Information Processing in the Nervous System

Question 1

When is the only time that ganglion cells fire APs and why?

Answer 1

Only when there’s changes in light

If the brightness stays constant there’s no response to it as the ganglion gets habituated to it

Question 2

What is convergence?

Answer 2

When a single nerve cell receives inputs from many pre-synaptic cells

Question 3

What is divergence?

Answer 3

When a single nerve cell synapses upon many other cells

Question 4

What is the difference between excitatory and inhibitory transmitters?

Answer 4

Excitatory= brings membrane potential of post-synaptic cell closer to threshold= increasing the likelihood that it will fire an AP
Inhibitory= hyperpolarisation (opposite of the excitatory synapse)

Question 5

What does a post-synaptic cell firing an AP depend on and what is this called?

Answer 5

Depends on excitation, modulation and inhibition

Called synaptic integration

Question 6

What key features does a signal from a specific pathway have?

Answer 6

• precisely localised connections
• fast synapses (ligand-gated)
• time-dependent signals
• highly selective
• info rich activity

Question 7

What is the opposite to specific pathways?

Answer 7

Modulatory pathways

Question 8

What is the pathway taken when awake?

Answer 8

Ganglion cell senses light
Transmits it to the thalamus
Which relays it to the cortex

Question 9

What is the pathway taken when asleep?

Answer 9

Modulatory signals sent to the thalamus (which usually boosts signalling from sensory cells) which produces their own bursts of activity, received by the cortex. Cortex is cut off from the retinal signal and produces its own slow wave activity