Synaptic Efficacy

Question 1

Define synaptic efficacy (1)

Answer 1

The magnitude of post-synaptic response to a given amount of pre-synaptic stimulation.

Question 2

Define synaptic plasticity (2)

Answer 2

A prolonged change in synaptic efficacy. Results in either a change in circuit function or behavioural plasticity.

Question 3

Name 2 forms of short-term synaptic plasticity.

Answer 3

Synaptic facilitation and synaptic depression.

Question 4

Define a paired-pulse facilitation (2)

Answer 4

When 2 pre-synaptic stimuli occur a few milliseconds apart. Paired pulse facilitation occurs if the post-synaptic response to this second stimuli is greater than the response to the first.

Question 5

Describe Synaptic Facilitation (4)

Answer 5

• A rapid increase in synaptic strength
• Form of ShT plasticity
• Arises due to pre-synaptic modifications that increases lvl of NT release
• Occurs when 2 or more APs invade the pre-synaptic terminal within a few 100 ms

Question 6

Describe the Residual Calcium Hypothesis (2)

Answer 6

• Calcium ions enter the pre-syn terminal at depolarisation.
• If the calcium lvls do not have time to return to their resting lvl / baseline conc. before the 2nd AP, will result in a higher calcium concentration.

Question 7

Describe Synaptic Depression (3)

Answer 7

• A decrease in synaptic efficacy
• For of ShT plasticity
• Occurs when repeated stimulation causes NT release to decline

Question 8

Describe the timeframe of facilitation.

Answer 8

50-300 millisecs

Question 9

Describe the timeframe of post-tetanic potentiation.

Answer 9

10s of seconds - 1 min

Question 10

Describe post-tetanic potentiation (3)

Answer 10

• A form of ShT synaptic plasticity
• Increases amount of NT released from pre-syn terminal by enhancing ability of incoming calcium to trigger vesicle release
• Elicited by repeated synaptic activity