L2: Neurons and Neuronal Networks: Synaptic Transmission and Inhibition

Question 1

what is reversal potential?

Answer 1

membrane potential at which direction of ionic current reverses

• no net flow of ions from one side of the membrane to the other

Question 2

why is lateral inhibition important?

Answer 2

• without it there would be activation in multiple neurones and can’t differentiate specificity of sensory stimuli e.g. touch
• and so can’t move away from harmful stimuli as fast

Question 3

what are the two types of synaptic modulation?

Answer 3

1. presynaptic inhibiton
2. postsynaptic inhibition

Question 4

what occurs in presynaptic inhibiton?

Answer 4

1. an excitatory neuron fires
2. an AP is generated
3. an inhibitory neuron fires blocking NT release at 1 synapse
4. postsynaptic response elicited in 2 of 3 targets

Question 5

what occurs in postsynaptic inhibition?

Answer 5

1. an excitatory and an inhibitory neuron fire (they will cancel each other out so…)
2. an excitatory and inhibitory postsynaptic potentials result in a below threshold graded potential
3. no AP is generated
4. no response elicited in any target

Question 6

what are the two differences between presynaptic and postsynaptic inhibition?

Answer 6

presynaptic inhibition:

• more specific control
• precise inhibition of specific synapses

postsynaptic inhibition

• general inhibition
• all synapses inhibited equally