Localisaton of function

• Localisation versus holistic 


  Hollistic - all parts of the brain invovlved in processing thought and action

  Localisation of function - Idea different parts if the brain perform different tasks and are involved w different parts of the body - If certain parts of brain become damaged through illness or injury the function associated with that area will also be affected
• Hemispheres of the brain

  Main part of brain divided into two symmetrical halves called left and right hemisphere

  Some of our physical and psychological functions are controlled or dominated by particular hemisphere - lateralisation

  As general rule activity on left hand side of body controlled by right hemisphere, right hand side of the body left hemisphere.
• Motor, somatosensory, visual and auditory centres

  Cerebral cortex - outer layer od both hemispheres

  Cortex of both hemispheres subdivided into 4 centres called lobes - frontal lobe - personality, parietal lobe - sensory info, occipital lobe - vision and temporal lobe - auditory info - each diff functions
• Motor area


  At back of frontal lobe (both hems)

  Controls voluntary movement in opposite side of body

  damage to area may result in loss of control over fine movements
• Somatosensory area 


  Separated from motor area by valley called central sulcus

  where sensory info from skin is represented

  Amount of somatosensory area devoted to particular body part denotes its sensitivity eg receptors for our hands and face occupy over half som area
• Visual area 


  In the occipital love at back of brain

  Each eye sends info from right visual fields to left visual cortex and from left visual field to right visual cortex

  Damage to left hemisphere can produce blindness in part of right visual field of both eyes
• Auditory area 


  In temporal lobe - Wernickes area

  May affect ability to comprehend language
• Language centres of brain - Broca 


  Language is restricted to left side of brain in most people

  1800s Broca identified small area in the left frontal lobe responsible for speech production -

  damage to Brocas area causes Broca's aphasia characterised by speech that is slow, laborious and laking in fluency

  Brcoa patient Tan, tan was only word he could say

  Ppl with this have difficulty with prepositions and conjunctions.

  words,
• Wernicke

  Around same time Wernicke was describing people who has no problem producing language but severe difficulties understanding it such as speech they produced was fluent but meaningless - Wernickes area in left temporal lobe responsible for language undertsanding

  Results is Wernickes aphasia when damaged - produce nonsense
• S -Evidence from neurosurgery

  Damage to areas of brain linked to mental disordere

  Cingulatomy involved isolating a region called cingulate gyrus which is implicated with OCD

  Douherty et al reported on 44 people with OCD who had undergone cingulatomy at post surgical follow up

  after 32 weeks about 30% had met criteria for successful response to the surgery and 14% for partial response

  --> success of these procedures suggest behaviours associated with serious mental disorders may be localised
• Evidence from brain scans

  Supports idea that many everyday brain functions are localised

  Peterson used brain scans to demonstrate how Wernickes area was active during listening task and Brocas area active during a reading task

  Also review of LTM studies by Buckner and Peterson revealed that semantic and episodic memories reside in different parts of the prefrontal cortex

  --> confirm localised areas for everyday behaviours - therefore objective methods for measuring brain activity have provided sound scientific evidence that may brain functions are localised.
• Language localisation questioned


  Language may not be localised just to Brocas and Wernicked areas

  Recent review by Dick and Tremblay found only 2% of modern researchers think language in brain is completely controlled by Brocas and Wernickes areas.

  Advances in brain imaging techniques such as fMRI mean neural processes can be studied with more clarity - language function distributed more holistically than was thought - lang streams have been identified across cortex including brain regions in right hemisphere.

  --> language may be more holistic
• Hippocampus - in charge of LTM, creates long term memory

  Amigdala - memory consolidation and emotional regulation

  Hypothalamus - controls homeostasis

  Medulla - controls involuntary actions