Localisation

• What is the definition of localisation? The theory that specific areas of the brain are associated with particular physical and psychological functions. Before the 19th century, scientists took a holistic view of the brain.
• What is the function of the motor cortex? Located in the frontal lobe and is responsible for generation of voluntary motor movements.
• How does the motor cortex work? It is contralateral: each hemisphere controls the opposite side of the body. Different parts of the motor cortex control different parts of the body. These are arranged logically - the region that controls the foot is next to the region that controls the leg.
• What is the function of the somatasensory area? Located in the parietal lobe of both hemispheres, this is where sensory information from the skin (touch, heat, pressure) is represented. Over half of this area is allocated to receptors for our face and hands.
• How does the somatasensory area work? It is contralateral - the cortex on one side of the brain receives sensory info from the opposite side of the body.
• What is the function of the visual area? Located in the occipital lobe. Nerve impulses from the retina travel to areas of the brain via the optic nerve. The visual cortex contains different areas that process different types of visual info such as colour, shape and movement.
• How does the visual area work? It is contralateral - left visual field of both eyes to the right handside (and vice versa)
• What is the function of the auditory area? Located in the temporal lobe of both hemispheres. Sounds waves are converted into nerve impulses. There is evidence that people prefer to be told things in their right ear (and are more likely to do a favour if presented to right ear) - processed by left hemisphere.
• How does the auditory area work?


  Contralaterally
• Language area: Only thing processed in one hemisphere is language. Language is processed in the left hemisphere for most people. Language production - left frontal lobe. Language comprehension - left temporal lobe.
• What is Broca's area? Identified as a small area in the frontal lobe that is responsible for speech production (BP). Damage to this area leads to Broca's aphasia - speech is slow and not fluent. e.g. Broca's patient called 'tan' because that was all that he could say
• What is Wernicke's area? A small area of the left temporal lobe which was responsible for language comprehension. Damage to this area leads to Wernicke's aphasia where patients can produce language (it is fluent but meaningless)
• Strength of localisation (case studies): + there is support from case studies

  e.g. the research of Phineas Gage showed that damage to the frontal lobe could result in changes in mood and personality

  this supports the localisation of function because it indicates the frontal lobe might be responsible for mood or personality - demonstrating localisation of these abilities.

  H - case study - low population validity
• Strength of localisation (brain scans): + there is support from brain scanning studies

  e.g. Peterson (1988) used brain scans to demonstrate how Wenicke's area was active during a listening task and Broca's area was active during a reading task supporting their views on these areas.

  this is a strength because there is a wealth of evidence from these scanning studies providing support for the idea that many neurological functions are localised, particularly in relation to language and memory. Brain scans are an objective and scientific way of showing localisation of brain functions.
• Strength of localisation (neurosurgery procedures): + there is support from neurosurgery procedures

  e.g. Dougherty showed that modern procedures like the CINGULOTOMY are successful with some OCD patients (and involves damaging a specific part of the brain - the cingulate gyrus. this is a strength because it shows that if the surgery techniques can be used to reduce symptoms, it indicates that symptoms and behaviours associated with serious mental health disorders are localised.

  H- the surgery procedures aren't effective for everyone with OCD
• Limitation localisation (functions appear to not be localised): - evidence against as some functions appear not to be localised. e.g. the cognitive function of being able to learn. Lashley (1950) removed parts of rat brains that were being assessed on learning mazes. no one area in particular seemed to be important, learning seemed to require all parts of the cortex. This suggests that at least some of the higher cogntive functions like learning are not localised to specific areas but are dealt with more holistically. H - study conducted on animals - issues with extrapolation
• Limitation of localisation (plasticity): - evidence against localisation in the plasticity of the brain. e.g. it has been shown that stroke victims can recover from some of their lost abilities over time. This means that localisation of function is not set or determined. The brain can actually recover part of the lost functions and other areas can take on the functions of the damaged areas. H - doesn't mean the original ability wasn't localised