Localistation of function In the brain Flashcards
c (11 cards)
What was the original theory about brain function and how did Wernicke and Broca challenge it?
- Psychologists originally believed the brain worked holistically — all parts involved in thought and action processing.
- Wernicke and Broca suggested different parts correspond to different functions and body parts — this is localisation of brain function.
What is the cerebrum and what is lateralisation?
- The cerebrum is the main part of the brain, divided into left and right hemispheres.
- Some psychological and physical functions are dominated by one hemisphere — called lateralisation.
- Usually, left hemisphere controls right side of body, right hemisphere controls left. * Language is linked to the left hemisphere.
What is the cerebral cortex and how is it organised?
- The cerebral cortex is the outer layer of both hemispheres.
- It is subdivided into four lobes: frontal, parietal, occipital, and temporal.
- A lobe is a part of an organ that is separate in some way from the rest.
What are the functions of the frontal and parietal lobes?
- Frontal lobe: controls movement and higher processing; contains motor area at the back. Damage can cause loss of fine motor control.
- Parietal lobe: contains somatosensory area where sensory info from skin is represented. Sensitivity depends on size of area (e.g., face receptors cover over half of somatosensory area).
What are the functions of the occipital and temporal lobes?
- Occipital lobe: at the back of brain, contains visual area that processes visual info. Each eye sends info from right visual field to left cortex and vice versa; damage can cause blindness in opposite visual field.
- Temporal lobe: contains auditory area for hearing. Damage can cause partial hearing loss. Wernicke’s area (in temporal lobe) is important for language comprehension; damage causes Wernicke’s aphasia.
What is Broca’s aphasia and how was it discovered?
- Aphasia: loss of ability to produce or understand speech.
- Broca studied patient “Tan” who could only produce a few words. Post-mortem showed damage to frontal lobe (Broca’s area).
- Broca’s aphasia causes problems producing speech.
What is Wernicke’s aphasia and how was it discovered?
- Wernicke’s patients could produce speech but couldn’t understand it, producing nonsense speech.
- Brain scans showed damage in lateral frontal lobes (Wernicke’s area).
- Wernicke’s aphasia causes impaired language comprehension.
How does neurosurgery support localisation theory?
Point: Neurosurgery targets specific brain areas linked to mental disorders.
Evidence: Cingulotomy isolates the cingulate gyrus implicated in OCD. Dougherty et al. reported that, after 32 weeks post-surgery, 30% of 44 OCD patients met criteria for success, 14% partial response.
Explain: Success suggests behaviours linked to mental disorders may be localised to specific brain regions.
Link: This strengthens localisation by showing targeted brain areas can influence behaviour and symptoms.
How do brain scans provide scientific support for localisation?
Point: Brain scans objectively show distinct areas active during different tasks.
Evidence: Petersen et al. found Wernicke’s area active during listening, Broca’s area during reading. Buckner and Petersen’s review showed semantic and episodic memory stored in different prefrontal cortex parts.
Explain: Brain imaging provides clear scientific evidence for localisation by mapping mental processes to brain areas.
Link: This supports localisation theory with objective, replicable data from brain scans.
How does Lashley’s research challenge localisation theory?
Point: Lashley’s rat studies suggest learning involves the whole cortex, not localised areas.
Evidence: Removing different cortex parts in rats learning a maze did not highlight any area as more important; learning seemed distributed.
Explain: This implies higher cognitive functions like learning may be holistic, contradicting strict localisation.
Link: Lashley’s findings challenge localisation, suggesting some brain functions are more distributed.
Why might language not be strictly localised to Broca’s and Wernicke’s areas?
Point: Modern research shows language involves wider brain regions beyond Broca’s and Wernicke’s areas.
Evidence: Dick and Tremblay’s review found only 2% of researchers think language is solely controlled by those areas. fMRI shows language streams across cortex, including right hemisphere and subcortical areas like the thalamus.
Explain: Language appears to be organised holistically rather than confined to key areas.
Link: This undermines strict localisation and supports a more networked brain organisation for language.
