Localisation of function Flashcards
what is localisation of function?
Localisation of function- the theory that different areas of the brain are responsible for specific behaviours, processes or activities.
what is the difference between localisation and a holistic theory?
- During 19th century Broca and Wernicke discovered that specific areas of the brain are associated with particular physical and psychological functions.
- Before this scientists generally supported a holistic theory of the brain, that all parts of the brain were involved in the processing of thought and action.
- Broca and Wernicke argues for the localisation of function, that different parts of the brain preform different tasks.
- If a certain area of the brain is damaged through illness or injury, the function associated with that area will also be affected.
what are the different hemispheres of the brain?
- Cerebrum is divided into two symmetrical halves called the left and right hemisphere.
- Some of our physical and psychological functions are dominated by a particular hemisphere, this is called lateralisation.
- Left hand side of the body is controlled by the right hemisphere and right hand side of the body controlled by left hemisphere.
- Language is also linked to the left hemisphere.
what are the four centres that divide the cerebral cortex?
- The cerebral cortex is subdivided into 4 centres called the lobes of the brain.
- These include the frontal lobe, parietal lobe, occipital lobe and the temporal lobe.
- Each lobe is associated with different function.
what does the frontal lobe control?
At the back of the frontal lobe is the motor area, this controls voluntary movement on the opposite side of the body. Damage to this area may result in a loss of control over fine movements.
what does the parietal lobe control?
• At front of both parietal lobes is the somatosensory area, this is where sensory information from the skin is represented.
what does the occipital lobe control?
• In the occipital lobe at the back of the brain is the visual area, each eye sends information from right visual field to the left visual cortex and vice versa. Damage to the left hemisphere could produce blindness in the right eye.
what does the temporal lobe control?
• Temporal lobe is the auditory area, this analyses speech based information and damage to it could produce hearing loss. Damage to Wernicke’s area may affect the brains ability to comprehend language.
where are the language centres of the brain?
- Language is restricted to the left side of the brain for most people.
- Broca identified a small area in the left frontal lobe responsible for speech production, damage to Broca’s area causes Broca’s Aphasia. It is characterised by slow speech and lacking in fluency.
- People with Broca’s aphasia also have difficulty with prepositions and conjunctions.
- Wernicke identified a region in the left temporal lobe as being responsible for language understanding, when this area was damaged it results in Wernicke’s aphasia.
- People with Wernicke’s aphasia will often produce nonsense words as part of the content fo their speech. Have difficult comprehending language.
what evidence provides support for the localisation theory?
- One strength of localisation theory is that damage to areas of the brain has been linked to mental disorders.
- Cingulotomy involves isolating a region called the cingulate gyrus which has been implicated in OCD.
- Dougherty et al reported on 44 people with OCD that had undergone cingulotomy. At post surgical follow-up after 32 weeks 30% had met the criteria responsible for successful response and 14% for a partial response.
- Success of these procedures suggests that behaviour associated with serious mental disorders may be localised.
what other evidence supports localisation?
• Another strength is evidence from brain scans which supports the idea that many everyday brain functions are localised.
• Petersen 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. A review of long-term memory studies by Buckner and Petersen revealed that semantic and episodic memories reside in different parts of the prefrontal cortex.
These studies confirm localised areas for everyday behaviours.
what is a counterpoint to Peterson’s brain scans?
- Lashley removed areas of the cortex in rats that were learning the route through a maze.
- No area was proven to be more important than any other area in terms of the rat’s ability to learn the route. The process of learning seemed to require every part of the cortex rather than being confined to a particular area.
- Suggests that higher cognitive processes, such as learning, are not localised but distributed in a more holistic way in the brain.
