Psyc 215A Unit 2 Lecture 5: Biological Basis Of Learning And Memory

Front 1

Neural Plasticity

Back 1

The ability of the nervous system to be modified after birth.

Front 2

How does neural plasticity effect synapse signalling?

Back 2

It causes changes that can strengthen or weaken signalling at a synapse.

Front 3

What are the steps of LTP?

Back 3

One or more axons fire a rapid series of stimuli.

The burst of stimulation leaves some of the synapses potentiated for minutes, days, or weeks.

Hint 3

2

Front 4

What is so special about a potentiated synapse?

Back 4

It is more likely to elicit an action potential.

Front 5

Do stimuli have to generate action potentials in LTP?

Back 5

No.

Front 6

How do we know LTP works for learning and memory?

Back 6

Drugs that impact learning often have parallel effects on LTP.

Learning can produce LTP-like changes.

LTP effects are greatest in brain areas involved in learning and memory.

LTp is elicited by high-frequency electrical stimulation of the presynaptic neuron and mimits normal neural activity.

Hint 6

4

Front 7

What are the three steps of LTP?

Back 7

Induction (learning)
Expression (memory)
Maintenance (recall)

Hint 7

3, durr

Front 8

How do mice show improved learning and memory from LTP?

Back 8

Mice with little LTP have trouble with MWM. Drugs that enhance LTP can also enhance MWM.

Hint 8

2

Front 9

What does Glutamate act on?

Back 9

The receptors AMPA and NMDA on the postsynaptic membrane

Hint 9

2

Front 10

AMPA

Back 10

A postsynaptic receptor permeable to Na+

Front 11

NMDA

Back 11

A postsynaptic receptor normally blocked by Mg2+ but permeable to Na+ and Ca2+

Hint 11

2

Front 12

What must happen for NMDA receptors to open?

Back 12

Postsynaptic membrane must be depolarized, to displace Mg2+ from receptor pore (strong stimulus)
Glutamate must activate it from the presynaptic neuron (weak stimulus)

Hint 12

2

Front 13

What is meant by saying that NMDA receptors as associative?

Back 13

That the strong and weak stimuli involved in opening the receptors are paired. Both must occur.

Front 14

How does induction of LTP occur?

Back 14

High frequency stimulation will activate both AMPA and NMDA receptors and the threshold for LTP will be reached.

Hint 14

2

Front 15

What happens after NMDA receptors open, regarding expression and maintenance of LTP?

Back 15

Ca2+ enters the postynaptic neuron and alters it.

Front 16

How does Ca2+ alter the postsynaptic neuron?

Back 16

Increases the responsiveness of AMPA receptors to glutamate.

Forms new AMPA receptors.
Causes retregrade messengers (eg, NO) that trigger more glutamate release from presynaptic neuron.

Hint 16

3

Front 17

How long is the LTP potentiated response sustained for?

Back 17

forevs

Front 18

Facts about LTP storage and recall

Back 18

LTP causes both pre- and postsynaptic changes.

LTP is only seen in synapses where it was induced.

Protein synthesis (structural changes) underlies long-term changes (maintenance) (eg intertion of more AMPA receptors into the membrane)

LTP begins in the postsynaptic neuron,, which signals the presynaptic neuron.

Astrocytes (not just neurons) are also involved in LTP.

Hint 18

5

Front 19

Hypothesis for Induction of LTP

Back 19

Due to timulation of NMDA receptors.

Due to cascade of Ca2+ dependent processes.

Hint 19

2

Front 20

Hypothesis for Expression of LTP

Back 20

Due to AMPA receptor proteins (eg, insertion of new receptors, relocation of receptors, change in receptor properties)

Hint 20

3

Front 21

Hypothesis of Maintenance of LTP

Back 21

Due to structural modifications (eg, new synaptic contacts, protein synthesis)

Hint 21

2

Front 22

What is LTD?

Back 22

Synaptic plasticity is bidirectional - low frequency, depression sets in.

Hint 22

2

Front 23

Where is LTP mediated?

Back 23

Research has been focussed on NMDA-receptor mediation in the hippocampus, but we know that LTP is mediated by different mechanisms elsewhere as well.

Hint 23

2