Lecture 33-35: Neuroplasticity

Question 1

Short term potentiation is mainly due to

Answer 1

the delay of calcium release from synaptotagmin

Question 2

Three ways to increase strength of synapses

Answer 2

1. Increase in Pr (Probability of release) of vesicles 2. Increase in N (number of release sites) i.e. insertion of new active zones into synapse 3. Increase in q (quantal size)

Question 3

How can you achieve an increase in probability of release of vesicles?

Answer 3

More Ca2+ flux into the presynaptic terminal More docked vesicles

Question 4

How can you achieve an increase in N (number of release sites)?

Answer 4

Unsilencing of synapses (pre or postsynaptic) Production/synthesis of new synapses

Question 5

How can you achieve an increase in q (quantal size)?

Answer 5

Increase in AMPA receptors (only if AMPA receptors of that synapse are saturated) Change in AMPA receptor kinetics

Question 6

True or false: Most LTP is associative.

Answer 6

True.

Question 7

True or false: Associative LTP only occurs if presynaptic neuron fires at the same time as the postsynaptic neuron

Answer 7

False, associative LTP occurs if presynaptic neuron fires just before postsynaptic neuron (within 1 millisecond)

Question 8

True or false: Non-associative LTP requires NDMA receptors, but associative does not.

Answer 8

False, it is the associative that requires NDMA receptors.

Question 9

The connection between the entorhinal cortex and the dentate gyrus is called the

Answer 9

Perforant pathway

Question 10

The connection between the dentate gyrus and region CA3 is called the

Answer 10

Mossy fibre pathway

Question 11

The connection between region CA3 and region CA1 is called the

Answer 11

Schafer collateral pathway

Question 12

The connection between region CA1 and the entorhinal cortex is called the

Answer 12

Subicular return pathway

Question 13

Which pathway does not follow the curvature of the hippocampus?

Answer 13

Perforant pathway (it perforates the two cell layers)

Question 14

When a glutamate vesicle is released, how many glutamate molecules are released?

Answer 14

When a glutamate vesicle is released, 5000 glutamate molecules are released which bind to all 3 types of glutamate receptor

Question 15

Effects of NMDA activation

Answer 15

Ca²⁺ entry via NMDA receptors leading to:

1. Ca²⁺ release from intracellular stores through activation of PKC
2. Ca²⁺ entry via VACCs, as at all synapses
3. Activation of CaCam Kinase II (by Ca²⁺)
4. Activation of PKA and PKC (by Ca²⁺ and DAG)

Question 16

Mechanisms of autonomously active CaMKII and PKC

Answer 16

Phosphorylation of AMPA receptors - increasing their conductance

Mediate insertion of additional AMPA receptors into the postsynaptic membrane (this event is independent of protein-synthesis)

Phosphorylation of PSD-95 (receptor clustering protein) thus causing a greater clustering of AMPA receptors

Question 17

Retrograde messengers

Answer 17

Arachidonic acid

Nitric oxide

Carbon monoxide

Question 18

Effects of NMDA stimulation

Answer 18

Change in probability of vesicular release (earliest phase of LTP)

Change in size of current producd by each AMPA receptor

Change in number of AMPA receptors

Change in the electrical excitability of the dendritic membrane

Production of a new dendritic spine

Question 19

True or false:

LTP in the mossy fiber pathway is NMDA receptor-independent.

Answer 19

True. It is a type of non-associative LTP.

Question 20

Which rhythm is specific to the hippocampus?

Answer 20

Theta (4-8 Hz)

Question 21

60% of CA3 pyramidal neurons are

Answer 21

place cells