Biopsychology

Question 1

Outline and evaluate the effect of endogenous pacemakers and exogenous zeitgebers on the sleep wake cycle. (16)

Answer 1

AO1:
- Enodgenous pacemakers: internal body clocks, regulate bio rhythms, such as influence of SCN on sleep/wake/cycle.
- Exogenous zeitgebers: external factors that affect/entrain bio rhythms.
- Sleep wake cycle: daily cycle of bio activity based on 24 hour period.
- SCN recieves info about light, this even happens when eyes are closed, enables bio clock to adjust to changing patterns of daylight when asleep.
- EZ: light, can reset body’s EP and maintains sleep/wake cycle.

AO3:
Strength = support for effect of light.
- Siffre’s cave study.
- Cave, no natural light, entered in mid July came out in mid September but thought it was mid August.
- Light helps maintain circadian rhythms.

Strength = research support for effect of SCN on sleep/wake cycle.
- Decoursey et al: destoyed SCN cells in 30 chipmunks, sleep/wake cycle disappeared.
- SCN maintains our sleep/wake cycle.

Limitation = SCN research obscures other body clocks.
- Other organs have body clocks.
- Partly influenced by the SCN.
- There are other complex influences on the sleep/wake cycle.

Question 2

Outline and evaluate two or more ways of studying the brain. (16)

Answer 2

AO1:
- Functional magnetic resonance imaging (FMRI): measures brain activity while person does a task, detects radio waves from changing magnetic fields, detects regions of the brain that are rich in oxygen and therefore active.
- Electroencephalogram (EEG): record of tiny electrical impulses produced by brain’s activity, measures wave patterns, can diagnose certain conditions of the brain.

AO3:
FMRI:
+ Doesn’t rely on radiation, is used correctlly it is virtually risk-free, non-invasive and straightforward.
High sptail resoltuion, provides clear picture of how brain activity is localised.
- Expensive. Poor temporal resolution because there is around a 5 second time lag behind the image on screen and initial firing of neuronal activity.

EEG:
+ Useful in studying stages of sleep and in diagnosing conditions such as epilepsy as it can detect random bursts of activity in the brain that can be easily detected.
- Generalised nature of the information recieved. Can’t pinpoint exact source of neural activity.

Question 3

Outline and evaluate split brain research. (8)

Answer 3

AO1:
- Conducted by Sperry.
- Done to reduce epileptic fits by cutting connections between the 2 hemispheres. (cut the corpus callosum).
- 11 split brain patients were shown images to the RVF and LVF. They could explain what they saw when it was shown to their RVF, but not their LVF as the LH is responsible for language so they didn’t have the words to explain what they had seen.
- A ‘normal’ brain can communicate across the 2 hemispheres, a split brain can’t.

AO3:
Strength = Supporting research.
- Gazzaniga: said that split-brain patients perform better on some tasks. eg = can identify the odd one out easier and faster.
- In a normal brain the LH’s cognitive abilities are ‘watered down’ by the inferior RH.
- Supports Sperry’s earlier findings.

Limitation = Generalisation issues.
- They were compared to a neurotypical control group without epilepsy.
- Differences between results may have been a result of epilepsy and not split brain.