Localisation of Function
- Created by: hellostudents
- Created on: 31-03-20 12:20
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- Localisation of Function
- Visual and Auditory Centers
- Visual centres
- The primary visual centre is located in the visual cortex in the occipital lobe of the brain
- Visual processing starts in the retina - light hits the photoreceptors
- Nerve impulses from the retina are transmitted to the brain via the optic nerve
- Most terminate in the thalamus passing the information to the visual cortex
- Nerve impulses from the retina are transmitted to the brain via the optic nerve
- The visual cortex spans both hemispheres
- Right hemisphere receives input from the left side of the visual field
- Left hemisphere receives from the right hand side of the visual field
- Visual processing starts in the retina - light hits the photoreceptors
- The primary visual centre is located in the visual cortex in the occipital lobe of the brain
- Auditory centres
- Concerned with hearing
- Within the temporal lobes on both sides of the brain - auditory cortex
- Pathway begins in the cochlea (inner ear) where sound waves are converted into nerve impulses. Travels via the auditory nerve to the auditory cortex
- First stop on journey is the brain stem where basic decoding takes place
- Next stop is in the thalamus which acts as a relay station
- Last stop the auditory cortex sound is recognised and met with appropriate response
- Visual centres
- Motor and Somatosensory areas
- The Motor cortex
- Responsible for the generation of voluntary motor movement
- Located in the frontal lobe of the brain - precentral gyrus
- In both hemispheres of the brain to control muscles on opposite sides of the body
- The somatosensory cortex
- Detects sensory events arising from different regions of the body
- Located in the parietal lobe of the brain along the postcentral gyrus
- In both hemispheres
- The Motor cortex
- Language Centres
- Broca's area
- Paul Broca - treated 'Tan' (only syllable the patient could express)
- Tan can understand spoken language but was just unable to speak it or express thoughts in writing
- Broca also studied 8 other patients who had similar language deficits along with lesions in the left frontal hemisphere
- Damage in the right hemisphere did not have the same problem
- Led Broca to identify the language centre in the posterior in the frontal lobe in the left hemisphere
- Broca also studied 8 other patients who had similar language deficits along with lesions in the left frontal hemisphere
- Tan can understand spoken language but was just unable to speak it or express thoughts in writing
- Fedorenko - discovered 2 parts of Brocas area (1 involved with language an the other involved in responding to demanding task)
- Paul Broca - treated 'Tan' (only syllable the patient could express)
- Werinicke's area
- Involved in understandinglanguage
- Patients with damage in this area could speak but where unable to understand language
- Wernicke proposed that language involves separate motor and sensory regions located in different cortical regions
- Found in the posterior of the left temporal lobe
- Involved in understandinglanguage
- There is a neutral loop called the accurate fascicles running between these 2 areas
- Broca's area
- Evaluation
- Individual differences in language areas
- The pattern of action observed in response to language activities vary from person to person
- Study of silent reading by Bavelier in 1997 found a large variability in individual patterns of activation across different individuals
- They observed activity in the right temporal lobe as well as the left frontal, temporal and occipital lobes
- Other studies have found significant gender differences in the size of the areas associated with language
- Harasty - found women have larger Brocas and wernickes areas than men
- Study of silent reading by Bavelier in 1997 found a large variability in individual patterns of activation across different individuals
- The pattern of action observed in response to language activities vary from person to person
- Language production may not be confined to Broca's area alone
- Dronker's re-examined the preserved brains of Broca's patients (Tan)
- This was to identify the extent of any lesions in more detail by using modern high-resolution MRI imaging
- These findings revealed that other areas besides Broca's area could have contributed to reduced speech abilities
- These findings are significant because although lesions to Broca's area alone can cause temporary speech disruption
- The study suggests that language and cognition are more complicated and involve networks of brain regions rather than localised to specific areas
- These findings revealed that other areas besides Broca's area could have contributed to reduced speech abilities
- This was to identify the extent of any lesions in more detail by using modern high-resolution MRI imaging
- Dronker's re-examined the preserved brains of Broca's patients (Tan)
- Support for language centres from aphasia studies
- Aphasia is refers to the inability to understand or produce speech as a result of brain damage
- In most cases the Brian damage is in Broca's area this demonstrates the important role of Broca's area in the production of language
- Aphasia is refers to the inability to understand or produce speech as a result of brain damage
- Communication may be more important than localisation
- Wernicke claimed that although different regions of the brain has different specialist functions that are independent in the sense that in order to work they must interact
- This suggests that complex behaviours such as language, reading and movement are built up gradually as a stimulus enters the brain
- Damage to the connection between any 2 points in the process results in impairments that resemble the damage to the localised brain region associated with a function
- This suggests that complex behaviours such as language, reading and movement are built up gradually as a stimulus enters the brain
- Wernicke claimed that although different regions of the brain has different specialist functions that are independent in the sense that in order to work they must interact
- Challenges to localisation: Equipotentiality
- Equipotentiality theory by Lashley in 1930 - basic motor and sensory functions were localised , but higher mental functions were not
- Lashley claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following injury to the area normally responsible
- The effects of damage to the brain would be determined by the extent rather than the location of the damage
- Lashley claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following injury to the area normally responsible
- Equipotentiality theory by Lashley in 1930 - basic motor and sensory functions were localised , but higher mental functions were not
- Individual differences in language areas
- Visual and Auditory Centers
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