Learning and memory Flashcards
What types of memories are declarative?
Episodic and semantic
What was Donald Hebbs major discovery?
“Cells that wire together, fire together”
What mechanism underlies synaptic strengthening?
LTP
Who first discovered LTP
Bliss and Lomo, 1973
What did Bliss and Lomo observe?
After stimulating the neuron with a high frequency, the single stimulations that followed were causing bigger EPSPs than they were before the neuron was depolorised
What does tetanic stimulation mean?
Repeated stimulation
What animal experiment is used to test spatial memory?
Morris water maze task
At resting potential, if glutamate binds to an AMPA or a NMDA receptor what happens?
AMPA = EPSP due to sodium influx
NMDA = nothing due to Mg block
Following depolorisation/HFS, what happens to the NMDA receptor?
Mg block is removed and sodium and calcium are fluxed
What is AP5?
NMDA antagonist
What happens to rats performance on the morris water maze task , following administration of AP5?
They spend the same amount of time in all the quadrants
What happens to the cells response in rats who were injected with AP5 following a HFS?
They return to baseline instead of showing the higher EPSPs
What protein does calcium activate in the post-synaptic terminal?
CaMKII
What effect does CaMKII have on the AMPA receptors?
- It phosphorylates the existing ones, increasing their effectiveness
- Stimulates the insertion of new AMPA receptors into the membrane
What does it mean to be autocatalytic?
The first protein it phsophorylates is itself
Why can CaMKII be thought of as a molecular switch?
Because when calcium enters it, it opens up
Calcium activates nitric oxide synthase which converts to what?
Nitric oxide
Nitric oxide diffuses across the synapse and activates a second messanger system, guanylyl cyclase, whcih does what?
Produces cGMP
What does cGMP do?
Leads to an increased glutamate release from the terminal boutons
What tyoe of CREB promotes transcription?
CREB-1
The long term effects of LTP require what?
Protein synthesis
CREB-1 works more effectively when it has been phosphorylated, it is phosphorylated by kinases such as?
PKA and CaMKII
What occurs as a result of the CREB gene activation?
They make, strengthen and increase the synapses of AMPA receptors
How does long term depression occur following LFS?
AMPA receptors are dephosphorylated and removed from the membrane and low level rises in calcium activate phosphatase, which removes phosphates
Chen (1996) performed LTP and LTD on what area of the brain that was removed during the course of surgery?
The inferotemporal cortex
Tang et al, 1999 made transgenic mice expressing the NB2B receptor and they showed what?
LTP in the mice had a higher response and higher EPSP
How did this affect memory?
(after the gene had been inserted)
The rate of acquisition was not remakably different, however the T mice spent more time in the target quadrant than the controls
What factors can affect LTP?
- Enriched environment
- Age
Who found the reversal of ageing effects by enrichment?
Winocur, 1998
In the conditioned fear response, what acts as the HFS?
The actual fear stimulus
Because they are firing at the same time, the depolorisation effects from neuron A spread to neuron B. What does this mean in relation to neuron B and fear conditioning?
Overtime, activation of just neuron B will lead to a large enough EPSP to create the fear response alone, because it has been strengthened by the postsynaptic depolorisation
