Biopsychology (not yet finished)

  • Created by: dgavan
  • Created on: 22-05-19 15:12
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  • Biopsychology
    • Localisation of function
      • Diff areas of the brain are responsible for diff functions; when one area of the brain is damaged, the associated function is affected
      • LH = movement, vision, hearing, reading, writing and speaking
        • LH controls RHS of body and vice versa
      • RH = art, creativity, music etc
        • LH controls RHS of body and vice versa
      • Cerebral cortex is about 3 mm thick and covers both hemispheres; more dev.ed in humans which makes us more cog developed
      • Broca's area in LH frontal lobe and responsible for speech production
        • Damage can lead to B's aphasia, which leads to slow and influent speech
      • Wernicke's area in LH temporal lobe and controls speech comprehension
        • Damage can lead to W's aphasia which causes fluent yet nonsense speech
      • Areas
        • Motor area controls fine motor skills and voluntary movement. Located in frontal lobe and separated from somatosensory area by central sulcus
        • Somatosensory area receives info from skin and controls involuntary movement. Located in the parietal lobe and separated from motor area by central sulcus
        • Visual area receives info from eyes; damage to LH causes blindness in the right visual field of both eyes. Located in the occipital lobe
        • Auditory area receives info from ears; damage to LH causes right ear deafness. Located in temporal lobe.
      • Evaluation
        • (+) Tulving (1994) did PET scans and found diff areas of the brain were active for episodic vs semantic memories
          • BUT lack of clarity over what area of the brain is responsible for procedural memories so incomplete
        • (+) Peterson (1988) found B's area was active when reading aloud vs W's area active when listening
        • (-) Lashley removed 10-50% of rats' brains from varying areas and found they all couldn't complete a maze
          • Suggests a holistic model
        • (+) Dougherty (2002) found 1/3 of OCD patients who got a cingulotomy improved and a further 14% showed partial improvement
        • Phineas Gage (1848); had his frontal lobe removed in an accident and his personality changed dramatically
          • BUT case study evidence
        • (-) Plasticity
    • Hemispheric lateralisation and split brain research
      • LH = language skills
        • Work independently from one another; info from LVF enters RHS of eyes and hits RHS of occipital lobe
          • RH = visuo-spatial skills
      • RH = visuo-spatial skills
      • Sperry (1968) studied 11 epileptics who'd received a commisurotomy (removal of corpus collasoum to separate LH and RH)
        • (1) Gave ppts an image in each visual field; ppts could describe the RVF image but not the LVF one, but ppts could only pick out a matching object (with their left hand only) for the LVF image
        • (2) Words; "key" in LVF and "ring" in RVF; ppts would write "key" (visuo-spatial task) using their left hand only, but say "ring"
        • (3) Diff faces in LVF and RVF; could only match LVF faces accurately to photos
      • Evaluate
        • (+) Allows quick diagnosis as we can examine which functions are lost, then see which part of the brain we need to look at
        • (-) Modern neuroscientists argue that it's led to an oversimplification of functional diffs bet LH and RH
        • (-) V small sample, and there may also be extraneous variables as they're all epileptic patients
        • (+) Lab study; each object was in one VF only
    • Plasticity and functional recovery after trauma
      • Gopnik et al found we've got ~15,000 synaptic connections @2-3 yrs old (twice as many as in adulthood)
        • Plasticity reduces as we age; rarely used connections are weakened/ deleted which frequently used ones are strengthened (synaptic pruning)
      • Old view: brain can only change in childhood and is then fixed and set in adulthood
      • New view: synaptic connections can be edited at any age, and new ones can be forged through learning ad experience (although plasticity does reduce w/ age
      • Maguire (2000) found sig higher posterior hippocampus volume (linked to space and memory) in London cab drivers than a non-cab driver control group
      • Draganski (2006) found sig changes in vol of grey matter in posterior hippocampus in med students 3 months before their exam vs straight afterwards
      • Brain can repair itself after illness/injury, but this slows down over time so rehabilitative therapy may be required
        • 1) Axonal sprouting; new neural pathways form as new nerve endings grow
        • 2) Blood vessel reformation
        • 3) Recruitment of homologous areas; similar area on opposite hemisphere may take over function lost (done via the new nerve endings)
    • Ways of investigating the brain
      • fMRI (functional magnetic resonance imaging) detetcs changes in blood flow and oxygenation due to neural activity
        • Haemodynamic response; more blood flow and oxygen needed for areas w/ higher neural activity
        • Produces 3D images called activation maps
        • (+) High spatial resolution; mm by mm detail
        • (-) Low temporal resolution; ~5 sec time lag
        • (+) No radiation used so safe for children
          • (-) Patient must remain perfectly still so maybve not suitable for children
        • (-) Patient must remain perfectly still so maybve not suitable for children
        • (-) Very expensive
      • EEGs (electroencephalograms)
        • Patients wear a skull cap to attach electrodes to patient's scalp
        • Records electrical activity in the brain from the actions of millions of neurons; gives an overall account of brain activity.#
        • Produces raw, unprocessed data
        • (+) Useful in epilepsy diagnosis; caused by random short bursts of activity in the brain
        • (+) V high temporal resolution; lag time of ~1 millisecond
        • (-)  Only gives a generall overview; can't pinpoint the cause of beh
        • (+) Useful in understanding the stages of sleep
      • ERPs (event related potentials)
        • Uses a statistical averaging technique to filter out the unnecessary data from EEGs to give just the relevant stuff; called an event-related potential
        • (+) Derived from EEGs so v high temporal resolution
        • (+) Way more specific than EEGs; P300 component links to allocation of attentional resources and maintenance of the WMM
        • (-) Must get rid of all background noise for ERPs to be effective; impractical
        • (-) Lack of std.isation between research makes it diff to verify and compare
      • Post-mortem research
    • Biological rhythms
      • Circadian rhythms (once every 24 hrs); sleep wake cycle; melatonin is a hormone that's inhibited in daylight and makes us sleepy
        • Siffre (1962) spent 2 months in a cave and found his sleep-wake cycle settled at 25 hrs
          • Therefore s/w cycle is naturally about 25 hrs, not 24
            • Aschoff and Wever (1976) got ppts to spend 4 weeks in a WW2 bunker w/out natural daylight and found that one ppt's s/w cycle settled @ 29 hrs but the rest had 24-25 hrs
        • Aschoff and Wever (1976) got ppts to spend 4 weeks in a WW2 bunker w/out natural daylight and found that one ppt's s/w cycle settled @ 29 hrs but the rest had 24-25 hrs
        • Folkard had 12 ppts live in a cave for 3 months; ppts went to sleep at 11:45 and woke up at 7:45, but the researchers would adjust the clocks a little bit each time so that by the end of it the "days" were about 22hrs
          • Ppts couldn't adjust; shows s/w cycle is a powerful circadian rhythm
        • (+) Real life application; shiftworkers now get set amount of "reset days"
        • (-) Studies like Folkard, Aschof and Wever, and Siffre have poor sample sizes so poor generalisability
        • (+) Can be applied to drug therapy; if patients take drugs at he right time according to circadian rhythms then they can be more effective
        • (-) Ppts in supporting studies had some access to artificial light which we now know can affect the s/w cycle
      • Ultradian rhythms: (more than once every 24 hrs); stages of sleep. Each 90 min sleep cycle has 5 stages...
        • 1) Drowsy sleep; mostly alpha waves and then theta waves
        • 2) First "real stage of sleep; awareness of outer world fades; mainly theta waves
        • 3) Even less responsive to the outside world; mainly delta waves (which are slower than theta waves)
        • 4) Even deeper sleep; delta waves, very difficult to awaken
        • 5) REM sleep; brain activity speeds up and waves are more similar to the waking state
        • (+) Dement and Kleitman (1957) studied sleep patterns of 9 adults and found brain activty varied w/ vividness of dreams; this was higher in the REM stage; suggests REM is important
          • (+) Landmark study for the emergence of scientific sleep pattern analysis
          • (-) Small sample size so poor generalisability

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