3.5 Spatial and temporal summation

Question 1

What is spatial summation

Answer 1

Two or more presynaptic neurone release neurotransmitter at the same time onto the same postsynaptic neurone.

Question 2

What can cause there to be no action potential in spatial summation?

Answer 2

If some presynaptic neurones release an inhibitory neurotransmitter at the same time onto the same postsynaptic neurone.

Question 3

What is temporal summation, and why does it make an action potential more likely?

Answer 3

Two or more nerve impulses arrive in quick succession from the same presynaptic neurone.

Question 4

Why do impulses have to follow each other very quickly in temporal summation?

Answer 4

Otherwise the neurotransmitter will be removed from the cleft before it’s reached a level high enough to trigger an action potential.