Endogenous Pacemakers and S/W Cycle

Question 1

what are endogeneous pacemakers?

Answer 1

internal body clocks which regulate many of our biological ryhtms

Question 2

What is the suprachiasmatic nucleus (SCN) ?

Answer 2

a tiny bundle of nerve cells in the hypothalamus which helps maintain circadian rhythms. It is the primary endogenous pacemaker in mammals.

Question 3

1. where is the SCN postitioned?
2. why/how does it recieve information about light?

Answer 3

1. just above the optic chaism
2. nerve fibres from the eye cross at the optic chaism (where SCN lies) on the way to the visual cortex

Question 4

1. How did DeCoursey et al. (2000) demonstrate the influence of the SCN on the S/W cycle?

Answer 4

• destroyed the SCN in connections in 30 chipmunks and returned them to their natural habit and observed them for 80 days
• their sleep wake cycle were destroyed and many where killed by predators

Question 5

name 2 endogenous mechanisms

Answer 5

1. pineal gland
2. melatonin

Question 6

what is melatonin?

Answer 6

a hormone which induces sleep and is inhibted during periods of wakefullness.

Question 7

what is the SCN role in the production of melatonin?

Answer 7

it passes information (on day length) to the pineal** **gland which then increases production of melatonin during the night

Question 8

A03 a) what is one limitation of research into the SCN

Answer 8

use of animals

Question 9

A03) why is the use of animals in SCN research a limitation

Answer 9

• we cannot extrapolate (generalise) findings from animal studies to humans - humans have higher cognitive function
• ethical issues (DeCoursey) - chipmunks harmed (removal of scn connections) and put at risk when returned natural habitiat

Question 10

who used chipmunks in their study of the effective of scn on s/w cycle?

Answer 10

deCoursey (200)