy focuses light on a specific focal plane in a section of tissue. 
C)  Light-sheet microscopy detects fluorescence from a single focal plane of tissue. 
D)  Light-sheet microscopy uses a large objective lens to focus light on a large sheet of tissue. 
E)  Confocal microscopy is faster than light-sheet microscopy.
F) Both require fluorescent markers in the tissue.

Question 19

All of the techniques described need appropriate controls. In knockout animals, many investigators will try and 'rescue' the phenotype by adding back the knocked-out protein. Why is this a critical control and what is the expected result, in general?

Accepted Answer

The answer of All of the techniques described need appropriate...

Question 20

The chapter started with a quote from Sydney Brenner "Progress in science depends on techniques, new discoveries, and new ideas, probably in that order." Based on what you have read in this chapter and the entire textbook do you agree or disagree with this statement??

Accepted Answer

The answer of The chapter started with a quote from...

Exam 13: Ways of Exploring