localisation of brain function

• localisation of brain function - the theory that different areas of the brain are responsible for different behaviours, processes or activities

  • the opposite view is the holistic view - the theory that all parts of the brain are involved in processing thought and action
• lateralisation - the theory that certain physical and psychological functions are controlled by a particular hemisphere
• hemispheres and the cerebral cortex

  • the brain is divided into two symmetrical halves called hemispheres separated by the corpus collosum
  • the two hemispheres have different roles
  • in general the left side of the body is controlled by the right side of the brain and vice versa
  • the outer layer of the brain is called the cerebral cortex (grey matter) - plays a key role in memory, attention, consciousness and thought
• the frontal lobes

  • controls voluntary movement in the back of the frontal lobe - motor cortex - and damage to this area can cause loss of fine motor control
  • other functions include attention, planning, motivation and problem solving

  
• parietal lobes

  • the front of the parietal lobes - somatosensory cortex - processes sensory information from the skin
  • some parts of our body are more represented than others, which denotes the sensitivity of different body parts
  • separated from the motor cortex by the central sulcus

  
• occipital lobes

  • contains the visual cortex which receives and processes visual information
  • each eye sends information from the right visual field to the left visual cortex and vice versa
  • this means damage to the left hemisphere can produce blindness in the right visual field

  
• temporal lobes

  • houses the auditory area - analyses speech-based information
  • damage to this area may produce hearing loss
  • wernicke's area is found in the left temporal lobe which controls language comprehension

  
• the language areas of the brain

  language areas are located in the left side of the brain

  • wernicke's area - responsible for language comprehension
  • damage results in wernicke's aphasia - speech is fluid but meaningless
  • broca's area - responsible for speech production
  • damage results in broca's aphasia - slow speech that is labourious and lacks fluency
• evidence of localisation

  • brain scans - look at which part of the brain is active during each task
  • neurosurgical evidence - removing certain parts of the brain to control aspects of behaviour
  • case study evidence - shows how damaging a certian part of the brain affects behaviour
• examples of localisation

  • types of ltm - tulving et al. found that episodic and semantic memories were retrieved in different parts of the brain
  • prefrontal cortex - phineas gage suffered damage to his prefrontal cortex which made him aggressive and irritable
  • types of stm - kf case study could remember words he read but not that he heard aloud after a motorbike accident, which suggests they are stored in different parts of the brain
• evidence against localisation

  • lashley - research on rats which suggests higher cognitive functions such as learning aren't localised but distributed in a holistic way
  • however this may be different localised areas working in tandem
  • plasticity - the brain's ability to recover after trauma which suggests parts of the brain can take over the role of damaged parts