Localisation of function

• Localisation of function

  During the 19th century, as cognitive neuroscience took over as our leading paradigm in psychology, it was discovered that certain area of the brain held particular functions 

  This is localisation of function 

  Localisation: the theory that specific areas of the brain are associated with particular physical and psychological functions
• Cerebral cortex

  The top surface layer of the brain is called cerebral cortex

  MEMORY TIP:

  Cortex means bark - like tree bark

  Tree bark covers the trunk of the tree, much like how the cerebral cortex covers the cerebrum
• Cerebrum

  The cerebrum is the largest part of the brain in humans, which consists of two large cerebral hemispheres

  The brain is divided into two hemispheres: the left and the right

  Each hemisphere (side of the brain) is responsible for specific functions

  Extra info- Lateralisation: The dominance of one hemisphere of the brain for particular physical and psychological functions.
• Hemispheres

  The left and the right sides of the brain are very similar.  

  One difference however is the presence of the language areas, which are only found on the left hand side
• Broca's area = This is responsible for converting thought into speech
• Wernicke's Area = This plays an important role in understanding other people's speech and for producing speech which makes sense
• Damage to either of these areas would result in aphasia - inability (or impaired ability) to understand or produce speech
• Paul Broca & Broca’s area

  Broca’s area was discovered when Paul Broca had a patient ‘Tan’. 

  • Broca called him Tan because that was the one syllable this patient could express. Tan had an unusual disorder - he had been able to understand spoken language, but unable to speak, nor express his thoughts in writing. 

  He then studied 8 other patients whom all had similar language deficits, along with lesions in their left frontal hemisphere. He found that patients with damage to these areas in the right hem did not have the same problems.
• Carl Wernicke & Wernicke’s area

  His patients had lesions in their posterior portion of the left temporal lobe could speak but were unable to understand language
• The central core

  This regulates our most primitive and involuntary behaviours such as breathing, sleeping or sneezing. 

  It is also known as the brain stem. It includes structures such as the hypothalamus – in the midbrain; 

  It regulates eating and drinking as well as regulating the endocrine system in order to maintain homeostasis.

  Homeostasis: the process by which the body maintains a constant physiological state
• The limbic system

  This controls our emotions. 

  Around the central core of the brain, interconnected with hypothalamus, it contains structures such as the hippocampus; key roles in memory.
• The cerebrum

  This regulates our higher intellectual processes. 

  It has an outermost layer known as the cerebral cortex; appears grey because of the location of cell bodies (hence “grey-matter”).  

  Each of our sensory systems sends messages to and from this cerebral cortex.

  The cerebrum is made up of the left and right hemispheres which are connected by a bundle of fibres called the corpus callosum
• Frontal Lobe = Control thoughts, memory, planning, problem-solving, cognitive and social behaviours such as facial expressions. Comprises motor area and one language area (Broca)
• Parietal Lobe = Somatosensory area: Controls behaviour involving the senses (touch, body awareness, heat, pressure)
• Temporal Lobe = Location of the auditory area and the centre of memory acquisition. It also includes part of the language area (Wernicke)
• Occipital Lobe = Contains the visual area. Visual informations are processed such as colour, shape and distance.
• AO3 - Evaluation

  (+) Brain scan evidence

  There is a wealth of evidence providing support for the idea that many neurological functions are localised, particularly in relation to language and memory

  Peterson (1988) used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task, suggesting that these areas are involved in the processing of language information
• AO3 - Evaluation

  (+) Neurosurgical evidence

  This is by far the most extreme treatment as it involves the destruction of healthy brain tissue:

  • Lobotomy: removal of the brain tissue
  • Leucotomy: cutting the connections to a particular part of the brain

  Controversially, neurosurgery is still used today for treatment-resistant severe depressives and extreme cases of OCD. The success of these procedures strongly suggests that symptoms and behaviours associated with serious mental disorders are localized