Essay plans

• Exogenous zeitgebers


  External changes to the environment
• Endogenous pacemakers


  Internal body clocks
• Suprachiasmatic nucleus (SCN)


  • Affects the sleep/wake cycle
• Light


  • Has an effect on sleep/wake cycle
• Destroying SCN cells in chipmunks


  Results in their sleep/wake cycle disappearing
• Mutant hamsters with 20-hour cycles


  When their SCN cells were transplanted into normal hamsters, their cycles altered
• There are many organs which have body clocks known as peripheral oscillators which have an effect on the sleep/wake cycle
• Research is limited by always thinking of endogenous pacemakers and exogenous zeitgebers as separate. Perhaps their effects should be thought of as combined and studied holistically
• Functional magnetic resonance imaging (FMRI)

  Measures brain activity by detecting changes in blood oxygenation
• Electroencephalogram (EEG)


  Records changes in electrical activity of the brain by using electrodes attached to the scalp
• FMRI


  • Non-invasive, high spatial resolution, able to image brain in action
• EEG


  • Used for clinical diagnosis, high temporal resolution (single millisecond), non-invasive
• Localisation of function


  Theory that different areas of the brain are responsible for different specific behaviours or activities
• Broca's area and Wernicke's area


  • Located only in the left hemisphere
• The opposing theory is the holistic theory which instead states that all parts of the brain are involved and work together in processing thoughts and actions
• Plasticity provides an argument against localisation, as equipotentiality takes place in patients that have been subject to brain injury, where the brain reorganises itself after damage to recover lost function in a different part of the brain
• Fight or flight response (FFR)


  A collection of quick physical reactions to situations which are stressful
• Circadian rhythms


  A type of biological rhythm subject to a 24-hr cycle which regulates a number of body processes