localisation of function in the brain

• what is lateralisation?

  the idea that one half of the brain is responsible for carrying out a specific job
• how is the brain divided?

  two halves (right hemisphere and left hemisphere)
• what is the corpus callosum?

  a bundle of nerve axons which connect the two hemispheres which allows them to communicate with each other
• what is localisation?

  the idea that a specific area of the brain is responsible for carrying out a specific job
• what does the holistic theory propose about brain function?

  the idea that all parts of the brain were involved in the processing of thought and action
• how was the holistic theory of brain function disproved?

  the case study of phineas gage and the work of broca, wernicke and tulving all showed that different parts of the brain perform different functions and if one becomes damaged, the jobs done by that area will be affected
• what is the cerebral cortex and its function?

  the outer layer of the brain which is where information is processed
• what is the cerebral cortex made of?

  grey matter which are made up of cell bodies
• why is the cerebral cortex folded?

  so it has a large surface area to allow more neurones
• what are the cortex of both hemispheres divided into?

  four lobes
• what are the four lobes of the brain?

  temporal

  frontal

  parietal

  occipital
• what is the function of the temporal lobe?

  analyses speech-based information
• what happens when the temporal lobe part of the brain is damaged?

  could produce hearing loss - the more widespread the damage, the more serious the hearing loss
• what is the function of the frontal lobe?

  contains the motor cortex (back of the frontal lobes) which is responsible for producing voluntary motor movements, the motor cortex on one side of the brain controls muscles on opposite side of the body
• what happens when the frontal lobe part of the brain is damaged?

  could result in loss of fine control over movement
• what is the function of the parietal lobe?

  contains the somatosensory cortex (front of the parietal lobes) which processes sensory info from the skin (touch, pain etc.) and the somatosensory cortex on one side of the brain processes sensory info on opposite side of the body
• what happens when the parietal lobe part of the brain is damaged?

  could disrupt a person's ability to understand spoken and/or written language
• what is the function of the occipital lobe?

  contains the visual cortex (back of the occipital lobes) where right hemisphere receives input from the left visual field (light from left of body hits right side of both eyes) and the left hemisphere receives its input from the right visual field (light from right of body hits left part of each eye)
• what happens when the occipital lobe part of the brain is damaged?

  could result in blindness in the left visual field of both eyes
• what is the optic chiasm?

  the point at which the optic nerves from the nasal side cross
• where is the left visual field?

  right hemisphere (anywhere to the left of your nose)
• where is broca's area located?

  left frontal lobe only
• what is the function of broca's area?

  speech production (movement of lips etc.)
• what happens when broca's area is damaged?

  broca's aphasia
• what is broca's aphasia characterised by?

  slow, laborious speech which is lacking in fluency and could find it difficult naming certain objects
• what was the aim of broca's study with tan?

  to identify the neural basis of tans's language system
• what was the procedure of broca's study with tan?

  post mortum
• what were the results of broca's study with tan?

  found that the motor cortex of the frontal lobe was damaged
• what was the conclusion of broca's study with tan?

  tan understood spoken language but couldn't speak/express thoughts in writing - broca found that tan and 8 patients with similar language problems suffered damage to their left frontal hemisphere. patients with damage to right frontal hemisphere didn't have the same problems. broca concluded that a language centre is present in the back of the frontal lobe of the left hemisphere, which is critical for speech production
• where is wernicke's area located?

  front temporal lobe in the left hemisphere
• what is the function of wernicke's area?

  speech comprehension (understanding/choosing correct words and processes language)
• what happens when wernicke's area is damaged?

  people can produce sentences but they tend to be meaningless/jumbled up/nonsense words
• what is the law of equipotentiality and how does it relate to localisation of function in the brain?

  every part of the brain has equal potential to carry out every task (whereas localisation suggests particular parts of the brain are responsible for particular jobs)
• what is a positive evaluation point for localisation of function in the brain?

  scientific research evidence - tulving et al (1994) used brain scans to show that semantic/episodic memory are located in

  different parts of the frontal cortex + peterson et al (1988) used brain scans to show wernicke's area was active during a

  listening task and Broca's area was active during a reading task (these areas have two

  different functions) so its a valid concept

  case studies - phineas gage lost a piece of his frontal lobe when a metal rod was blasted

  out of the top of his skull. his personality changed from calm to quick-tempered, rude and 'no longer Gage'

  so the frontal lobes may be responsible for mood + personality
• what is a negative evaluation point for localisation of function in the brain?

  contradictory research to suggest complex activities involve the entire brain - lashley removed 10-50% of brain of rats learning a maze. no one area was more important than another in the rats' ability to learn it, they were equally as disabled so the theory may lack validity

  challenged by neural plasticity - stroke victims regain abilities they lost due to it (law of equipotentiality) so the theory may lack validity