Localisation of Function in the Brain (AQA A Level Psychology)

Localisation of function in the brain

• Localisation of brain function (LOF) is the theory that specific functions/processes are localised to/can be found in specific locations in the brain e.g.

  • the hippocampus has been strongly implicated in the processing of memory

  • the pre-frontal cortex has been linked to impulse control and executive functioning

• The theory challenges and refutes previous assumptions that the brain is unimodal

• LOF can be measured using brain-imaging techniques such as

  • MRI

  • fMRI

  • PET

Lobes of the brain

• The brain is divided into two hemispheres, left and right and is covered by a thin layer known as the cerebral cortex

• As each hemisphere is responsible for different functions then each lobe is responsible for specific functions located within that lobe

• The frontal lobe and some associated areas and functions: 

  • the motor cortex is responsible for movement

  • the prefrontal cortex is responsible for executive functioning

  • Broca's area is responsible for speech production

• The temporal lobe and some associated areas and functions: 

  • the auditory area is responsible for auditory processing e.g. hearing

  • Wernicke's area is responsible for language comprehension 

  • The hippocampus is responsible for memory and spatial navigation

• The parietal lobe and some associated areas and functions: 

  • the somatosensory cortex is responsible for touch sensation e.g. heat, pain

  • the parietal lobe governs body orientation e.g. understanding whether an object is on the right or the left of you

  • the parietal lobe aids learning in the practice of complex, precise movements e.g. writing

• The occipital lobe

  • the visual area is responsible for the processing of visual information e.g. sight

  • the visual area aids in understanding distance and depth perception

  • the visual area aids in the recognition of objects and faces

• The brain also includes

  • the cerebellum which controls balance and coordination

  • the brain stem which controls involuntary responses

Evaluation of localisation of function in the brain

Strengths

• There is robust evidence to support the idea of LOF e.g.

  • Maguire et al. (2000)

    • Spatial navigation is localised to the posterior hippocampus via analysis of MRI scans

  • The case of Phineas Gage (Harlow, 1848)

    • Linked personality changes to damage in the frontal lobe caused by an iron bar shooting through his eye socket and out through the top of his skull

  • Petersen et al.(1988)

    • PET scans showed that Broca's area is active when reading; Wernicke's area is active when listening

• The techniques used to find supporting evidence for LOF are objective and clinical

  • This means that the procedure can be replicated to check for consistency

  • Therefore these techniques are high in reliability

Limitations

• The biggest criticism of LOF was presented by Lashley (1950), who researched rats which had parts of their cortex removed

  • The rats' ability to navigate and memorise routes through a maze did not appear to correspond with any specific brain region

  • Lashley concluded that cognitive functions are shared across the cortex holistically rather than being localised to one structure/region

• Lashley also suggested the law of equipotentiality as a challenge to LOF

  • This law states that when one part of the brain (specifically the cerebral cortex) is damaged, another part or region can take over

  • Research into neuroplasticity supports this