Neural Networks

Question 1

Answer 1

Question 2

What are the 2 patterns of cellular connections in networks of neurons?

Answer 2

DIVERGENT

(one neuron regulates multiple targets)

CONVERGENT

(one neuron is regulated by multiple targets)

Question 3

What response do ligand-gated channels produce?

What do GPCR produce?

Answer 3

FAST & LOCALISED responses

SLOW & MORE WIDESPREAD

Question 4

What are the 2 excitatory neurotransmitters?

What type of ionic flux results?

What effect do they produce?

Answer 4

Glutamate

ACh

Ionic flux = CATION

Depolarisation, Vm +

Question 5

What are the 2 inhibitory neurotransmitters?

What type of ionic flux results?

What effect do they produce?

Answer 5

GABA

Glycine

Ionic flux = ANION

Hyperpolarisation, Vm-

Question 6

What are Inhibitory interneurons?

Answer 6

Provide local (-) control of activity

-important for network functions (i.e. enhancing signals & switching between output pathways)

Question 7

What are the 2 examples of inhibitory interneurons?

Answer 7

1. Focusing the source of a signal (using an “inhibitory surround” mechanism)!
2. Using INHIBITORY INTERNEURONS to create a DECISION POINT in a network

NOTE* –> PACEMAKER cells are spontaneously active

Question 8

How do inhibitory interneurons ‘focus the source of a signal’?

Answer 8

USING AN INHIBITORY SURROUND MECHANISM!

(Each excitatory field has a ZONE OF INHIBITION around it, intended to focus the signal)

Question 9

Focusing the source of a signal CONT.

Answer 9

The nervous system is regulated by increases and decreases in the ongoing (basal) firing rate

Question 10

Answer 10

RHS: Inhibitory effects that would be generated by surrounding zones are all OFF, thus leaving centre circle bright

LHS: The central point of focus (circle) is inhibited by the activated surrounding fiels, & looks darker!

Question 11

How do inhibitory interneurons ‘create a decision point in a network’?

Answer 11