memory 3: at the level of the synapse Flashcards
what is hebbian learning
when axon a repeatedly excited axon B a proces takes place so that As efficiency of firing to B is increased.
What is the pathway which can be electrically stimulated to enduce LTP
The peforant pathway
baseline was measured.
Then multiple electric shocks were given to enduce LTP
- This produces a population response in the granule cell layer of dendate gyrus
The response a day later was larger
The response a week later way also larger
how is LTP implicated in memory
long term potentiation can be ellicited in the hippocampus easy compared to the rest of the cortex
Maximal induction of LTP does what
stops learning in the morris maze
knock out mice
knock out mice who cant do the morris maze also cant do LTP
glutamate
The brain’s most prevalent excitatory neurotransmitter, whose excessive release causes much of the brain damage resulting from cerebral ischemia
- ionotropic
what is long term potentiation (LTP)
The enduring facilitation of synaptic transmission that occurs following activation of synapse by high-intensity, high-frequency stimulation of the presynaptic neurons
NMDA receptors
Ionotropic glutamate receptors that play key roles in long term potentiation at glutaminergic synapses
- unlike normal channels they are permeable to calcium
- they are usually blocked by magnesium
- they only open when they are depolarised and glutamate binds to a receptor.
- allows calcium in which can ellicit long term changes.
what happens when glutamate binds to an NMDA receptor
it activates the receptor depolarizing the receptor, opening the ion channel allowing calcium, potassium and sodium to pass freely.
Magnesium has gone.
why is calcium important
Because calcium triggers cascades in the cell which trigger long term changes
- increases the number of synapses at the neurons
- makes proteins
calcium effects on dendritics spine
calcium enters locally and exerts its effect only at this one place
- Calcium could exert its effect very locally.
Protein synthesis
Is required for expression of LTP greater than 2 hours.
nitric oxide
a soluble gas neurotransmitter - post synaptic neurons can give information to pre- synaptic neurons with NO
What structural changes does LTP produce
more synapses after LTP
Sensitisation in DA systems
Repeated cocaine exposure facilitates LTP inductio in ventral tegmental area VTA dopamine neurons
