Localisation of function Flashcards
(16 cards)
What does localisation of function refer to?
Specific functions have specific locations in the brain
What is the motor cortex responsible for?
The generation of voluntary motor movements - located in frontal lobe along the precentral gyrus
Both hemispheres have a motor cortex, with the motor cortex on one side of the brain controlling the muscles on the opposite side of the body
Regions are arranged logically next to each other e.g. foot is next to leg region
What is the somatosensory cortex responsible for?
Detects sensory events arising form different regions of the body - located in the parietal lobe along a region called the post central gyrus which processes sensory information related to touch
Produces sensations of touch, pressure, pain and temperature which then localises to specific body regions
Both hemispheres have a somatosensory cortex with the cortex on the one side of the brain receiving sensory info from the opposite side of the body
What are the visual centres responsible for responsible for?
Primary visual centre is the visual cortex - located in the occipital lobe
However, visual processing actually begins in the retina (light enters and strikes the photoreceptors- nerve impulse then transmitted to the brain via the optic nerve - majority terminate in the thalamus which acts as a relay station - passing info to visual cortex
Visual cortex spans both hemispheres with the right hemisphere receiving its input from the left hand side and vice versa
What are auditory centres for?
Concerned with hearing - the auditory cortex - located mainly in temporal lobes
Auditory pathways begin in the cochlea in the inner ear where sound waves are converted into impulses - travel via auditory nerve auditory cortex where basic decoding takes place - then go to the thalamus acts as a relay station which carries out further processing
last stop is the auditory cortex which may result in an appropriate response
What are the two language centres?
Brocas area
Wernickes area
What is Brocas area to do with?
Related to speech production
What is Wernickes area to do with?
Important in the comprehension of language
What was the name of Broca’s patient? and what was his unusual disorder?
Tan
He could understand spoken language but was unable to speak nor express his thoughts through writing (he found Borca’s area as critical for speech production)
Where is Broca’s area located?
Frontal lobe of the brain, usually in the left hemisphere
Where is Wernickes area located?
Temporal lobe
What did Wernicke propose about language?
It involves separate motor and sensory regions located in different cortical regions
Motor region = located in Brocas area - close to area that controls mouth, vocal cords etc
Sensory region = located in Wernickes area - close to regions of brain responsible for auditory and visual input
What is the name of the neural loop running between Broca and Wernickes area?
The arcuate fasciculus (one end responsible for production of speech - Broca - other for comprehension - Wernicke)
Why is the idea of communication potentially more important than localisation?
Wernicke claimed that although different regions of the brain had different specialist functions they are interdependent - must interact
Example: in 1892 neurologist Dejerine described a case in which the loss of an ability to read resulted from damage to the connection between the visual cortex + Wernickes area
Suggest that complex behaviours such as language, reading and movement are built upon gradually as a stimulus enters the brain then move through the structures before a response is produced
Clear that damage to connections between two parts in the brain can resemble damage to the localised region of the brain associated with a specific function
How do studies of aphasia support the idea of language centres?
Brocas aphasia (expressive aphasia) is an impaired ability to produce language - most cases this is caused by damage to the brain
Wernickes aphasia (receptive aphasia) is an impaired ability to understand language/extract meaning - usually caused by brain damage
Why can it be argued language production is more complex than once thought?
Dronkers et al: re-examined the preserved brains of two of Brocas patients using MRI imaging and found that other areas besides Broca’s area could have also contributed to the patients reduced speech abilities - study suggests language and cognition are far more complicated than once thought and involve networks of brain regions rather than being localised to specific areas
