Exam 13: Ways of Exploring

How does ChR2 activate neurons?

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

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

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

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

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

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?

What does functional magnetic resonance imaging measure?

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

How does halorhodopsin (NpHR) inactivate neurons?

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

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?

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.

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

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?

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?

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

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

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?

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??