Localisation of Function in the Brain

• 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 (R/L) is specialised to perform different functions

  - language centres (Broca/Wernicke) are in LH, Visio spatial tasks are best performed by RH

  - motor, somatosensory, visual and auditory vortices are on both sides of the brain
• define contralateral


  - each hemisphere of the brain controls the opposite (contralateral) side of the body, including both motor and sensory pathways; and vision of the contralateral visual field
• describe the function of the motor cortex

  - 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

  - somatosensory cortex: receiving sense impressions from around the body

  - contralateral. front of the parietal lobe and separated from the motor cortex by a central sulcus fold

  - damage: loss of sensation on the opposite side to damage,ignoring areas of the body (neglect syndrome)
• describe the function of Broca's Area & Wernicke's Area

  - Broca's Area: located in the LH (frontal lobe) only, responsible for speech production; Damage: Broca's aphasia/difficulty producing fluent speech (Leborgne 'Tan'; lesion in frontal lobe of LH)

  - Wernicke's Area: located in LH (temporal lobe) only, responsible for speech comprehension; Damage: sensory aphasia/difficulty understanding speech
• describe the function of the auditory & visual cortex

  - auditory cortex: receives and processes sound info from the ears, located in both the LH and RH

  - visual cortex: processes visual info, located in each hemisphere (occipital lobe), both LH and RH receives visual info from the opposite visual field
• how were many of the localised functions of the brain originally discovered?

  - clinical case study research demonstrated the loss of certain functions if the damage is caused to particular areas of the brain

  - eg: Broca and Wernicke's case studies suggesting functions are localised in these areas
• describe how Lashley (1925) contradicts the localisation of function

  - 50 rats ran a maze before and after area 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 brain functions are not localised?

  - systems like language are more distributed than motor/sensory, and some functions like consciousness and LTM storage appear to not be localised at all
• outline the research by Heller and Levy (1981)

  - a series of photographs of faces that had been split (one half smiling, other neutral) were show to ppts

  - after each pair of photos had been shown, ppt asked which they thought was happier

  - generally, the emotion displayed on the LHS of the picture was the emotion recognised (presented in left visual field, RH dominant for recognising emotions)
• the study of Phineas Gage

  - had a iron metal rod blast through his left cheekbone and out through the top of his head

  - immediately after he was conscious and could speak, although he changed psychologically; following the accident he exhibited unreliable, quick-tempered, hostile and sexually inappropriate behaviour

  - the damaged area is thought to be responsible for functions such as planning, reasoning and control
• outline the case of E.B.

  had his left hemisphere removed at age 2.5, regained most of his language abilities

  at age 17, his language appeared almost normal in everyday life in terms of vocabulary and grammar
• area V1 / blindsight

  individuals with damage to Area V1 show ‘blindsight’

  individuals appear qualitatively blind, in that they report no vision, but they can locate objects in a visual field by pointing at them
• regions of the brain