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BIOPSYCHOLOGY (Year 2) (biological rhythms (infradian (cycle > 24…

- - - - Raine (1997) found 41 'NGRI' murderers who had less activity in prefrontal lobe and abnormal activity in amygdala vs control, and less activity in the left side of the hippocampus - localisation of emotion processing
        
        implications: biological causes for predisposition to violence --> consequences r.e. legal system? (could use R. v Smith (1980))
      - refers to one hemisphere carrying out a particular function
      - brain is contralateral --> left deals with right side and vice versa - e.g. right visual field is processed in left visual centre
      - left hemisphere is primarily for language processing
        
        Broca's area - responsible for production of language. damage here affects conjugations and syntax --> excessive or motor aphasia
        
        Tan - Broca (c.s.) - following a stroke, Tan could only say that word (Broca's aphasia) - caused by a lesion in the left frontal lobe (now known as Broca's area) which is responsible for co-ordination of muscle movements required to produce speech
        
        Wernicke's area - language processing. damage here affects ability to find a specific word, or understand language in written or spoken form --> receptive aphasia
        
        Peterson et al (1982) used brain scans to demonstrate brain activity during a listening task (Wernicke's area) and a reading task (Broca's area) ∴ language is localised to specific areas in the brain
        
        BUT Lashley (1950) removed areas of cortex in rats learning a maze and found no area to be more important than another in relation to learning - learning as a process may be too complex to be localised, but rather distributed across brain
      - righthemisphere is primarily for recognising emotions and spatial information
        
        Rueckert (2008) 22 men and 73 women completed a chimeric face task, with both sexes being more likely to say the face with the smile on the left was happier - emotion seen in left visual field processed in right hemisphere ∴ suggests lateralisation of function with contralateral processing
      - plasticity #
      - methodology issues - focus on case studies
        
        specific cases/conditions ∴ we can't generalise to the wider population
        
        the brain's 'wiring' in these patients may have been abnormal outside of the condition present (e.g. brain dominance)
        
        no one brain area truly acts independently of the rest ∴ localisation is only true to a point
  - - - Sperry (1968)
        
        conclusions
        
        corpus callosum is involved in conveying information between hemispheres
        
        each hemisphere independently responsible for processing motor/sensory activity for opposite side of the body
        
        language is lateralised mostly to the left hemisphere
        
        personality and intelligence unaffected by corpus callosum
        
        evaluation of Sperry's research
        
        implications
        
        quality of evidence- patients had varying levels of split brain
        
        ethics
        
        evidence against lateralisation of function - plasticity #
        
        strengths of methodolgy- multiple studies so higher validity
        
        unity of consciousness debate - human conscious is usually unified, but split brain results suggest divided consciousness (two-stream model)
- - - - daylight is an exogenous zeigtgeber, so we feel drowsy at night and alert during the day, in a cycle lasting 24 hrs
        
        Siffre - spent six months in isolation in a cave, deprived of exposure to natural light, and found that his body clock settled down to a rhythm of ~ 25 hrs - likely evolved due to the rotation of the earth being ~24 hrs
        
        Aschoff & Weber (1962) - studied participants living in a bunker with electric lights and no windows who were allowed to turn the lights on and off as they wished, and found that their cycles settled to 25-27 hrs ∴ sleep/wake cycle may be longer than 24 hrs without the influence of natural light
        
        BUT Czeisler (1999) was able to adjust circadian rhythms of participants from 22-28 hrs using dim lighting ∴ artificial light may be a confounding variable
        
        methodology issues
        
        small samples used small samples used ∴ generalisation to population may not be feasible due to effect of individual differences - Siffre later admitted that his internal body clock changed as he grew older ∴ age may affect already unique circadian rhythms even more
        
        self report --> researcher bias in reporting (mostly Siffre)
        
        practical applications
        
        shift work
        
        Bolvin et al (1996) night shift workers experience a circadian trough and period of reduced concentration around 6 am --> accidents more likely
        
        long-term disruption of rhythms causes change to biological systems - economic implications - loss of efficiency of workers and cost to NHS
        
        Czeisler suggests that companies where shift work is unavoidable should make shifts forward rotation - i.e. phase advance -> phase delay - output and morale increased significantly
        
        drug treatment
        
        circadian rhythms co-ordinate a number of body processes (e.g. heart rate/digestion/hormone levels)
        
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  - - - BUT it can also be influenced by exogenous factors such as light and female pheromones
        
        McClintok (1998) collected samples of pheromones from women in different stages of their menstrual cycle, and rubbed them on the lip of other women - 68% of women changed their cycles to coincide with the cycle of the odour donor
        
        menstrual synchrony may be an evolutionary advantage - women living in communities will be pregnant and nursing at the same time, and learning mothering behaviours together
        
        BUT Schank (2004) suggests that too many women cycling together within a social group would make competition for the most fertile males ∴ a lack of synchrony would be more beneficial
        
        Reinberg (1967) spent three months in a cave with only lamp light, and found that her day lengthened to 24.9 hrs and her menstrual cycle shortened to 25.7 days
        
        TST the menstrual cycle is internally moderated by endogenous pacemakers , which control infradian rhythms - the cycle settled down after a change in exogenous zeitgebers
        
        methodology issues
        
        there are many factors that can affect a woman's menstrual cycle: e.g. stress; diet; sleep; supplements; contraception/hormonal medication
        
        cave studies are self-report (∴ we cannot guarantee that results are reported accurately) AND are also case studies (∴ raises issues with generalisability)
    - - practical applications: phototherapy
        
        Eastman et al. (1998) found that photo therapy relieved symptoms of SAD sufferers; however, they also found a 30% placebo effect ∴ phototherapy is somewhat effective BUT this might be partially psychosomatic
        
        methodology issue: self report
        
        Terman (1998) exposed participants with SAD to bright light in the:
        1) morning
        2) afternoon
        3) placebo
        and found that group 1 experienced a 60% improvement in mood, with group 2 and 3 having 30% and 5% improvement respectively
        
        TST light exposure reduces SAD symptoms by reducing melatonin production, which is most useful first thing in te morning (reduced placebo effect = :check:)
  - - - AWAKE: brain shows β activity
        STAGE I: short; θ waves
        STAGE II: 20 mins; bursts of high frequency sleep spindles
        STAGE III: 15 mins; 𝛿 waves; deep sleep
        STAGE IV: 40 mins; mainly 𝛿 waves; h.r., b.p. and temperature fall
        then we go backwards until...
        
        REM sleep: 10-60 mins; brain is active, causing dreams
        
        1 cycle takes ~90 mins, with up to 5 cycles per night
        
        Derment & Kleitman (1957) monitored the sleep patterns of 9 adult participants, and found that REM sleep correlated highly with experience of dreams, and that brain activity varied according to the vividness of dreams
        
        TST dreams are experienced in REM sleep, and also supports the idea that sleep cycles go through sequential stages
        
        methodology issues
        
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        methodology issues with investigating sleep patterns
        
        sleep labs --> low ecological validity due to artificial situation
        
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        no accounting for individual differences (e.g. a person's normal sleep schedule)
        
        dreaming can be affected by lifestyle/stress/diet ∴ % of dream recall may vary #
        
        further research
        
        Siegel (2003) found that the amount of REM sleep is proportional to the immaturity of the offspring at birth - e.g. a platypus has ~8 hrs whereas a dolphin has none --> REM is essential for brain maturation
        
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        Derman (1960) investigated the effects of REM deprivation, and found that the more participants were deprived on REM, the more they attempt to enter REM sleep, and when allowed to sleep uninterrupted they increased time spent in REM over the next 5 days until they recovered the REM they had lost (REM rebound)
        
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    - - issue with stage theory: ignores individual differences - not everyone goes through the set stages (e.g. lucid dreamers go straight to REM from being awake) ∴ stage theory restricts understanding of ultradian rhythms
  - - - lies just above optic chiasm and receives information about light directly from this structure, even when eyes are closed
        
        passes on information to pineal glad - increases prod. of melatonin