11. Glutamate to LTP Flashcards
What is LTP? (LTP B&B)
- Long term potentiation
- A phenomena that explains memory at the synaptic level, through synaptic strengthening
Where is declarative memory stored and what is it involved in? (LTP B&B)
- Medial temporal lobe
- Facts and major life events
What two concepts are associated with non-declarative memory? (LTP B&B)
- Procedural memory
- Classical conditioning
Where is procedural memories stored and what is it involved in? (LTP B&B)
- Striatum
- Skills and habits
Where is classical conditioning memories and what is it involved in? (LTP B&B)
- Amygdala
- Emotional responses
What did Hebb (1949) suggest and what did he mean by it? (LTP B&B)
- ‘Cells that fire together, wire together’
- Strengthening and weakening the synaptic connections in the brain provides a platform for learning and memories
What is the main part of the brain involved in LTP? (LTP B&B)
Hippocampus
What are the three types of LTP? (LTP B&B)
- Temporal LTP
- Associative LTP
- Specific LTP
How is LTP induced temporally? (LTP B&B)
Summation of inputs reaches a stimulation threshold that will induce LTP
How is LTP induced associatively? (LTP B&B)
Simultaneous stimulation of a strong and weak pathway will induce LTP at both pathways
How is LTP induced specifically? (LTP B&B)
LTP at any one synapse is not propagated to adjacent synapses
How is the Morris water maze performed? (LTP B&B)
- Small platform slightly below water level
- Rat eventually finds the platform and learns the location
- Each time they are put back in the water they swim to the learnt spot of the platform
What happens if the platform is removed in the Morris water maze? (LTP B&B)
The rat spends the majority of time swimming in the area where the platform was before
What happens when the rats hippocampus is removed and then they perform the Morris water maze? (LTP B&B)
- No spacial memory created
- Memory of the platform is non existent
What are the parameters for the Morris water maze? (LTP B&B)
- Escape latency (training)
- Time in the quadrant (probe trial)
- Annulus crossing (probe trial)
How can memory in the Morris water maze and LTP be impaired artificially? (LTP B&B)
NMDA antagonist (AP5)
What is the process of glutamate being released onto an inactive cell? (LTP B&B)
- AMPA receptors activated to create EPSP
- NMDA receptor blocked by Mg2+
- Depolarisation from AMPA activation is not enough to expel Mg2+
What is the process of glutamate being released onto an active cell? (LTP B&B)
- AMPA receptor activated
- Mg2+ blocks NMDA receptor
- Na+ moves through AMPA and NMDA channels
- Ca2+ through NMDA channels
What does Ca2+ entry through NMDA receptors lead to? (LTP B&B)
Activation of calcium calmodulin dependent protein kinase II (CaMkII)
What does the CaMkII modular switch do? (LTP B&B)
Sustains activity after repolarisation
What is the process of the CaMkII modular switch? (LTP B&B)
- Ca2+ enters through NDMA receptors
- CaMkII activated
- CaMkII is autocatalytic
- Phosphorylation leads to Ca2+ not required
- Phosphorylation is sustained after depolarisation stimulus is removed
- Modular switch maintains increased excitation in the neuron
What is meant by CaMkII having autocatalytic activity? (LTP B&B)
It becomes phosphorylated (remains open/active)
What is the process of LTP through retrograde transmitters? (LTP B&B)
- Ca2+ through NMDA channels
- Nitric oxidise synthesis activated
- Nitric oxidise diffuses from site of production
- Activates guanylyl cyclase (presynaptic)
- Guanylyl cyclase produces second messenger (CGMP)
- Signgnalling transduction cascade leads to increased glutamate
How is early phase LTP explained? (LTP B&B)
Actions of Ca2+ through NMDA receptors and enhancement of AMPA receptor efficiency presynaptically
How is late phase LTP explained? (LTP B&B)
Ca2+ activates signal transduction cascades which activates protein synthesis and signals to the cell body
What is the opposite of LTP? (LTP B&B)
Long term depression
