- Brain is divided into 2 halves- left and right hemisphere
- Lateralisation: some physical and psychological functions are controlled by a particular hemisphere
- Generally, the left side of the body is controlled by the right hemisphere and the right the left
- Cerebral cortex: like a ‘tea cosy’ covering the inner parts of the brain, is what separates us from lower animals as it is highly developed- appears grey hence grey matter
- Cortex of both hemispheres is divided into 4 loves (frontal, parietal, occipital and temporal)
- Motor area: controls voluntary movement- damage may result in loss of control over fine motor movements (frontal lobe)
- Somatosensory area: (parietal lobe) processes sensory information from the skin (touch, heat etc)
- Visual area: (occipital lobe) each eye sends info from the right visual field to the left visual cortex
- Auditory area: (temporal lobe) analyses speech-based information- damage may produce partial hearing loss
- Broca’s area: speech production- left frontal lobe- damage to this area causes Broca’s aphasia- slow, laborious speech lacking in fluency- difficulty naming certain objects- difficulties with prepositions and conjunctions- discovered by Broca 1880s
- Wernicke’s area: language comprehension- back of temporal lobe- discovered by Wernicke in 1880s- patients produce language but have problems understanding it- produce fluent but meaningless speech- patients with Wernicke’s aphasia will often produce nonce words (neologisms)
- Discuss localisation of function in the human brain (AO1)In the brain the cortex of both hemispheres is divided into four lobes: frontal, parietal, occipital and temporal. At the back of the frontal lobe is the motor area. The motor area controls voluntary movement by sending signals to the muscles, damage of this area may result in loss of control over fine motor movements. At the front of the parietal lobes is the somatosensory area. This area processes sensory information from the skin (touch, heat, pressure etc). In the occipital lobe is the visual area which receives and processes visual information. Information from the right visual field is processed in the left hemisphere, and information from the left visual field is processed in the right hemisphere. The visual area contains different parts that process different types of information including colour, shape or movement. In the temporal lobe is the auditory area which analyses speech-based information. Damage may produce partial hearing loss. There is also Broca’s area which is involved in speech production. damage to this area causes Broca’s aphasia: slow, laborious speech lacking in fluency as well as difficulty naming certain objects and difficulties with prepositions and conjunctions. There is also Wernicke’s area which is involved with language comprehension. patients produce language but have problems understanding it- produce fluent but meaningless speech- patients with Wernicke’s aphasia will often produce nonce words (neologisms).
A03
- Strength- supporting evidence
- Peterson et al used brain scans to show activity in Wernicke’s area during a listening task and in Broca’s area during a reading task- suggesting these areas of the brains have different functions
- Tulving et al- revealed semantic and episodic memories are located in different parts of the frontal cortex
- Now there exists a number of sophisticated and objective methods for measuring activity in the brain, providing sound scientific evidence of localisation of function
- Strength- support from neurological evidence
- Dougherty et al reported on 44 OCD patients who had a cingulotomy
- At a 32-week follow-up, one third met the criteria for successful response to surgery and 14% a partial response
- The success of such procedures strongly suggests that symptoms and behaviours associated with serious mental disorders are localised
- Limitation- doesn’t take into account individual differences
- Herasty found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women
- This, however, suggests a level of beta bias in the theory: the differences between men and woman are ignored, and variations in the pattern of activation and the size of areas observed during various language activities are not considered
- Limitation- contradictory research
- The work of Lashley suggest higher cognitive functions (e.g. learning processes) are not localised but distributed in a more holistic way in the brain
- Lashley removed between 10 and 50% of the cortex in rats that were learning a maze
- No area was proven to be more important than any other in terms of the rat’s ability to learn the maze
- The process of learning appeared to require every part of the cortex- rather than being confined to one area
- Suggests learning is too complex to be localised
- However, rats are not humans
PHINEAS GAGE
- Strength- supporting evidence
