Principles of Neuroscience Lecture 20 Memory II

Question 0

What is LTD?

Answer 0

Lond term depression; the eventual weakening of the connection between neurons
Loss of a memory

Question 1

What is LTP?

Answer 1

Long term potentiation: strengthening between synapses, memory forming

Question 2

Describe the experiment investigating LTP and LTD

Answer 2

A neuron was stimulated with

a. Tetanus
b. low frequency tetanus

In a., there was long term potentiation
In b., there was long term depression

Question 3

Low frequency tetanus stimulation of a neuron results in …

Answer 3

LTD

Question 4

What is the mechanism for LTP?

Outline the steps

Answer 4

1. Glutamate release by the pre synaptic neuron when the synaptic vesicles fuse with the membrane
2. Glutamate binds to NMDA receptors, calcium rushes into the cell
3. Influx of calcium activates protein kinases (CaMKII)
4. Protein kinases phosphorylate and being about the insertion of AMPA in the membrane, and increasing the effectiveness of AMDA already in the membrane

Question 5

Differentiate between AMPA and NMDA receptors

Answer 5

AMPA: excited by glutamate
NMDA: unblocked by glutamate, calcium rushes through

Question 6

What is CaMKII?

Answer 6

Calcium-calmodulin dependent Kinase II

Question 7

What are the different regions of CaMKII?

Answer 7

Catalytic

Regulatory

Question 8

What is the activity of CaMKII when it is phosphorylated?

Answer 8

It is constitutively active (that is, until a phosphatase removes the phosphate)

Question 9

Describe the multimer structure of CaMKII?

Answer 9

The CaMKII are found in rings.

Once Ca/calmodulin disown its some of them, they all become activated and phosphorylated.

Question 10

What is CaMKII’s role in LTP?

Answer 10

When there is calcium influx into a cell, the calcium activates and brings about phosphorylation of the CaMKII

Question 11

What is required for true long term memory?

Answer 11

Protein synthesis alteration

Receptor deposition, receptor sensitivity and phosphorylation aren’t enough for long term change

Question 12

Describe how protein synthesis can be altered in memory storage

Answer 12

1. CREB-2 replaced with CREB-1 when there is activity in a certain neuron
2. CREB-1 is phosphorylated, and that gene will undergo transcription

Question 13

What are the different ways that calcium can enter a neuron?

Answer 13

1. NMDA receptor
2. Intracellular stores: inside the cell, glutamate binds to a receptor on the ER membrane, prompting Ca release from the ER
3. Back propagating dendritic action potentials open voltage gated Ca channels

Question 14

What is spike timing dependent plasticity?

Answer 14

This is when the dependence of memory formation (LTP, LTD) on the timing of the action potential

Question 15

Describe how LTP is dependent on spike timing dependent plasticity

Answer 15

If the action potential occurs after EPSP –> LTP

Question 16

Describe how LTD is dependent on spike timing dependent plasticity

Answer 16

If the action potential occurs before EPSP –> LTD

Question 17

What is EPSP?

Answer 17

Excitatory post-synaptic potential

This is when there is depolarisation of the post-synaptic cell due to ion channels opening and positively charged ions flowing into the cell.