localisation of function

• Define Localisation of function

  Functions such as movement, speech and memory are performed in distinct regions of the brain (localised). The opposite view is the brain acts holistically to perform functions.
• Define Hemispheric Lateralisation

  Each hemisphere of the brain is specialised to perform different functions. (language centres are in the left hemisphere, visuospatial tasks are best performed by the right) Motor, somatosensory, visual and auditory cortices are on both sides of the brain. Broca /Wernicke's area only in the on left hemisphere
• Define 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.
• Describe the function of the Motor Cortex

  Voluntary muscle motor movements across the body. Contralateral. At the back of the frontal lobe and separated from the somatosensory cortex by a fold called the central sulcus.

  Damage: Injuring results in the loss of muscle function or after severe trauma, paralysis on the opposite side of the body
• Describe the function of the Somatosensory Cortex

  Receiving sense impressions from around the body. Contralateral. front of the parietal lobe and separated from the motor cortex by a fold called the central sulcus.

  Damage: Loss of sensation in opposite side to damage, ignoring areas of the body (neglect syndrome)
• Describe the function of Broca’s Area

  Located in the left frontal lobe only, Broca’s area is responsible for speech production

  Damage: motor aphasia/ Difficulty producing fluent speech
• Describe the function of Wernicke’s Area

  Located in the left frontal lobe only, responsible for speech comprehension Damage: sensory aphasia / Difficulty understanding speech
• Describe the function of Auditory Cortex

  Receives and processes sound information from ears. Located in both hemispheres
• Describe the function of Visual Cortex (Occipital Lobe)

  visual processing each hemisphere receives info from the opposite visual field.
• How where many of the localised functions of the brain originally discovered?

  Clinical case study research demonstrated the loss of certain functions if damage is caused to particular areas of the brain e.g. Broca and Wernicke's case studies suggesting functions are localised in these areas
• Describe how Lashley (1925) contradicts localisation of function.


  50 rats ran a maze before and after areas of their brain cortex were destroyed. Found ability to successfully re-run the maze was affected by how much brain cortex was destroyed not which areas.
• What functions are not localised?

  Systems like language are more distributed than motor/sensory and some functions like consciousness and long term memory storage appear to not be localised at all