L6 - The Plastic Synapse Flashcards
What is the structure of the synapse?
pre-synaptic terminal
- machinery for making and concentrating transmitter in vesicles
- machinery for allow rapid fusion of vesicles
synaptic cleft
- essentially CSF
Postsynaptic membrane
- High concentration of membrane bound proteins that sense chemical transmission
Describe synaptic transmission
Action potential invades the pre-synaptic terminal
The rseulting depolarisation open Ca2+ channels
Ca2+ binds to a sensor protein
transmitter filled vesicles are drawn to the pre-synaptic membrane where they fuse
Transmitter spills across the narrow cleft
transmitter bind post-synaptic receptors that open allowing ions to flow
What are the two major neurotransmitters in the CNS
- Excitatory = Glutamate
2. inhibitory: GABA
What are the postsynaptic receptors for GABA?
GABA(a) receptors = Cl-
What are the postsynaptic receptors for Glutamate?
AMPA receptors = NA+ (the workhorse)
NMDA = Ca+ (the communicator)
What 3 synaptic properties define synaptic strength?
Number of synapses
Probability of release
Quantal size
What properties do you need from synaptic plasticity if this is where memories are formed?
specificity
co-operativity - cells that wire together fire together)
Longevity (can be measured for years in vivo
What is LTP?
long term potentiation
Trains of stimulation resulted in a long-lasting increase in synaptic strength. these were specific, co-operative and long-lasting
which receptor and neurotransmitter is responsible for LTP?
postsynaptic Ca2+ through NMDA receptor
How does the NDMA receptor act as a coincidence detector?
what goes wrong when trhe ability to remember is lost?
Synapses lose their ability to be plastic
- AD
- Down syndrome
- Age
Why has there been show progress in understanding dementia and other neuro disorders?
Although synapses are critical to the formation of memory we are a long way from fully understanding how memories are formed
therefore it is difficult to fix
What are the problems with studying the brain?
encased in a hard shell
the electric signal (AP) occurs very quickly
the brain is a series of connected neuronal networks – 100 billion neurons connected in trillions of possible ways
What are the new ways to look at the brain?
MRI
Dense Arrays of electrodes measuring electrical activity - can record many places but still only clusters of neurons
