localisation of function in the brain

• Localisation of function

  Different parts of the brain are responsible for specific behaviours, processes or activities.
• Function of Motor cortex


  Voluntary muscle motor movements across the body.

  At the back of the frontal lobe.

  Contralateral

  Damage: injuring results in the loss of muscle function or after severe trauma, paralysis on the opposite side of the body
• Function of Somatosensory cortex


  Receives sensory information from the body and produces sensations such as touch and pain.

  Contralateral

  Front of the parietal lobe

  Damage: Loss of sensation in opposite side to damage, ignoring areas of the body.
• Function of Broca's Area


  Responsible for speech production

  In the left frontal lobe only.

  Damage: motor aphasia/difficulty producing fluent speech
• Function of Wernicke's area


  Responsible for speech comprehension

  Located in the Left temporal lobe.

  Damage: sensory aphasia/difficulty understanding speech.
• Function of Auditory cortex


  Receives and processes sound information from ears.

  Located in both hemispheres

  Damage: lead to cortical deafness - patient unable to hear but no damage to ear.
• Function of visual cortex (occipital lobe)


  Visual processing

  Each hemisphere receives information from opposite visual field.

  Damage: partial or complete loss of vision.
• Hemispheric Lateralisation


  Each hemisphere of the brain is specialised to perform different functions.

  Left - Language centres

  Right - Visual-spatial processing
• Contralateral


  Each hemisphere of the brain controls the opposite side of the body. Including both motor and sensory pathways and vision of the contralateral visual field.
• + Supporting evidence from case studies


  E - Clinical case study research demonstrates loss of certain function if damage is caused to particular areas of the brain e.g. broca and wernicke's case studies (aphasia) and Clive Wearing (amnesia).

  E - This suggests functions are localised in these areas

  L - However, case studies cannot generalise to everyone.
• / Case studies are not generalisable


  E - The use of case studies are seen as unscientific, especially in brain research with damage often covering multiple regions - as seen in the case of Tans brain.

  E - It is hard to generalise findings of what happened to a singular person as it may not happen to everyone.

  L - Therefore, the use of case studies to support localisation of function may not be valid and can't be generalised.
• + Supporting evidence


  E - Petersen used brain scans to demonstrate how the Wernicke's area was active during a listening task and the Broca's area was active during a reading task.

  E - This confirms that different areas of the brain are responsible for different tasks.

  L - Furthermore, Petersen's research was conducted in a lab environment, meaning it has high internal validity as the variables were controlled.
• + Practical applications


  E - Dougherty reported on 44 people with OCD who had undergone a surgery to isolate an area of the brain implicated in OCD.

  E - 30% had a successful response to the surgery and 14% had a partially successful response.

  L - The success of these procedures demonstrates how behaviours associated with serious medical conditions may be localised.