Biopsych names

• Dougherty et al (2002) reported on 44 people with OCD patients who had undergone a cingulotomy - a neurological procedures that involved lesioning of the cingulate gyrus.

  post-surgical follow up after 32 weeks, a third (about 30%) had met the criteria for a successful response to the surgery and 14% for partial response.

  The success of these procedures suggests that behaviours associated with serious mental disorders may be localised
• Peterson et al used brain scans to demonstrate how Wernicke's area was active - listening task

  Broca's area active - reading task
• Review of long-term memory studies - Buckner and Peterson

  revealed semantic and episodic memories reside in different parts of prefrontal cortex

  Therefore - objective methods for measuring brain activity provided sound scientific evidence that many brain functions localised
• Lashley - removed areas of the cortex (10-50%) in rats learning route through a maze

  No area proven to be more important than any other in terms of ability to learn route

  Process of learning seems to require every part of cortex rather than confined to particular area

  Suggests that higher cog processes, e.g. learning, not localised but distributed in more holistic way in brain

  Equipotentiality
• Review by Dick and Tremblay - only 2% modern researchers think language completely controlled by Broca's and Wernicke's

  Advances in brain imaging techniques - fMRI - mean that neural processes in brain can be studied with more clarity

  seems language function distributed more holistically than first thought

  Language streams have been identified across cortex - including brain regions in right hemisphere, as well as subcortical regions e.g. thalamus

  Suggests that rather than being confined to couple key areas, language may be organised more holistically in brain - contradicts theory
• Bravelier - study of silent reading

  Found large variability in individual patterns of activation across different individuals

  Observed activity on the right temporal lobe as well as in left frontal, temporal and occipital lobes
• Other studies have found gender differences in size of brain areas associated with language

  Harasty et al - women have proportionally larger Broca's and Wernicke's than men

  result of women's greater use of language

  Suggests level of beta bias in theory, whereby differences between men and women ignored and variations in pattern of activation and size of areas observed during various language activities not considered - reduces validity
• Rogers et al found that in domestic chickens, brain lateralisationis associated with an enhanced ability to perform two tasks simultaneously - finding food and being vigilant for predators

  this provides some (yet limited) evidence that lateralisation enhances brain efficiency in cognitive tasks that demand simultaneous but different use of both hemispheres
• Lateralisation


  Language becoming more focused in one hemisphere of the brain
• Increasing age in children and adolescents


  Language becomes more lateralised to the left hemisphere
• After age 25


  Lateralisation decreases with each decade of life
• It is difficult to know why this happens
• Compensation


  Using the extra processing resources of the other hemisphere may in some way compensate for age-related declines in function and so brain functions become more balanced between hemispheres
• This is a limitation to the theory because it is only applicable to younger people and not necessarily applicable as our brains mature, reducing validity
• case studies have demonstrated that this was not necessarily the case e.g. one patient known as J.W. developed the capacity to speak out of the right hemisphere, with the result that J.W. can now speak about information presented to the left or to the right brain (Turk et al)

  However - case study - lacks generalisability
• Gazzaniga suggests that some of the early discoveries from split-brain research have been disconfirmed by more recent discoveries e.g. split brain research suggested that the right-hemisphere was unable to handle even the most rudimentary language. Damage to the left hemisphere was found to be far more detrimental to language function than damage to the right
• Nielsen et al analysed brain scans from over 1000 people aged 7 to 29 years and did find that people used certain hemispheres for certain tasks (evidence for lateralisation). but there was no evidence of a dominant side i.e. not artist's brain or mathematicians brain.
• Fink et el used PET scans to identify which brain areas were active during a visual processing task. when participants with connected brains were asked to attend to global elements of an image (such as looking at a picture of a whole forest) regions of the RH were much more active. when requires to focus on on the inner detail (such as individual trees) the specific areas of the LH tended to dominate. this suggests that, at least as far as visual processing is concerned, hemispheric lateralisation is a future of the connected brain as well as the split-brain.
• small sample size (1 female) - though not relative to target pop - Andrews argues that many studies have only 3 (sometimes even just one) PP
• limitation of Sperry's research is that causal relationships are hard to establish.

  Behaviour of Sperry's split-brain PPs was compared to neurotypical control group

  An issue though is that none of the PPs in the control group had epilepsy - major confounding variable

  Any differences observed may have been result of epilepsy rather than split brain

  Means that some of the unique feature of split-brain PPs cognitive abilities may have been result of epilepsy
• Kingstone et al in the normal brain, the LH's better cognitive strategies are 'watered down' by the inferior RH - supports Sperry's earlier findings that the 'left brain' and 'right brain' are distinct
• Luck et al (Gazzaniga) Showed that split-brain PPs actually perform better than connected controls on certain tasks e.g. faster at identifying the odd one out in an array of similar objects than controls with connected brains
• Tajiri et al provided evidence for the role of stem cells in recovery from brain injury

  Randomly assigned rats with traumatic brain injury to one of 2 groups

  one group received transplants of stem cells into region of brain affected by traumatic injury

  control group received solution infused into brain containing no stem cells

  3 months after brain injury - brains of stem-cell rats showed clear development of neuron like cells in area of injury

  accompanied by solid stream of cells migrating to brain's site of injury

  not the case with control group
• Evaluation of Tajiri et al: hard to generalise to humans

  animal studies enable us to monitor function of brain before and after - cause the injury

  ethically couldn't do to humans - unlikely we would have measured their functioning before natural event

  easier to establish cause and effect

  controlled how trauma administered - very tightly controlled
• studies in 2010 and 2011 using fMRI techniques have shown that parts of brain associated with visual processing adapted for new skill of echolocation

  Studies with blind patients suggest that click-echoes heard by these patients were processed by brain regions devoted to vision rather than audition

  In humans - evidence restricted to small scale studies of people who already have the issue - unclear if what we are seeing is due to recovery or an individual difference

  small sample size - not blind from birth - learning echolocation
• Research ongoing for new treatments to aid functional recovery

  e.g. study by Banerjee et al treated people who had a total anterior circulation stroke (TACS) with stem cells

  all patients in trial recovered compared to more typical level of 4% recovery

  however, drew conclusions based on 5 PPs and no control group - typical of research on functional recovery

  not representative

  issues with generalisation/ individual differences
• commonly accepted view that functional plasticity reduces with age (Huttenlocher)

  According to view only option following traumatic brain injury beyond childhood is to develop compensatory behavioural strategies to work around deficit (such as seeking social support or to develop strategies to deal with cognitive deficit)

  However studies have suggested that even abilities commonly thought to be fixed in childhood can still be modified in adults with intense training
• Despite these indications of adult plasticity, Elbert et al conclude that capacity for neural reorganisation is much greater in children than in adults, as demontrated by the extended practice that adults require in order to produce changes - brain still capable at later age and medical intervention

  still greater in children - adults need far greater medical intervention physiotherapy etc to get to same level of recovery rate
• Schneider et al - found that patients with the equivalent of a college education are 7x more likely than those who didn't finish high school to be disability-free one year after a moderate to severe traumatic brain injury

  Carried out retrospective study (secondary data) based on data from the US Traumatic Brain Injury Systems Database

  of 769 patients studies 214 had achieved disability-free recovery after 1 year

  of these 39.2% of patients with 16 or more years education and just 9.7% of those with 12-15 years education achieved DFR after 1 year
• researchers concluded that 'cognitive reserve' (associated with greater educational attainment) could be a factor in neural adaptation during recovery from traumatic brain injury

  not everyone's brain has same capacity for recovery

  more learning = more likely to functionally recover

  creating cognitive reserve - brain can do more neural unmasking - more connections to use
• real-world app

  understanding processes involved in plasticity has contributed to field of neurorehabilitation

  simply understanding that axonal growth is possible encourages new therapies to be tried

  e.g. constraint-induced movement therapy is used with stroke patients whereby they repeatedly practise using the affected part of their body (such as an arm) while the unaffected arm is restrained

  this shows that research into functional recovery is useful as it helps medical professionals know when interventions need to be made
• Evidence has shown that the brain's adaptation to prolonged drug use leads to poorer cognitive functioning in later life as well as increased risk of dementia (Medina et al)
• 60-80% of amputees known to develop phantom limb syndrome - continued experience of sensations in the missing limb as if it was still there

  These sensations usually unpleasant, painful and thought to be due to cortical reorganisation in somatosensory cortex that occurs as a result of limb loss (Ramachandran and Hirstein)

  Suggests that brain's ability to adapt to damage not always beneficial
• However, Bezzola et al demonstrated how 40 hrs of golf training produced changes in neural representations of movement in PPs aged 40-60

  using fMRI researchers observed reduced motor cortex activity in novice golfers compared to control group

  suggesting more efficient neural representations after training

  Shows that neural plasticity can continue throughout the lifespan
• Research suggests may be seasonal plasticity in brain in response to environmental changes

  e.g. consider SCN which regulates sleep/wake cycle

  evidence of this particular brain structure shrinking in all animals spring spring and expands throughout autumn

  (Tramontin and Brenowitz)

  However, much of work on seasonal plasticity done on animals - notably songbirds

  human behaviour may be controlled differently
• Methodologically sound study


  • Control group allows us to say that there is a significant difference between taxi drivers and non-taxi drivers (cause and effect)
  • Matched pairs design minimises participant variables - greater validity
  • Use of scientific, objective measurements (MRI)
  • Double-blind technique - person doing pixel counting did not know whether taxi or non-taxi - avoid investigator effects
  • Scan of brain - high ecological validity
• Difference between taxi drivers and non-taxi drivers

  May not be due to 'The Knowledge' as PPs were not tested before - may be good taxi drivers due to an existing difference
• Positive correlation between experience and structure


  Makes it likely to be the cause
• Quality of this research/ evidence makes it a very valid study
• One limitation is that exogenous zeitgebers do not have the same effect in all environments

  experience of people who live in places where there is very little darkness in summer and very little light in winter tell a different story from usual narrative

  e.g. people who live in the Arctic Circle - Inuits of Greenland have similar sleep patters all year round, despite spending around 6 months in total darkness

  suggests the sleep/wake cycle is primarily controlled by endogenous pacemakers that can override environmental changes in light