Localisation of function in the brain Flashcards
What did Broca & Wernicke discover in the 19th century?
Specific areas of the brain are associated with particular physical and psychological functions
What was the holistic theory of the brain that scientists generally supported before investigations?
All parts of the brain were involved in the processing of thought and action
What did Broca & Wernicke argue?
The idea that different parts of the brain perform different tasks involved with different parts of the body
What are the 2 hemispheres of the brain?
Right & left hemisphere
What is lateralisation?
Our physical & psychological functions are dominated by a particular hemisphere
What is the corpus callosum?
Large bundle of more than 200 million nerve fibers that connects the 2 hemispheres & permits communication between them
What does the right & left hemisphere generally control?
- Right controls left side of the body
- Left controls right side of the body
What is the cerebral cortex?
Outer layer of both hemispheres and is what separates us from animals since it’s more developed in humans
What are the 4 lobes of the cortex of the hemispheres?
Frontal, parietal, occipital & temporal
What is the frontal lobe?
- back of frontal lobe is motor area
- controls voluntary movements
- location for awareness of what we’re doing within the environment
What is the parietal lobe?
- front of both parietal lobes is somatosensory area
- amount of somatosensory area devoted to body part denotes its sensitivity
- location for sensory & motor movements
What is the occipital lobe?
- visual area
- location for vision
What is the temporal lobe?
- auditory area which analyses speech-based info
- location for memory & auditory ability
What is restricted in only the left hemisphere of the brain?
Language
What did Paul Broca identify in the 1880s?
A small area in the left frontal lobe is responsible for speech production
What causes Broca’s aphasia?
Damage to Broca’s area which results in slow speech that lacks fluency
What was Wernicke identifying in patients?
They had no trouble producing language but had difficulty understanding it - speech was fluent but meaningless
What did Wernicke identify?
A region in the left frontal lobe that is responsible for language comprehension
What is Wernicke’s aphasia?
Damage to Wernicke’s area that results in patients producing nonsense words (neologisms) as part of their speech
Evaluation: Brain scan evidence of localisation
- supports localisation theory
- Petersen et al used brain scans to demonstrate how Wernicke’s area was active during listening task & Broca’s area active during reading task
- large no. of sophisticated methods to study brain activity provide scientific evidence for localisation theory
Evaluation: Neurosurgical evidence
- neurosurgery first developed in 1950s and still used today for extreme cases of OCD & depression
- Dougherty et al reported on 44 people who had undergone cingulotomy - after 32 weeks at post-surgical follow up a third had met criteria for successful response to the surgery
-success of these procedures suggest symptoms & behaviours associated with serious mental disorders are localised
Evaluation: Case study evidence
- Phineas Gage case of neurological damage supports localisation theory
- but it is difficult to make meaningful generalisations from findings of a single individual
- conclusions drawn may depend on subjective interpretations of the researcher
Evaluation: Language localisation questioned
- lang may not be localised to Broca & Wernicke’s area
- review by Anthony & Pascale in 2016 found that only 2% of modern researchers think that lang in the brain is completely controlled by Broca & Wernicke’s area
- fMRI scans allow brain to be studied with more clarity
- language streams have been identified across cortex & thalamus
- localisation theory is contradicted
