localisation of function

• 4 sections of the brain

  • frontal lobe
  • parietal lobe
  • temporal lobe
  • occipital lobe
• motor area


  • within frontal lobe
  • regulates movement
• somatosensory area


  • within parietal lobe
  • processes sensory information (eg. touch)
• visual area


  • within occipital lobe
  • receives and processes visual information
• wernicke's area


  • within temporal lobe
  • language and understanding
  • left side only
• auditory area


  • within temporal lobe
  • concerned with analysis of speech
• broca's area


  • within frontal lobe
  • responsible for speech production
  • left side only
• brain 


  .

  
• localisation of function eval - :) evidence from brain scans


  • if people listen to poetry in an fMRI scanner the wernicke's area lights up
  • if they read poetry the broca's area lights up
  • scientific evidence
• localisation of function eval - :) case study evidence 


  • phineas gage - left frontal lobe damage caused personality changes
  • BUT... anecdotal, lack of reliable evidence
• localisation of function eval - :) evidence from neurosurgery


  • patients can be awake during neurosurgery
  • stimulating these areas can be associated with their function - eg. stimulating broca's area can cause slurred speech
• localisation of function eval - :( counter evidence from lashley

  • removed areas of cortex (10% - 50%) in rats that were learning a maze
  • no area proved to be more important, the process of learning require every part of the cortex
  • not localised but holistic
  • learning is too complex to be localised
• localisation of function eval - :( concept of plasticity


  • contradicts idea of localisation of function
  • brain can require / reorganise itself following damage (eg. girl with half a brain)
• lateralisation of function


  • each hemisphere controls the opposite side of the body
  • left = right , right = left
  • each hemisphere is specialised to certain things eg. language is specialised into the left hemisphere
• split brain surgery

  corpus collosum is cut in half in extreme epilepsy cases

  • people dont have many day to day side effects from this
  • seizures are restricted to one half of the brain as the nerve endings have been cut and cant jump across to the other side
• corpus collosum

  connects our 2 brain hemispheres

  communicating them constantly , cant separate
• sperrys split brin experiments 


  • those that have had split brain surgery sit in front of a screen and a word flashes briefly to the right field of view, and patient is asked what he saw
  • because left hemisphere is dominant for verbal processing, patients answer matches the word
  • now a word is flashed to left field of view and patient is asked what he saw
  • right hemisphere cannot share information with left , so the patient is unable to say what he saw, but can draw it
  • this confirms there are differences between the hemispheres. eg. left hemisphere responsible for speech and language
• briefly explain how unusual behaviour in split brain patients could be tested in an experiment 


  split brin patients can be tested by showing words or objects to only one visual field (and therefore is only processed in 1 hemisphere) and seeing if they can do things such as say the word, match the object or draw it. for example, show them the word 'key' to their left visual field and see if they can say the word or if they can select a key from a group of hidden objects with their left hand
• sperry split brain exp eval - :( his findings cannot be generalised 


  • based on 11 patients with epileptic seizures
  • unique brain changes may have influenced findings, so therefore may not apply to 'healthy' patients
• sperry split brain exp eval - :( differences between the hemispheres have been exaggerated 


  • modern neuroscientists would say the brain is much less clear cut then suggested here.
  • eg. apart from 'verbal' and 'non verbal' labels only apply on occasion, and brain function is much more 'messy'
  • the fact that hemispheres can perform other hemispheres tasks when required suggests the theory is inaccurate
• sperry split brain exp eval - :) use of standardised procedures 


  • allowed sperry to have high controls and vary aspects of the basic procedure
  • this provides validity to the results and allows it to be easily replicated
• sperry split brain exp eval - :) in addition to original procedure, sperry has further demonstrated lateralisation 


  • results show left hemisphere controls speech + language, and right side controls visual information and face recognition, indicating different sides of the brain perform different functions
  • however sperrys research and a few repeats are the only evidence for this theory and the fact later research contradicts this limits validity of the study
• sperry split brain exp eval - :( recent evidence challenges idea language is restricted to the left hemisphere 


  • gazzinga - patient case study with capacity to speak out of right hemisphere, could then speak about info presented to the left or right side of the brain, despite one sided brain damage
  • therefore contradicts theory as language may not be restricted to left hemisphere + suggests brain has plasticity, therefore the theory is too simplistic
• sperry brain exp eval - :) research suggests there are advantages to hemispheric lateralisation 


  • tonnessan - found in domestic chickens, lateralisation is associated with an enhanced ability to perform 2 tasks simultaneously - finding food and being vigilant for predators
  • suggests lateralisation aids brain efficiency in cognitive tasks, and therefore is an advantageous characteristic for survival
• plasticity 


  • has the ability to modify its own structure and function as a result if experience
  • as people gain new experiences the nerve pathways that are used frequently develop stronger connections
  • nerve pathways that are rarely / never used eventually die (pruning away)
  • originally thought these changes were restricted to childhood but recent work suggests neural connections can be formed at any age
• functional recovery of the brain 


  • unaffected areas of the brain often adapt and compensate for damaged areas
  • brain can rewire and reorganise itself by forming new synaptic connections close to area of damage
  • dormant synapses that wouldn't typically be used are activated to allow functioning to continue
  • stem cells can also be used to provide treatments for brain damage
  • stem cells- unspecialised cells which have potential to give rise to different cell types including neurons
• plasticity - elbert et al


  • violinist relies on more finger dexterity in their left hand, much less required in right hand
  • brain scans of somatosensory cortex in violinists reveal an unusually large region devoted to fingers of left hand, larger than region supporting movement in right hand
  • asymmetry suggests brain has responded to the demands placed upon it and he brain adapts by recruiting neuron to help support finger control in left hand
• plasticity - maguire et al 


  • in london taxi drivers are presented with a layout of streets that is quite hard to learn
  • in this study the demands of long term memory and spatial reasoning were significant as it was done before use of satnavs
  • brain scans of 16 london taxi drivers showed particularly large posterior hippocampus, region supporting 2 dimensional spatial processing
  • was largest in taxi drivers with over 40 years experience
• plasticity - may


  • divided group of 24 non jugglers into 2 groups, asking 12 Ps to learn how to juggle, other 12 as a control group
  • after 3 mths all 12 in experimental group were successful in juggling for at least 60 secs
  • brain scans taken before + after learning show changes in regions specific to visualisation in temporal lobes
  • volume of those areas increased average of 3%, no changes in the brains of control group
  • 3rd scan 3 mths later (no juggle during this time) showed structural changes had reversed partially
  • concluded human brains macrostructure can change in response to training
• example answer

  • after road accident josie damaged brocas area in her left hemisphere (responsible for speech), and also in her left hemisphere her wernicke's area was damaged (responsible for understanding).
  • in her recovery it would involve the recruitment of homologus areas, which used existing structures in the opposite hemisphere to enable a route to be used without having to build new networks
  • allows her right hemisphere to take over
  • easier for her brain due to her young age o 12 as she has more neuroplasticity as opposed to an older person who would find it more difficult
• recruitment of homologous areas 


  using existing structures on the opposite hemisphere to enable a route to be used without having to build new networks
• axonal sprouting 


  growing new nerve endings to join undamaged neurons, creating new pathways
• reformation of blood vessels 


  supporting and reinforcing the new neural pathways with blood vessels