Kaplan lesson book problem 14 pg270

[FancyFloss]

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After the learning process of habituation, neurons receiving a stimulus respond with less response than they would have prior to habituation. Which of the following effects of repeated stimulation is a possible explanation for habituation?

A. Permanent closure of calcium channels in the terminal membrane.
B. Increase in the number of neurotransmitter receptors in the postsynaptic membrane.
C. Decrease in the concentrations of neurotransmitter-degrading enzymes in the synapse.
D. Neurotransmitter vesicles fusing with the terminal membrane in response to lower excitatory potentials.
E. Increase in the amount of neurotransmitter released per action potential.

I don't have the answer since my Kaplan online subscription ended so any help as to which is right and why would be awesome.

 

[dawg289]

I think the answer is B. See if my logic makes sense.

Habituation is the process of learning to ignore meaningless stimuli. You might be able to reason this out based on the first sentence, but it's a good term to know. I see "neurons receiving a stimulus respond with less response"...so we're looking for a mechanism that results in neurons firing with lower activity.

A. (no) No Ca+ channels, no influx of Ca++ to make vesicles fuse...but this would cause no response, but the question said less response.
B. (yes) More neurotransmitter receptors means that each one is being activated less frequently, leading to lower levels of activity.
C. (no) Lower enzyme levels means the nt would hang around longer, which would increase activity.
D. (no) Lower excitatory potentials means neurotransmitter vesicles are more sensitive to fusing, which would increase activity
E. (no) More nt per action potential would increse activity

 

[FancyFloss]

Thanks, I was leaning towards B also but without the answer I needed some verification.

 

[TheEpicFruitCake]

Wait, how would increasing neurotransmitter receptors cause there to be less of a response? Isn't this downregulation; the decrease of neurotransmitter receptors?

 

[FancyFloss]

Yea but there isn't an option for a decrease in neurotransmitter receptors other than the permanent closure of calcium channels in the terminal membrane and since that causes 0 response it can't be the answer if there is less of a stimulus rather than no stimulus. This is a Kaplan question so there is that. Kaplan strikes again

 

[TheEpicFruitCake]

Well B makes absolutely no sense because it is the exact opposite. Increasing neurotransmitters INCREASES response. "A" is the only one even remotely correct.

"We have noted that release of neurotransmitters is triggered by a rise in the intracellular Ca2+ concentration following opening of voltage-gated Ca2+ channels. Measurements of Ca2+ movements in the Aplysia siphon sensory neuron have shown that habituation results from a decrease in the number of voltage-gated Ca2+ channels that open in response to the arrival of anaction potential at the axon terminal, thus reducing the amount of glutamate neurotransmitter released. Habituation does not affect the generation of action potentials in the siphon sensory neuron or the response of the receptors in the postsynaptic cells."

source: http://www.ncbi.nlm.nih.gov/books/NBK21648/
Molecular Biology 4th edition

edit: and yes we are dealing with kaplan here so who knows, maybe there is no correct answer hahaha

 

[emminent]

Well B makes absolutely no sense because it is the exact opposite. Increasing neurotransmitters INCREASES response. "A" is the only one even remotely correct.

"We have noted that release of neurotransmitters is triggered by a rise in the intracellular Ca2+ concentration following opening of voltage-gated Ca2+ channels. Measurements of Ca2+ movements in the Aplysia siphon sensory neuron have shown that habituation results from a decrease in the number of voltage-gated Ca2+ channels that open in response to the arrival of anaction potential at the axon terminal, thus reducing the amount of glutamate neurotransmitter released. Habituation does not affect the generation of action potentials in the siphon sensory neuron or the response of the receptors in the postsynaptic cells."

source: http://www.ncbi.nlm.nih.gov/books/NBK21648/
Molecular Biology 4th edition

edit: and yes we are dealing with kaplan here so who knows, maybe there is no correct answer hahaha

LOL that last line made me laugh pretty hard

 

[FancyFloss]

edit: and yes we are dealing with kaplan here so who knows, maybe there is no correct answer hahaha

Exactly my thoughts when taking any Kaplan test.

 

[FancyFloss]

Shoutout to literally anyone with the answer from Kaplan and their explanation cuz I want to see how Kaplan worms their way out of this one.

If they had a profile on SDN we would all rip them a new one