Neuroscience

Question 1

Describe the functional divisions of nervous system

Answer 1

Afferent: sensory information from receptors to CNS

Efferent: Motor command to muscles

Question 2

Describe the different parts of nerons

Answer 2

Cell body: central part where most protein synthesis occurs

Nucleus: Contains DNA/RNA

Dendrite: Carries electrical signal towards cell body

Axon: Carries electrical signal away from cell body

Axon terminal: neurons connect to other neurons

Myelin sheet: fat around axon (facilitates electrical transmission)

Node of Ranvier: gaps in myelin sheet

Question 3

What is neuronal excitability

Answer 3

Likelihood that a neuron will fire (chemical changes in or outside cell can change membrane potential (electrical voltage) –> action potential (fire of electrical signal)

Question 4

What is the resting potential and how does it change?

Answer 4

= voltage when neuron is not firing (polarised)

Changes in sodium and potassium change potential –> action potential

Question 5

What are the 2 stages of AP and what follows?

Answer 5

Resting state (-70mV): Na+ gates resting, k+ closed

1) Depolarising phase (Na+ gates open more) –> Action potential (40mV)
2) Repolarising phase (K+ opens, Na+ closes) –> refractory periode (no new AP)

Question 6

What are glial cells?

Answer 6

(eg astrocytes): smaller then neurons, insulate and support neurons (about 50% of volume in CNS)

Question 7

What is sleep’s effect on memory?

Answer 7

• non-REM sleep –> greater performance in explicit memory

- REM –> greater implicit memory

Question 8

What happens when we sleep?

Answer 8

• recurring cycle of 90-120 mins: -Non-REM sleep (4 stages of 5-20 min) + REM sleep

Question 9

What are the 4 stages of nREM sleep?

Answer 9

1) light sleep - muscle activity slows
2) (45-55%) Breathing and heart rate slows
3) Deep sleep starts - slow delta waves
4) (12-15%) Very deep sleep - limited muscle activity

Question 10

What happens in REM sleep?

Answer 10

Begins 70-90 mins in: 20-25% of all sleep: 3-5 phases a night

Where most dreams occur - we are not conscious, but brain is very active

Finishes cycle - after it all begins again

Question 11

What is the pathophysiology of insomnia?

Answer 11

• Hyperarousal: Basal metabolism, heart rate etc is higher in insomniacs. Increasing arousal induce insomnia - however, lack of sleep does not cause arousal - causality?
• Elevated HPA (hypothalamic-pituitary-adrenal axis) levels associated with insomnia

Question 12

What are the bases of alzheimers?

Answer 12

= Cortical demantia (mostly cognitive)

Neurophysiological:

• neurofibrillary (twisted pair of helical filaments within neuron)
• amyloid plaques

neuropschology:
- loss of grey matter, cortical thinning, increased ventricle size (result of plaques and tangles) - loss directly related to memory loss

Question 13

What are the neurophysiological bases of parkinsons?

Answer 13

= Sub cortical dementia (mostly motor symptoms)

Majority of symptoms caused by death of dopamine secreting neurons in the substantia nigra
Also basal ganglia lesions can produce PD like symptoms

Question 14

What is Mirror neurons?

Answer 14

In brain area F5 (Broca –> origins of language?): Think monkeys and peanuts:

Fires when same GOAL (not movement) is achieved (eg getting peanut using normal or reversed pliers) –> Transitive only (movements directed toward object)

Question 15

What is the ‘mu’ rythm?

Answer 15

8-13Hz: change in power at a specific frequency: decrease in power –> increase in brain activity (think firing at different vs same time)

–> Mirror neurons may code relevance or importance of action