Localisation of function Flashcards
What is localisation of function?
Different areas of the brain are responsible for specific behaviours, processes or activities (cortical specialisation)
What did Broca and Wernicke discover?
Specific areas of the brain
What did scientists believe about brain function?
Holistic theory- all parts of the brain are involved in the processing of thought and action
What is the cerebrum?
The main part of the brain
What is the cerebrum divided into?
- 2 symmetrical halves:
- Right and Left hemispheres
What controls activity on the left hand side of the body?
The right hemisphere
What controls activity on the right hand side of the body?
The left hemisphere
What is the cerebal cortex?
The outer layer of the brain’s hemispheres (3mm thick)
What is the cortex divided into?
4 centres/’lobes’ of the brain:
- The frontal lobe
- The occipital lobe
- The parietal lobe
- The temporal lobe
What is a lobe?
An organ that is separate from the others
Where is the motor area located?
The back of the frontal lobe
What is the function of the motor area?
Controls voluntary movement in the opposite side of the body
(Damage to motor lobe= loss of control over fine movements)
Where is the somatosensory area located?
The front of both of the parietal lobes
What is the function of the somatosensory area?
Sensory information from the skin is represented here
Where is the visual area located?
The occipital lobe
What is the function of the visual area?
Receives and processes visual information
(Each eye sends info from right visual field to left visual cortex)
Where is the auditory area located?
The temporal lobe
What is the function of the auditory area?
Analyses speech-based information
(Damage can produce partial hearing loss)
What are the 2 language centres of the brain?
- Broca’s area
- Wernicke’s area
What side of the brain is language limited to?
The left hand side
What is Broca’s area?
- Located in the left frontal lobe
- Responsible for speech production
- Damage can cause Broca’s aphasia (slow, laborious speech, lacks fluency)
What is Wernicke’s area?
- Located in the left temporal lobe
- Responsible for language understanding
- Damage can cause Wernicke’s apashia (produce nonsense words)
What are the strengths of localisation?
- Evidence from neurosurgery
- Evidence from brain scans
- Case study evidence
What are the limitations of localisation?
- Counter-evidence for localisation
- Language localisation questioned
Strength:
I- Evidence from neurosurgery
D- Neurosurgery treats some mental disorders, which target specific areas of the brain (e.g: cingulotomy- isolating cingulate gyrus Dougherty et al- report on 44 people with OCD who had undergone a cingulotomy 32 weeks later- 30%= successful, 14%= partial response
E- Success suggests behaviour associated with mental disorders may be localised
Strength:
I- Evidence from brain scans
D- Peterson et al 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. LTM review by Buckner and Peterson- semantic and episodic memory resides in different parts of prefrontal cortex
E- Objective methods for measuring brain activity have provided accurate scientific evidence that functions are localised
Limitation:
I- Counter-evidence for localisation
D- Lashey removed areas of the cortex (10-50%) in rats who learnt the route through a maze. No area was more important than any other. Learning process required every part of the cortex
E- Suggests higher cognitive processes (learning) are not localised but distributed in a more holistic way
Limitation:
I- Language localisation questioned
D- Dick and Tremblay found 2% of modern researchers believe language is controlled fully by Broca and Wernicke’s areas. Scanning technique advances mean neural processes can be studied with more clarity (fMRIs). Language function= holistically distributed in brain. Language streams= across the cortex (thalamus, right hemisphere)
E- Suggests language is organised holistically, contradiciting localisation
Evaluation extra:
I- Case studies
Strength: Phineas Gage- metal pole passed through his eye, into his skull- removed a portion of his left frontal lobe (responsible for planning, reasoning, control). His personality changed- he became rude and hostile. Supports localisation theory
Limitation: Hard to make meaningful generalisations from studies of one individual. Conclusions may depend on subjective interpretation of researchers. Case study evidence is low in validity
