exam 1 Lecture 1 LTP intro

Question 1

What is the innervation from the dentate gyrus to the C1 neurons?

Answer 1

The dentate gyrus sends its axons to the CA3 neurons. The CA3 neurons sends its axons called the schaffer collaterals to the CA1 neurons synapse with the apical dendrites of the CA1 neurons.

Question 2

What is a tetanus and what does it do?

Answer 2

A tetnus is an intense stimulation that makes the presynaptic neuron release more glutamate. It causes PTP then LTP.

Question 3

What is PTP (post tetanic potentiation)? How long does it last for?

Answer 3

Extreme response due to lots of calcium release. Short lived response.

Question 4

What is LTP?

Answer 4

LTP makes the post synaptic neuron more receptive to glutamate, and LTP has a higher EPSP. Strengthens synapses between neurons. The enhanced responsiveness of a subset of inputs to stimuli. Post synaptic phenomenon.

Question 5

How do you get around the fact that the EPSP is contaminated with action potential?

Answer 5

You measure the slope of the EPSP, which is voltage/time. The slope is proportional to the magnitude of the EPSP.

Question 6

What is the EPSP?

Answer 6

The EPSP tells you the likelihood of a neuron firing an action potential.

Question 7

What does measuring the EPSP have anything to do with learning and memory?

Answer 7

You stimulate axons and drive the post synaptic cell by converging inputs. The convergence enhances the inputs because the response is that those inputs are enough to drive the cell. Only the inputs that receive the excitation get enhanced. Others will get reduced. Reduction in inputs results in loss of learning and memory.

Question 8

What type of neuron that we are studying releases glutamate?

Answer 8

The Schaffer Collaterals of the CA3 neurons.

Question 9

What type of phenomenon is PTP and where does it occur?

Answer 9

PTP is a pre-synaptic phenomenon that occurs at the CA1 synapses.

Question 10

What is the rapid release pool of glutamate?

Answer 10

The RRP is the release pool that is in the zone of activation. Proteins in the plasma membrane links the RRP to the voltage gated calcium channels. Following an action potential, calcium enters the pre-synaptic cell through those voltage gated calcium channels. The RRP is the first to sense the change in calcium levels.

Question 11

What is the reserve pool of glutamate and how is it released?

Answer 11

The reserve pool is farther down into the cell and is used when the RRP is used up.

1. Continuous input increases the calcium in the presynaptic terminal.
2. calcium activates calmodulin.
3. Calmodulin activates M2.
4. M2 slowly releases the slow release vesicles into the active zone area and they associate with the voltage gated calcium channels.

Question 12

Why is M2 is unlikely to be involved in the movement?

Answer 12

There are other myosins that are better designed to be involved in the movement of vesicles.

Question 13

What neurotransmitter is released as a response to the tetanus?

Answer 13

Glutamate

Question 14

Why does PTP stop as soon as the tetanus stops? What happens after PTP and tetanus stop?

Answer 14

The axon is efficient at pumping calcium out without the stimulus. Calcium is good at leaving so you don’t need a stimulus anymore when the calcium itself is good. After PTP and tetanus stop, LTP starts.

Question 15

Why is calcium a good second messanger?

Answer 15

The axon terminals are good at removing calcium.

Question 16

Is LTP post synaptic or presynaptic?

Answer 16

Post synaptic

Question 17

Where do Schaffer collaterals synapse? (be specific)

Answer 17

On the dendritic spines of CNS neurons. They synapse on the apical dendrites of the CA1 neurons.

Question 18

Where are the dendritic spines on the dendrites located?

Answer 18

They are at the site where one glutamate axon forms a synapse.

Question 19

How do you observe spine dynamics?

Answer 19

You fill the cell with a fluorescent molecule.

Question 20

Why is there ATP in the presynaptic specialization (presynaptic neuron)?

Answer 20

Calcium pumps need ATP to pump calcium out.

Question 21

From where does a spine receive excitatory input?

Answer 21

From one presynaptic bouton, where one glutamate axon forms a synapse.

Question 22

Are spines dynamic?

Answer 22

Yes. They are affected by LTP.

Question 23

What happens at the spine?

Answer 23

The spine receives glutamergic inputs. It is where post synaptic changes (selected) take place so it is a post synaptic phenomenon.

Question 24

Why are spines advantageous?

Answer 24

Dendritic spines are compartmentalized so inputs have their own volume that they can control, which individualizes the responsiveness to the inputs.

Question 25

Can you induce LTP with low frequency stimulation? If so, how?

Answer 25

Yes. You pair it with an action potential or a post synaptic depolarization in a process called associativity.

Question 26

What determines the net flow of sodium and calcium into the cell?

Answer 26

Concentration and electrical gradients.

Question 27

What ion determines the resting membrane potential and why?

Answer 27

K+ because the membrane is more permeable to K+ than any other ion. K+ has more leak channels than Na+ and Cl-, so they influence the membrane potential less.

Question 28

Why doesn’t Cl- enter the cell and contribute to the resting membrane potential?

Answer 28

It has less leak channels, and the inside of the cell is already more negative than the outside, and Cl- is negatively charged.

Question 29

Why doesn’t Ca2+ contribute to the membrane potential?

Answer 29

There are no calcium leak channels.

Question 30

Do AMPARs pass K+?

Answer 30

Yes, but not much as the driving force on K+ is not high.

Question 31

Is the driving force on Ca2+ and Na+ large?

Answer 31

Yes.

Question 32

Where are the two pinhole places in fluorescence and their purpose?

Answer 32

1. Between the object and light source to let maximum amount o flight possible onto the specimen.
2. Detector and specimen to reduce out of focus light since the specimen emits light spherically.

Question 33

How confocal microscopy is used

Answer 33

check notebook