Localisation of Brain Function

• What is the definition of localisation in the context of the brain?


  The theory that specific areas of the brain are associated with particular physiological and psychological functions
• What are the main centres of the brain?

  • Frontal lobe
  • Parietal lobe
  • Temporal lobe
  • Occipital lobe
• Where is the motor cortex located?


  In the back of the frontal lobe
• What is the primary function of the motor cortex?


  It is responsible for generating voluntary motor movements
• How does the motor cortex control movement?


  It controls movement in the opposite side of the body
• What might happen if the motor cortex is damaged?


  It may result in a loss of control over fine movements
• Where is the somatosensory cortex located?


  At the front of the parietal lobe
• What is the function of the somatosensory cortex?


  It detects sensory information from the skin and localises it to specific body regions
• How does the somatosensory cortex receive sensory information?


  It receives sensory information from the opposite side of the body
• Where is the visual cortex located?


  In the occipital lobe
• What is the role of the visual cortex?


  It processes visual information received by the retina
• How is visual information transmitted to the visual cortex?


  It is transmitted via the optic nerve to the brain
• Where is the auditory cortex located?


  In the temporal lobe
• What is the function of the auditory cortex?


  It processes auditory information received by the cochlea
• What may occur if the auditory cortex is damaged?


  It may produce hearing loss
• Where is Broca's area located?

  In the left frontal lobe
• What is the primary function of Broca's area?


  It is responsible for speech production
• What might happen if Broca's area is damaged?


  It may lead to difficulty producing speech (Broca's aphasia)
• Where is Wernicke's area located?


  In the left temporal lobe
• What is the function of Wernicke's area?


  It is responsible for speech comprehension
• What may occur if Wernicke's area is damaged?


  It may result in an inability to understand speech or produce coherent sentences (Wernicke's aphasia)
• Localisation AO3 - Higher cognitive functions not fixed


  • Lashley proposed the equipotentiality theory - suggests that the basic sensory and motor functions are localised but higher mental functions are not
  • Claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following brain injury
  • Reduces validity about the localisation of functions, suggesting that functions are not localised to just one region, as other regions can take over specific functions following brain injury
• Localisation AO3 - Research support


  • Research to support localisation of functions comes from brain scan research - wide range of evidence
  • Peterson et al used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task
  • Tulving et al have shown that episodic and semantic memories were recalled from different sides of the prefrontal cortex whilst procedural memory is associated with the cerebellum
• Localisation AO3 - Research against


  • Research against localisation comes from research into brain plasticity
  • Lashley found that when the brain becomes damaged through accident or illness and a particular function is compromised the rest of the brain is able to reorganise itself to recover the lost function, for example cases of stroke victims
  • Problematic as it suggests that the localisation theory may be too simplistic and the brain may be more adaptive and operate in a more holistic way
• Localisation AO3 - Interactions between areas of the brain


  • More important to investigate how the brain areas communicate with each other, rather than focusing on specific brain regions
  • Wernicke - although the different areas of the brain are independent, they must interact with each other in order to function
  • Damage to the connection between any two points can result in impairments that resemble damage to the localised brain region associated with that specific function
  • Reduces the credibility of the localisation theory as functions are not limited to one area of the brain