4- Declarative Learning Flashcards
What does declarative learning look at?
Cellular and molecular bases of long-term memory
What is the crucial brain structure involved in declarative memory?
The hippocampus
What was one of the first brain structures to develop?
The hippocampus
What structure do all animals share?
The hippocampus
What is the key role of the hippocampus?
Forming new memories
What 3 mechanisms are controlled by the hippocampus?
Long-term potentiation
Long-term depression
cAMP-response-element-binding regulated protein
Why was HM studied?
Couldn’t form any new memories
When does long-term potentiation (LTP) occur?
With high frequency stimulation of CA1 neurons via Schaffer collaterals
When are Schaffer collaterals stimulated?
When taking in new information
What is the main mechanism used in LTP?
Glutamatergic synapses
Which neurotransmitter is used by glutamatergic synapses?
Glutamate
What characterises glutamate?
As the most common excitatory neurotransmitter in the CNS
What are the 2 types of glutamate postsynaptic receptors?
AMPA receptors and NMDA receptors
How is the LTP glutamatergic mechanism started?
By frequent presynaptic action potentials
What does the frequent presynaptic action potentials cause in LTP?
Strong glutamate release
How is postsynaptic depolarisation (increase in sodium ions) caused in LTP?
Glutamate binding to AMPA receptors
How does unblocking occur in LTP?
Glutamate binds to NMDA receptors
What is created by a strong Ca2+ influx? (LTP)
Protein kinase
What is the fast mechanism involved in protein kinase creation? (LTP)
Relocation of new AMPA receptors to postsynaptic
What is the slow mechanism involved in protein kinase creation (LTP)?
Activating gene transcription
What 2 processes are triggered when gene transcription is activated? (LTP)
Protein synthesis and synapse sprouting
What is the overall response from glutamatergic synapses in long-term potentiation?
More efficient connection
What is a second mechanism involved in long-term potentiation?
Protein synthesis
What is the main aspect of the protein synthesis mechanism? (LTP)
A strong calcium ion influx creating protein kinase
Why is the protein synthesis mechanism slow? (LTP)
Gene transcription is activated via phosphorylating transcription factors
What experimental evidence demonstrates protein synthesis in long-term potentiation?
Inhibiting protein synthesis means more postsynaptic potentials are excited
What is the third mechanism of long-term potentiation?
cAMP-response-element-binding transcription factor (CREB)
What are the 3 processes involved in the CREB mechanism? (LTP)
- CREB-2 represses transcription
- CREB-1 replaces CREB-2
- Protein kinase A activates CREB-1 to cause transcription
What is the fourth mechanism of long-term potentiation?
Transcription
What experimental evidence demonstrates transcription in LTP?
Knocking out CREB transcription factor
What was found by knocking out a CREB transcription factor? (LTP)
Long-term but not short-term spatial memory was impaired
When does long-term depression (LTD) occur?
In low frequency stimulation of CA1 neurons via Schaffer collaterals
What cause does long-term depression have?
Not be able to effectively learn long-term
What is the mechanism of LTD?
Glutamatergic synapses
How does the glutamatergic mechanism of LTD begin?
Rare presynaptic action potentials causing reduced firing
What is caused by rare presynaptic action potentials? (LTD)
Weak release of glutamate
How is postsynaptic depolarisation caused? (LTD)
Glu binding to AMPA receptors
What does a weak influx of Ca2+ create? (LTD)
Protein phosphate
What does protein phosphate creation cause? (LTD)
Internalisation of AMPA receptors from postsynaptic membrane
What is the result of the glutamatergic synapse mechanism of LTD?
Less efficient connection
What is the cause of more activation and more distribution?
We are more likely to link information long-term
Why do we remember a stimulus?
Neurons encode a stimulus
Why do we have a problem recognising competing inputs?
None are able to elicit an action potential
How do we learn to recognise stimuli?
We pay attention to a certain stimulus
When is LPD created by competing inputs?
One stimulus is recognised on its own
When is LTP created by competing inputs?
Other two stimuli are cooperative
Why can the first stimulus not elicit a response?
Due to LDP
Why can the other two stimuli alone not elicit a response?
Due to LTP
What are important mechanisms underlying synaptic plasticity?
LTP and LTD
How do LTP and LTD underlie synaptic plasticity?
Via controlling Ca2+ influx, creating protein kinase/photophatase balance
What is there with a high frequency/correlated stimulus, and what does this cause?
Unblocked NMDA receptor, causes Ca2+ influx that produces kinase
What response is there with a high frequency/correlated stimulus?
A more efficient connection
What is there with a low frequency/uncorrelated stimulus and what does this cause?
Blocked NMDA receptor, causes decreased Ca2+ influx that produces phosphataese
What response is there with a low frequency/uncorrelated stimulus?
A less efficient connection
