Localisation of Function

• Localisation of function is the idea that certain functions (e.g. language, memory, etc.) have certain locations or areas within the brain.
• Localisation of brain function has been supported by recent neuroimaging studies and some early case studies like Phineas Gage.
• Phineas Gage, who in 1848 while working on a rail line, experienced a drastic accident in which a piece of iron went through his skull.
• Although Gage survived his accident, he did experience a change in personality, such as loss of inhibition and anger.
• The change in Phineas Gage provided evidence to support the theory of localisation of brain function.
• There are four key areas in the brain for functioning; motor area, somatosensory area, visual area and the auditory area.
• The motor area is located in the frontal lobe and is responsible for voluntary movements by sending signals to the muscles in the body.
• Hitzig & Fritsch (1870) first discovered that different muscles are coordinated by different areas of the motor cortex by electrically stimulating the motor area of dogs.
• The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain and temperature.
• Different parts of the somatosensory area receive messages from different locations of the body. This was mapped by Penfield (1959).
• Penfield (1959) created a homunculus which was a visual representation of the mapping of body space in the somatosensory cortex of the brain. Each part of the body representing the size of the area of cortex devoted to it, and the sensitivity of that region.
• Robertson (1995) found the somatosensory area of the brain to be highly adaptable, with blind Braille readers having larger areas in this part of the brain.
• At the back of the brain, in the occipital lobe is the visual area, which receives and processes visual information.
• Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right hemisphere.
• The visual area contains different parts that process different types of information including colour, shape or movement.
• The auditory area is located in the temporal lobe and is responsible for analysing and processing acoustic information.
• The primary auditory area is involved in processing simple features of sound, including volume, tempo and pitch.
• Dougherty et al (2002) offer evidence from neurosurgery that damage to the brain is linked to mental disorders like OCD.
• Dougherty et al (2002) suggests that behaviours associated with serious mental health conditions may be localised in the brain.
• Petersen et al (1988) used brain scans to show how Wernicke's area was active during a listening task and Broca's area during a reading task.
• Buckner & Petersen (1996) confirm that memories are localised in the brain.
• Lashley (1950) challenged the idea of brain lateralisation suggesting the brain works more holistically.
• Lashley (1950) removed parts of the brain of rats to see the effects on learning a maze. The brain required several parts of the cortex to function not just one.
• Dick & Tremblay (2016) suggest the language centres may not be as localised as first thought.
• Advancements in brain scanning means the brain can be seen in more detail than ever before.
• Lobes of the brain.