Modifying synaptic function

Question 1

The chemical synapse

Steps in synaptic transmission (7)

Answer 1

Steps in synaptic transmission:

production and packaging of neurotransmitter
depolarisation and calcium entry
calcium triggers exocytosis
neurotransmitter binds to receptors
receptors activate and produce postsynaptic effects
neurotransmitter is removed from cleft and hence receptors
receptor action terminates

Question 2

Learning, memory and repair – synaptic plasticity

what does learning and memory involve?
repair involves?

Answer 2

Learning/memory involve the synapse/circuits changing

repair involve re-wiring so the surviving cells make new circuits to restore function

Question 3

The best understood mechanism of plasticity is
Long-Term Potentiation (LTP)

hows does LTP affect fast excitatory synapses (2)

how does rehabilitation work?

Answer 3

LTP affects fast, excitatory synapses in a way that:
strengthens effective synapses
weakens useless synapses
in this way, creates a more effective neural circuit

rehabilitation -> strengthen pathways that had been inactive therefore produce new circuits

Question 4

Long-Term Potentiation (LTP)

what happens if synapses activitates on its own?

if group activate? repeatedl;y?
what will this group recieve? effect?

lone synapse?

what can generate second messengers for this?

Answer 4

If a synapse activates on its own, it will be weak
If this happens persistently then the synapse isn’t doing anything useful

If a group of synapses activate together, they will produce a large depolarisation and maybe an AP
If this happens persistently, it suggests that they are co-operating as part of a circuit

The group of synapses will receive support from the postsynaptic cell, and will strengthen (potentiate)
The lone synapse will not receive support, and will weaken

Activation of some metabotropic receptors generates second messengers that enhance LTP