Biopsych stress

• Sperry Procedure


  Studied 11 epileptic people who had undergone a split-brain procedure. Images were projected separately to the participants RVF and LVF. A 'normal' brain would share information between the two hemispheres. A split-brain patient cannot do that.
• Sperry Findings


  When a picture was shown to the RVF, they could describe what was seen but they couldn't see anything when the image was shown to the LVF. When an image was shown to the LVF they couldn't give verbal labels but they could select a matching object to the image. When a picture was shown to the LVF there was an emotional reaction (e.g. giggling) but the participants usually reported seeing nothing or just a flash of light.
• Lateralisation


  There are two sides to the brain. The left hemisphere is the analyser and the right hemisphere is the synthesiser. The two main language centres are in the left hemisphere. Motor, vision and somatosensory areas appear in both hemispheres. LVF = RH and RVF = LH.
• Lateralisation Evaluation


  + Lateralisation in connected brain. Even in the connected brain the two hemispheres process information differently. Fink used PET scans to identify active brain areas during a visual processing task.

  (-) One brain. LH as analyser and RH as synthesiser may be wrong. There may be different functions in the LH and RH. Some research suggests people have no dominant brain side. Left brained or right brained people could not be real.
• Plasticity


  The brain changes rapidly during infancy. Synaptic pruning enables lifelong plasticity where new neural connections are formed. Maguire et al. studied London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group. There is a positive correlation between the time at the job and the volume of grey matter.
• Negative Plasticity


  May have negative behavioural consequences
• Negative Plasticity


  • Phantom limb syndrome (60 to 80% of amputees experience this)
• Negative plasticity shows that the brain's ability to adapt to damage is not always beneficial
• Age and Plasticity


  Brain plasticity may be a life long ability. In general, plasticity reduces with age.
• Plasticity in older adults

  • A research study on novice golfers aged 40 to 60 showed that after 40 hours of golf training there were changes in the neural representation of movement
• Using fMRI observed increased motor cortex activity in novice golfers which shows neural plasticity can continue through lifespan
• Functional Recovery


  After damage to the brain the unaffected areas can adapt and compensate for the damaged areas. The brain is able to rewire by forming new synaptic connections close to the area of damage. Axonal sprouting -> a growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways.
• Functional Recovery Evaluation


  + Real-World Application. There is contribution to the field of neurorehabilitation and axonal growth encourages new therapies.

  (-) Cognitive Reserve. Level of education may influence recover rates. Schneifer et al. = more time in education and brain injury = increased chance of disability free recovery. 40% of DFR had 16+ years of education and 10% of DFR had less than 12 years of education.
• fMRI


  Detects changes in blood oxygen. When a brain area is more active it consumes more oxygen and blood flow is directed to the active area. It produces 3D images showing which parts of the brain are involved in a particular mental process. Helps to understand localisation.
• fMRI Evaluation


  +doesn't rely on radiation

  +virtually risk-free and non-invasive

  +produces high spatial resolution images

  (-) expensive

  (-) poor temporal resolution because there is a 5 second time lag between brain activity and what can be seen on screen
• EEGs


  Measures electrical activity within the brain via electrodes (skull cap). Unusual arrhythmic patterns may indicate neurological abnormalities (epilepsy, tumours or some sleep disorders).
• EEGs AO3


  +useful in studying stages of sleep

  +diagnosis of conditions e.g. epilepsy

  +high temporal resolution

  (-)not useful for pinpointing the exact source of neural activity
• ERPs 


  Brain waves triggered by particular events. Isolates EEG neural responses.
• ERPs AO3


  +high temporal resolution

  (-)lack of standardisation

  (-)can't always completely remove extraneous material
• Post-Mortems


  Analysis of the brain after death. Usually involves comparison with a neurotypical brain.
• Post-Mortem AO3


  +Broca and Wernicke relied on post-mortem studies for their research.

  +Foundation for early understanding of key processes in the brain.

  (-)Ethical issues of consent
• Biological Rhythms


  Body's internal biological clocks = endogenous pacemakers. External changes in the environment = exogenous zeitgebers.

  • Ultradian -> rhythms occur many times during the day.
  • Infradian -> take longer than a day to complete.
  • Circadian -> last for around 24 hours.
• Circadian - Sleep/Wake Cycle


  Daylight is an exogenous zeitgeber. The SCN is an endogenous pacemaker. SCN provides information from the eyes about light. Light can reset the SCN.
• Circadian - Siffre


  Studied effects of his own biological rhythms. Deprived himself of natural light and sound but had a lamp. Came out of the cave after 2 months in mid-September but thought it was mid-August.
• Circadian - Evaluation


  +provides an understanding of consequences of disruption (desynchronisation).

  • night workers experience a period of reduced concentration at around 6am where accidents are more likely.
  • There was a link found between shift work and poor health.
  • Research into the sleep/wake cycle may have real-world economic implications in terms of how to manage worker productivity.
• Circadian - Evaluation


  +used to improve medical treatments

  • aspirin reduces heart attacks
  • heart attack most likely in early morning
  • timing of taking aspirin matters
  • can help increase effectiveness of drug treatments
• Circadian - Evaluation


  (-)generalisations are difficult to make

  • sleep/wake cycles vary widely from person to person.
  • difficult to use the research data to discuss anything more than averages.
• Infradian


  menstrual cycle

  • approx 28 days
  • exogenous zeitgebers - other women's cycles
  • samples of pheromones from armpits rubbed on the upper lips of other participants
  • 68% of women experienced changes to their cycle
• Infradian Evaluation


  +menstrual synchrony and natural selection

  • for distant ancestors it may have been advantageous to menstruate together and get pregnant at the same time.
  • allows babies with no mothers access to breast milk, improving chances of survival.
  • (-) methodological limitations
  • confounding variables for the menstrual cycle (stress levels, diet changes and exercise)
  • suggests that menstrual synchrony studies are flawed
• Ultradian


  Stages of Sleep

  • approx 90 minutes
  • EEG monitoring
  • Stages 1 and 2 -> light sleep and easily awaken.
  • Stages 3 and 4 -> deep sleep and slow wave sleep. difficult to awake.
  • Stage 5 -> REM. dreaming.
• Ultradian Evaluation


  (-)significant variation between people

  • large differences between participants in terms of sleep stage duration
  • difficult to describe 'normal sleep' in a meaningful way.
  • + improved understanding of age-related changes in sleep.
  • SWS reduces with age
  • old people have reduced alertness
• Endogenous Pacemakers and Sleep/Wake Cycle

  SCN - lies about the optic chiasm

  • Requires info about light and continues even when our eyes are closed which enables the biological clock to adjust to changing patterns of daylight whilst we are asleep.

  Animal Studies + SCN

  • Destroyed SCN connections in 30 chipmunks and most had been killed by predators as they were supposed to be asleep so more vulnerable to attack.

  Pineal Gland + Melatonin

  • Pineal gland increases production of melatonin which induces sleep.
• EP Evaluation


  (-)May obscure other body clocks

  Numerous circadian rhythms in the body. Influenced by actions of SCN but also act independently. Suggests other complex influences on the sleep/wake cycle.

  (-)Cannot be studied in isolation

  Total isolation studies (Siffre) are rare. Siffre had artificial light which could have reset his biological clock. The more researchers attempt to isolate the influence the influence of internal pacemakers, the lower the validity of the research.
• Exogenous Zeitgebers and Sleep/Wake Cycle

  LIGHT

  • key zeitgeber in humans
  • light may be detected by receptors on the skin when info not received by eyes.
  • 15 participants woken at various times and light pad shone on the back of their knees.
  • the researchers produced a deviation in the participants usual sleep/wake cycle.

  SOCIAL CUES

  • newborn babies have random sleep cycles until about 16 weeks when schedules settle in.
  • research on jet lag suggests that adapting to local times for eating and sleeping is an effective way of entraining circadian rhythms and beating jet lag
• EZ Evaluation


  (-)EZ don't have same effect in all environments.

  • suggests sleep/wake cycle is primarily controlled by EPs that can override environmental changes in light.

  (-)Evidence challenges the role of EZs.

  • blind man had abnormal circadian rhythms of 24.9 hours despite exposure to social cues.
  • suggests social cues alone are not effective in resetting the biological rhythm.