Localisation of function in the brain

• Define localisation of function in the brain.

  Localisation of function in the brain refers to the proposal that there are certain areas of the brain that are responsible for specific functions. For example, the pre-frontal cortex is proposed to play a big role in decision making.
• Outline localisation of function in the motor cortex.

  The motor cortex is located in the frontal lobes of both hemispheres. It is responsible for voluntary motor movements. It is highly localised in that different areas of the motor cortex control movement of different areas of the body. This means that damage to the motor cortex could impair voluntary muscle movement, sometimes in specific areas of the body.
• Outline localisation of function in the somatosensory cortex.

  The somatosensory cortex is located in the parietal lobes of both hemispheres. It is responsible for processing touch sensations such as pressure, pain and temperature. It is highly localised in that different areas of the somatosensory cortex process touch sensations from different areas of the body. This means that damage to the somatosensory cortex could impair touch sensations, sometimes in specific areas of the body.
• Outline localisation of function in the auditory cortex.

  The auditory cortex is located in the temporal lobes of both hemispheres. It is responsible for processing auditory (sound-based) information. This means that damage to the auditory cortex could impair auditory perception, potentially leading to complete deafness despite normally functioning ears.
• Outline localisation of function in the visual cortex.

  The visual cortex is located in the occipital lobes of both hemispheres. It is responsible for processing visual information. This means that damage to the visual cortex could impair visual perception, potentially leading to complete blindness despite normally functioning eyes.
• Outline the localisation of function of Broca’s area.

  Broca’s area is located in the left frontal lobe. It is responsible for speech production. This means that damage to Broca’s area could result in difficulties producing speech whereby the individual can only talk in short sentences which take great effort. They may also struggle to produce certain words, particularly linking words such as ‘and’.
• Outline the localisation of function of Wernicke’s area.

  Wernicke’s area is located in the left temporal lobe. It is responsible for language comprehension. This means that damage to Wernicke’s area could result in difficulties understanding language. This can result in the individual being able to speak fluently but making little sense.
• A strength of localisation of function in the brain - received SE from post-mortem examinations.

  Broca conducted a post-mortem on a patient who had experienced speech production difficulties in their lifetime- found damage to Broca’s area. Wernicke conducted a post-mortem on a patient who had experienced language comprehension difficulties in their lifetime and found damage to Wernicke’s area. strength - supports the proposal that there are different areas of the brain that are responsible for different functions damage to these areas can result in the impaired functioning of their roles.
• A limitation is that supporting evidence through post-mortem examinations cannot establish cause and effect.

  This is because any damage found in the brain may be due to the natural decay of the brain after death. This is a limitation because it means the damage may be unrelated to the difficulties the individual experienced in their lifetime and so that brain area may be unrelated to that function. Therefore questions credibility.
• strength of localisation of function in the brain is that it has received further supporting evidence from brain scanning studies.

  E.g. fMRI research has found that Broca’s area is highly active during speaking aloud tasks while Wernicke’s area is highly active during language comprehension tasks. This is a strength because it supports the proposal that there are different areas of the brain responsible for different functions (i.e. Broca’s area for speech production and Wernicke’s area for language comprehension).
•  limitation of localisation of function in the brain is that it has received opposing evidence.

  E.g. a researcher found that a patient who had damaged their Broca’s area and so experienced speech production difficulties later developed the ability to speak using an area of their right hemisphere. This is a limitation because it suggests that while brain areas may initially be dominant for a function, they are not specialised for it. Instead, other brain areas can take over this function if it were to become damaged. Therefore questions credibility.
•  limitation of localisation of function in the brain - too reductionist.

  researcher found that making lesions to specific areas of rats’ brains did not impair their ability to solve a maze. their performance was only affected when there was widespread damage to their brain. limitation - it suggests that higher-order cognitive processes such as learning involve multiple brain areas. some psychologists argue that it is more important to investigate how brain areas communicate with one another in a more holistic fashion rather than focusing on individual brain areas in isolation. ? cred.
• One way in which researchers have studied localisation of function in the brain

  Researchers have studied localisation of function in the brain using post-mortem examinations. This involves carrying out a physical examination of the brain of a patient who showed abnormal behaviours when alive. The aim is to assess whether there is any damage to any specific areas of the brain that could have caused the abnormalities they experienced in their lifetime. If there is damage to a specific area, it is assumed that the area plays a role in that function.
• brain scanning techniques to study localisation of function in the brain

  Another way researchers have studied localisation of function in the brain is by using brain scanning techniques such as fMRI. This involves scanning an individual’s brain whilst they complete a given task. The aim is to assess whether there is increased activity in any specific brain areas during the task. If there is, that brain area is assumed to play a role in that task.
• researchers have studied localisation of function in the brain is through animal lesion studies.

  This involves cutting a specific area of an animal’s brain and then assessing how it affects their behaviour/performance in a task. If it results in any abnormal behaviour (e.g. increased aggression) that brain area is assumed to be responsible for that function.
• limitation of post-mortem examinations as used to investigate localisation of function in the brain is that they cannot establish cause and effect.

  This is because any damage found in the brain may be due to the natural decay of the brain after death. This is a limitation because it means the damage may be unrelated to the difficulties the individual experienced in their lifetime and so that brain area may be unrelated to that function. Therefore questions credibility.
•  strength of fMRI as used to investigate localisation of function in the brain is that it has high spatial resolution.

  This is because it can accurately detect the location of brain activity to within 1mm. This is a strength as it means that the research is able to pinpoint what specific areas of the brain are active during a specific task.
•  limitation of fMRI as used to investigate localisation of function in the brain is that it has low temporal resolution.

  This is because there is a time delay between when the brain is active and when the fMRI machine is able to detect the activity. This is a limitation because it can make it difficult to assess whether observed brain activity is related to the current task or not and, as a result, whether the brain area is responsible for that function. Therefore questions credibility.
• limitation is that some methods of studying localisation of function in the brain have relied upon animals.

  E.g. lesion studies have typically involved rats. This is a limitation because the findings from these studies may not generalise to human brains which are typically more complex and work in a more holistic fashion. Therefore questions credibility.