Localisation, laterlisation and holism Flashcards
What is localisation?
The theory that specific areas of the brain are associated with particular physical and psychological functions.
What is lateralisation?
One hemisphere of the brain being responsible for particular physical and psychological functions.
How is sensory processing and motor control housed?
Contralaterally (opposite side)
So damage to the left hemisphere will affect the right side of the body. Also, language for most people is based only in the left hemisphere.
The cerebrum is made up of the left and right hemispheres connected by the corpus callosum.
Who was Phineas Gage?
Had an iron rod shot through his brain and lived for 12 more years.
He became challenging, impatient and rude; reportedly ‘not Gage’.
His frontal loves were damaged - we now know that this area is associated with impulse control and mood regulation.
What evidence is there for localisation?
Petersen et al
- Brain scans of people doing a listening task and a reading task
- Wernicke’s area was more active during a listening task and Broca’s was more active during a reading task.
- Supports localisation of function
Tulving et al
- Carried out brain scans (PET) to show images of the brain while participants recalled different types of memories
- They located different sections of the pre-frontal cortex for (left) semantic and (right) episodic memorie
What neurosurgical evidence for localisation is there?
From 1950s onwards brutal and imprecise lobotomies were performed as treatments.
The frontal lobes were servered form the brain with devastating effects, including personality changes and losing the ‘self’.
This supports localisation of function.
What evidence is there for holistic brain function?
Lashley (1950)
Removed parts of the cortex (10-50%) in rats who were learning a maze.
He found that maze learning was not housed in a particular part of the cortex - this ‘higher level’ task was distributed across the brain.
This argues against localisation.
However, the research is done on rats, they are different species who don’t have the same cognitive abilities as humans, so can’t be generalised to humans.
What is the holistic theory of brain function?
The theory that the brain works as one, with no area more or less responsible for any function.
This is no longer an accepted theory - we have very good evidence of localisation of function - that certain functions take place in specific areas of the brain.
However, the brain’s remarkable ability to recover from trauma and its plasticity tell us that functioning is not necessarily always limited to a specific area of the brain.
