Lectures 1 - 6 Tutorial Questions

Question 1

Which of the following statements is true?

• Camillo Golgi, in his Neuron Doctrine, first proposed that neurons communicate information unidirectionally.
• Dendritic spines comprise all postsynaptic sites in the CNS.
• There is no correlation between the size and strength of dendritic spines.
• In axons, kinesin motors transport cargo towards the distal end.
• Most neurons have more than one axon.

Answer 1

In axons, kinesin motors transport cargo towards the distal end.

Question 2

Which of the following statements is not true?

• Astrocytes play an important role in synaptic formation and maintenance.
• Schwann cells myelinate only one axon, but one axon can be myelinated by many Schwann cells.
• All cells in the brain originate from radial glia.
• Microglia originate from the mesoderm (bone marrow).
• Multiple sclerosis is due to demyelination of the central nervous system.

Answer 2

All cells in the brain originate from radial glia.

Question 3

In Young’s squid giant axon preparation (i.e. standard conditions), how much would one have to change [K] outside of the neuron to get a 58 mV decrease in Ek?

• Increase by a factor of 2.
• Decrease by a factor of 2.
• Increase by a factor of 10.
• Decrease by a factor of 10.
• Decrease by a factor of 5.8.

Answer 3

Decrease by a factor of 10.

Question 4

Which of the following is not a manner in which one could change the driving force upon an ion?

• Change the intracellular concentration of the ion.
• Changing the diameter of the membrane.
• Change V_m by injecting current.
• Change the extracellular concentration of the ion.
• None of the above.

Answer 4

Changing the diameter of the membrane.

Question 5

You generate an organism whose nodes of Ranvier on the axons of its motor neurons are abnormally spaced apart, such that the organism shows limited mobility. In a hypothetical world, what would be the best way to overcome this defect?

• Increase the myelination around the axons of its motor neurons.
• Increase the density of voltage-gated ion channels.
• Subject the organism to a high Na⁺ environment.
• Increase the size of excitatory post-synaptic potentials.
• Tell the organism to move less to conserve energy.

Answer 5

Increase the myelination around the axons of its motor neurons.

Question 6

You perform voltage clamp experiments upon axonal preparations taken from two different frogs, Frog A and Frog B, in the presence of TTX. As you analyze your recordings, you notice that the conductance of the current measured in Frog B is significantly smaller compared to that of Frog A for each Vm. Which of the following is a reasonable explanation for why this might be?

• Frog B expresses fewer voltage-gated K⁺ channels than Frog A.
• The extracellular [K⁺] surrounding Frog B happened to be greater than that surround Frog A.
• Frog B expresses fewer voltage-gated Na⁺ channels than Frog A.
• The extracellular [Na⁺] surrounding Frog B happened to be lower than that surrounding Frog A.
• The extracellular [Na⁺] surrounding Frog B happened to be greater than that surrounding Frog A.

Answer 6

Frog B expresses fewer voltage-gated K⁺ channels than Frog A.