Question

You are conducting a research project that involves studying donated human nervous system tissue. You are trying to determine whether a drug your lab has tested in mice has the same effect on neuronal signaling in human brain tissue.

You’ve designed an experiment in which you will be extracting neurons from different areas of the brain or brainstem from the donated human tissue that are known to contain cells that produce either dopamine, norepinephrine, or serotonin.

You stain the presynaptic cells in the petri dishes from one brain/brainstem region to see if they contain tyrosine hydroxylase, and you observe that they do. You then add a drug that reduces the activity of dopamine β-hydroxylase (DBH) but observe no effect on EPSPs at this synapse.

Select the brain/brainstem area below where these cells were most likely extracted from.

	a.	Raphe nuclei
	b.	Locus coeruleus
	c.	Ventral tegmental area
	d.	Nucleus accumbens
	e.	Cerebellum
	f.	None of the above

Now that you’ve figured out which brain/brainstem area the neurons in the first petri dish are from, there are only two options left for the other two petri dishes. Per the undergrad’s advice, for the next petri dish you add an enzyme that depletes ascorbic acid, and you observe that there is a decrease in the size of the EPSPs elicited when you stimulate the presynaptic neuron.

Select the brain/brainstem area below where these cells were most likely extracted from.

	a.	Raphe nuclei
	b.	Locus coeruleus
	c.	Ventral tegmental area
	d.	Nucleus accumbens
	e.	Cerebellum
	f.	None of the above

Now that you have sorted out the petri dishes, you have started your experiments. However, you soon realize your new data suggest that the drug you are testing has a completeley different effect on human brain tissue than it does in mice. In fact, it seems that in humans its effect does not involve monoaminergic signaling at all.

Which of the following would be evidence of this?

	a.	Applying the drug causes IPSPs in all of the tissue samples
	b.	Blocking VIAAT blocks the effect of the drug
	c.	Applying the drug causes EPSPs in tissue samples containing neurons from the raphe nuclei
	d.	Applying the drug causes IPSPs in tissue samples containing neurons from the locus coeruleus
	e.	Blocking VIAAT does not change the effect of the drug

Answer 1

1) The correct option is : e

The adrenal medulla that contains the tyrosine hydroxylase and dopamine immunosensitive axons lies in the cerebellum.

2) The correct option is : d

The ascorbic acid is found in the glial reservoirs of the nucelus accumbens to the side of synaptic cleft.

3) The correct option is : b

Blocking VIAAT   blocks the effect of the drug which suggests that the drug is not acting directly to alter the neurotransmitter release.