localisation

• localisation


  The different parts of the brain are responsible for different functions
• holistic theory


  All the parts of the brain are involved in the processing of thought and action.

  
  

  This was dominant before the 19th century
• Paul Broca and Karl Wernicke argued


  They argued for the localisation of function in which different parts of the brain perform different tasks and are involved with different parts of the body.

  If that area is damaged the function will also be damaged
• What are the 2 hemispheres of the brain?

  The activity on the left side of the body is controlled by the right hemisphere and activity on the right side of the body is controlled by the left hemisphere
• What is the outer layer of each hemisphere called?

  - Cerebral cortex and it is 3mm thick.

  - It separates us from other animals

  - The cortex is grey
• motor area


  - Located at the back of the frontal lobe

  - Controls voluntary movement on the opposite side of the body

  - Damage may result in loss of control over fine movements
• somatosensory area


  - Located in the front of the parietal lobes

  - Separated from the motor area by the central sulcus

  - Sensory information from the skin is represented

  - The more sensitive the area, the more space is devoted
• visual area


  - Located in the occipital lobe

  - Each eye sends information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex

  - Damage to the left hemisphere can produce blindness in part of the right visual fields of both eyes
• auditory area


  - Located in the temporal lobes

  - Analyses speech-based information

  - Damage could cause partial hearing loss

  - Damage to specific areas (Wernicke's area) may affect the ability to understand language
• Broca's Area


  - Restricted to the left side

  - 1880s - Paul Broca identified a small area in the frontal lobe which was responsible for speech

  - Damage causes Brocasphasia (slow speech)
• Wernicke's Area


  - Restricted to the left side

  - 1880s - Karl Wernicke identified an area in the temporal lobe that was responsible for language comprehension

  - Damage causes Wernickesphasia (nonsense words - can speak but can't understand language)
• AO3 = Brain Scan Evidence (strength)

  Peterson et al (1988) - used brain scans which showed that Wernicke's area was active during a listening task and Broca's area was active during a reading task

  
  

  Tulving et al (1994) - stated that semantic and episodic memories are stored in different parts of the prefrontal cortex
• AO3 = Neurosurgical Evidence (strength)

  Lobotomy - the practice of surgically removing areas of the brain to control behaviour developed by Walter Freeman in the 50s

  - Early attempts. involved severing connections in the frontal lobe to try and control aggression

  Neurosurgery - used today to treat extreme cases of OCD & Depression

  
  

  - Dougherty et al (2002) = 44 OCD patients had a cingulotomy, the follow-up after 32 weeks showed that 1/3 had a successful response to the surgery.
• AO3 = Case Study Evidence (strength)

  Phineas Gage - suffered damage to his left frontal lobe which caused a personality change in him as he changed from calm & reserved to quick-tempered and rude
• AO3 = Case Study Evidence (weakness)

  It lacks population validity as there were only a couple of reports.
• AO3 = Lashley's Research (weakness)


  Karl Lashley (1950) suggested that higher cognitive functions are not localised but spread in a more holistic way.

  
  

  He removed between 10%-50% of the cortex in rats who were learning a maze. This found that no area was more important than any other in the rat's ability to learn.
• AO3 = Plasticity (weakness)


  - When the brain is damaged and function is lost the rest of the brain reorganises itself in an attempt to recover the lost function (Law of Equipotentiality)

  
  

  - It suggests that all parts of the brain can perform all functions