ALL STUDIES

• Evidence of localisation- Petersen et al (1988)

  • Used brain scans to demonstrate how Wernicke's area was active during a listening task
  • Broca's area was active during a reading task
  • Suggests these areas have different functions
• Evidence of localisation- Tulving et al

  • Revealed semantic and episodic memories reside in different parts of the prefrontal cortex
• Neurosurgical evidence- Dougherty et al

  • Reported on 44 people with OCD
  • All undergone a cingulotomy (lesioning the cingulate gyrus)
  • Post-surgical follow up at 32wks, 1/3 of ppts met criteria for successful response to surgery
  • 14% partial response
  • Success may suggest that symptoms/behaviours are associated with mental disorders are localised
• Case study- Phineas Gage

  • Gage experienced a metre length pole through his left cheek, passing through his left eye, and exiting his skull
  • His left frontal lobe was highly damaged
  • Gage survived but suffered from changes in temperament, decision making abilities
  • Clinical evidence that mood regulation may be localised to the frontal lobe, removal of this has caused problems
• Karl Lashley- rat study (eval point)

  • Removed areas of the cortex
  • Removed between 10-50% in rats that were learning a maze
  • No area was proven to be more important than nay other area in terms of the rats' ability to learn the maze
  • The process of learning requires every part of the cortex rather than one singular area
  • Suggests learning is too complex to be localised and requires the involvement of the whole brain
• Research into plasticity- Maguire et al, taxi driver study

  • Studied the brains of London taxi drivers
  • Found significantly more volume of grey matter in the posterior hippocampus compared to a matched control group
  • The posterior hippocampus is associated with the development of spatial and navigational skills
  • The longer drivers had been, more pronounced structural diff. (positive correlation)
  • Suggests plasticity/brain structures can be altered
• Research into plasticity- Draganski et al

  • Imaged brains of medical students
  • 3 months pre and post final exams
  • Learning-induced changes found in the posterior hippocampus and parietal cortex as a result of the exam
• Research into plasticity- Mechelli et al

  • Found a larger parietal cortex in the brains of people who were bilingual compared to monolingual controls (matched)
• Negative plasticity- Medina et al (eval point)

  • The brain's ability to rewire itself may effect behaviour
  • Prolonged drug use has been shown to result in poorer cognitive functioning and increased dementia risk
• Phantom limb syndrome- Ramachandran and Hirstein

  • 60-80% of amputees develop phantom limb syndrome
  • Thought to develop from cortical reorganisation in the somatosensory cortex as a result of limb loss
• Age and plasticity- Bezzola et al

  • Studied ppts between 40-60 years
  • 40 hours of golf training produced changes in the neural representation of movement
  • fMRI found reduced motor cortex activity in novice golfers compared to controls
  • Suggests more efficient neural representations after training
  • Neural plasticity does continue throughout the lifespan
• Support from animal studies for functional recovery- Hubel and Wiesel

  • Sewed one eye shut of a kitten
  • Analysed brains cortical responses
  • Visual cortex associated with shut eye was not idle, continued to process information from open eye (as predicted)
• Split brain study, hemispheric lateralisation- Roger Sperry

  • Studied ppts undergone a commissurotomy (where corpus callosum is severed to split the hemispheres and control epilepsy/seizures)
  • The communication line between the two halves were removed
  • Sperry studied how the two hemispheres were specialised for certain functions
• Circadian rhythm- Siffre's cave study

  • Stayed in cave in southern Alps for 2 months
  • Deprived of exposure to natural light and sound
  • Resurfaced mid september believing it was mid-august
  • Then stayed in a Texan cave for 6 months
  • In both cases his free running biological rhythm settled to 25 hours, he fell asleep and awoke on a regular schedule
• Circadian rhythm- Aschoff and Wever

  • Group of ppts spent 4 weeks in a WW2 bunker deprived of natural light
  • All but one ppt displayed a circadian rhythm between 24-25 hrs
  • The one ppt's sleep/wake cycle extended to 29hrs
  • Suggests the 'natural' sleep/wake cycle may be slightly longer than 24hours but this is entrained by exogenous zeitgebers (e.g. daylight hours)
• Circadian rhythm- Folkard et al

  • Studied a group of 12 ppts
  • Lived in a dark cave for 3 weeks
  • Ppts went to bed when clocks said 11:45pm and arose at 7:45am
  • Researchers gradually sped up the clock over the study without the ppts knowing, a 24hr day turned to 22hrs
  • Only one ppt could comfortably adjust to the new regime
  • Suggests the existence of a strong free-running circadian rhythm that cannot be easily overridden by changes in the external environment
• Circadian rhythm, Practical app, shift work- Boivin et al

  • Night workers engaged in shift work experience a period of reduced concentration around 6am
  • A circadian trough meaning mistakes and accidents are more likely
  • This may implicate economically into how to manage worker productivity due to circadian rhythm research and better understanding desynchronisation can cause
• Circadian rhythm- poor health, Knutsson

  • Relationship between shift work and poor health
  • Shift workers are 3x more likely to develop heart disease
  • This may be due to stress of adjusting to different sleep/wake patterns and lack of poor quality sleep during the day
• Circadian rhythm- practical app, drug treatments, Baraldo 2008

  • There are certain peak times during day/night when drugs are most effective
  • Led to developments of guidelines to do with timing of drug dosing (e.g anticancer, cardiovascular, respiratory, anti epileptic drugs)
  • This has a positive effect on pharmacokinetics (action of drugs and absorption rates) helping those with serious conditions on how to use their circadian rhythms to optimise bodily processes and drug intake
• Infradian rhythms- menstrual cycle support Stern and Mcclintock

  • Studied 29 women with irregular periods
  • Samples of pheromones were gathered from 9 women at different stages of their menstrual cycles via a cotton pad under their armpit (worn for 8 hours).
  • Pads were treated with alcohol, frozen and rubbed onto the upper lip of the other 20 ppts.
  • On day 1, pads from the start of the menstrual cycle were applied to all 20 women, day 2 they were given a pad from the second day of the cycle etc
• Stern and McClintock findings

  • 68% of women experienced changes to their menstrual cycle which brough them close to the cycle of their ‘odour donor’
  • Therefore suggests female pheromones can (an exogenous factor) can influence our menstrual cycle (endogenous system)
• Ultraradian rhythm, sleep- research support Dement and Kleitman

  • Monitored sleep patterns of 9 adults in a sleep lab.
  • Activity recorded on an EEG. Researchers controlled for the effects of caffeine and alcohol.
  • REM activity during sleep was highly correlated with the experience of dreaming
  • brain activity varied according to how vivid dreams were and ppts woken during dreaming reported very accurate recall of their dreams
  • Evidence supports the idea of distinct stages in sleep and REM sleep is an important component of the ultradian sleep cycle
• Infradian rhythm, SAD- practical app Eastman et al

  • Most effective treatments for SAD is phototherapy
  • Relieves symptoms up to 60% of sufferers
  • However placebo effect produced relief in 30% of ppts
  • May cast doubt on the chemical influence (on melatonin) of phototherapy (exogenous influence)
• Endogenous pacemakers and the sleep/wake cycle- Animal study De Coursey et al

  • destroyed the SCN connections in the brains of 30 chipmunks
  • returned to their natural habitat, observed for 80 days.
  • The sleep-wake cycle of the chipmunks disappeared
  • by the end of the study a significant proportion of them had been killed by predators (presumably because they were awake and vulnerable to attack when they should have been asleep)
  • Suggests Circadian rhythms are key in survival and disruptions increase vulnerability especially to predators
• Animal studies and the SCN- Ralph et al

  • Bred ‘mutant’ hamsters with a 20-hour sleep-wake cycle
  • When SCN cells from the foetal tissue of the mutant hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20 hours
  • Suggests SCN cells determine the rhythm’s timing.
  • Both of these studies emphasise the role of the SCN in establishing and maintaining the circadian sleep/wake cycle and aligning behaviour with environmental demands.
• Exogenous zeitgeber, light- research evidence Campbell and Murphy

  • 15 ppts, woken at various times and a light pad was shone on the back of their knees
  • demonstrates that light may be detected by skin receptor sites on the body even when the same information is not received by the eyes.
  • Caused a deviation in their sleep/wake cycle from up to 3 hours.
  • Suggests light is a powerful exogenous zeitgeber that doesn’t need to rely on the eyes to exert its influence on the brain
• EZ Light- Burgess et al

  • Volunteers participated in – continuous bright light, intermittent bright light or dim light
  • each of which shifted their sleep-wake cycle one hour a day over a period of three days.
  • Continuous- 2.1 hr shift
  • Intermittent bright light: 1.5 hr shift
  • Dim light: 0.6 hr shift
• Burgess et al findings 2

  • Ppts in the first treatment group felt sleepier two hours earlier in the evening, and woke 2 hours earlier in the morning (i.e. closer to the local time conditions they would find after an east-west flight.)
  • Suggests exposure to bright light prior to an east-west flight decreased the time needed to readjust to local time on arrival.
  • Light has a large impact on circadian rhythms as suggested and acts as an external cue to synchronise biological rhythms to environmental changes
• Research evidence for other influences on sleep/wake aside from SCN- Damiola et al

  • Changed feeding patterns in mice
  • Circadian rhythm of cells in liver changed up to 12 hours
  • SCN rhythm unaffected
  • Suggests there are other complex influences on sleep/wake cycle, these peripheral clocks can act independently regardless of SCN influence
• Exogenous zeitgebers may be overstated- Miles et al.

  • Man blind from birth had a circadian rhythm of 24.9 hrs
  • Despite exposure to social cues, sleep/wake cycle could not be adjusted
  • He had to take sedatives at night and stimulants in the morning to keep pace with 24hr clock
  • Suggests there are times where exogenous zeitgebers have little influence over our internal rhythm, challenges previous suggestions