Localisation of Function Flashcards
What is meant by localisation of function?
The idea that different areas of the brain are responsible for specific behaviours, processes or activities.
Where are Brocas and Wernickes areas found in the brain?
They are only in the left hemisphere.
What is meant by the term Hemispheric Lateralisation?
Each hemisphere is specialsed to perform different functions.
E.g Language centres in the left hemisphere whereas visualspatial tasks are best performed in the right.
What is meant by Contralateral?
Each hemisphere of the brain controls the opposite side of the body, this includes both motor and visual pathways.
Where is the Visual cortex found, and what is its role?
Occipital Lobe
- Recieves and processes visual information.
- Info is recieved from the contralateral visual field. E.g LH processes what is seen by the right eye.
Where is the Motor Cortex found, and what is its role?
Back of the frontal lobe (Both HMSPHR)
- Controls voluntary movement in the opposite side of the body
Where is the Somatosensory cortex found, and what is its role?
Front of the parietal lobe
It is divided from the motor area via a fold called the central sulcus
- processes sensory information such as touch
Where is the Auditory cortex found, and what is its role?
Temporal lobe
- Recieved auditory and sound sensation from the ears
Where is the Brocas area found, and what is its role?
Left frontal lobe (LH only)
- Responsible for speech production
What does damage to the Brocas area cause?
Aphasia, difficulty in producing fluent speech, it is slow and labourious.
Where is the Wernickes area found, and what is its role?
Top temporal lobe
- Responsible for speech comprehension.
What does damage to the Wernickes area cause?
Wernickes Aphasia, difficulty understanding speech, and producing speech that lacks meaning.
What is global aphasia?
Damage to both Wernickes and Brocas area, leads to the inabilit to produce or understand speech.
Who did Broca study?
Patient called Tan.
- Tan was only able to say the word Tan, even though he could understand speech.
+EV 1: Evidence from Brain scans
- Brain scans support the idea that brain function is localised.
- Peterson (1988) used brain scans to demonstrate how the Wernickes area was active during a listening task, and the Brocas area was active during a reading task.
- Also a study of LTM by Tulving (1994) revealed that semantic and episodic memories reside in different areas of the prefrontal cortex.
- These studies confirm that areas are localised for everyday behaviours.
- Therefore objective methods used to measure brain activity have provided sound scientific evidence that many brain functions are localised.
-EV 2: Language may not just be localised to Brocas and Wernickes area.
-A recent review by Dick (2016) found that only 2% of modern reseacher think that the brain is completely controlled by these areas.
-Advances in brain imaging techniques such as FMRI mean that neural processes in the brain can be studied with more clarity then ever before.
-These have revealed that language function is distributed more holistically in the brain, language streams have been found across the cortex, right hemisphere and subcortical areas like the thalamus.
-This suggests that rather than language being confined in certain areas of the brain, it may be more holistic, which contradicts localisation theory.
-EV 3: Lashley rat experiment
- Lashley (1950) had removed the cortexs of rats.
- The rats ablility 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 region.
