Intro to CNS

Question 1

What is the brain?

Answer 1

• Input-output device
• Sensory info is processed and responded to
• 100 billion neurons, 100 billion glia, trillions of synapses

Question 2

What is Glutamate?

Answer 2

• Main excitatory transmitter

Question 3

What is GABA?

Answer 3

• Main inhibitory transmitter

Question 4

What are regional microcircuits?

Answer 4

• Straightforward circuit focussed on Purkinje cells
• 2 excitatory inputs:
• ~175,000 parallel fibres
• 1 climbing fibre
• Inhibitory interneurones feed forwards and backwards (Golgi, Basket and Stellate cells)
• Strength of connections can be modulated–Synaptic plasticity

Question 5

What is regional specialisation?

Answer 5

• Broad brush association of behavioural phenomena with substructures
• Amygdala–FEAR
• Cerebellum–Motor co-ordination
• Prefrontal cortex–Executive control

Question 6

What are Neuromodulatory transmitters?

Answer 6

• Long-distance projections that overlay synaptic network
• Volume transmission mechanism
• Distributed inputs that modulate microcircuits

Question 7

Give some examples of modulatory transmitters?

Answer 7

• Dopamine
• 5-HT
• Noradrenaline
• Acetylcholine
• Histamine
  ETC

Question 8

What are consequences of neuromodulation?

Answer 8

• Inc or Dec excitatability
• Inc or Dec synaptic release probability
• After sensitivity to synaptic plasticity –Metaplasticity
• Modulate gene expression
• Shape dev, connectivity and computational properties or neuronal networks

Question 9

Explain complexity of the brain/NTs

Answer 9

• All neuromodulators play multiple roles
• Reflects widespread inf
• Extensive crosstalk and interconnectivity
• Makes targeted interventions difficult

Question 10

What is selectivity?

Answer 10

Receptor subtypes and reuptake transporters selectivtly expressed
* Coupled to different 2nd messenger signalling pathways
* Diff effects on neuronal function
* Expressed on dif classes of neurons
* Density varies in dif brain regions

Question 11

What is Dopamine?

Answer 11

• Neuronal somata collected into 2 main brainstem regions
  1. Ventral tegmental area
  2. Substantia nigra
• Also in Hypothalamus
• Project to multiple brain regions through 4 main pathways
  1. Mesolimbic
  2. Mesocortical
  3. Nigrostriatal
  4. Tuberoinfundibular

Question 12

Decribe the dopamine pathways

Answer 12

Question 13

What are the roles of dopamine?

Answer 13

1. Reward
2. Motivation
3. Pleasure-seeking
4. Salience
5. Movt
6. Attention
7. Arousal
8. etc

Question 14

What is 5-HT?

Answer 14

• Brainstem nuclei
  1. Raphe nuclei
• Widespread projections throughout brain and spinal cord
• Serotonergic pathway

Question 15

What are the roles of 5-HT?

Answer 15

• Mood regulation
• Cognition/perception
• Feeding behaviour
• Sexual behaviour
• Aggression
• Sleep regulation
• Temp regulation
• etc

Question 16

What are pharmocological challenges for (brain?) management?

Answer 16

• Selective therapeutic effect v.diff to achieve
• Enormous pot for on-target and off-target side effects
• Extensive crosstalk
• Pharmacokinetics and BBB
• Approved drugs often broad spectrum