Lesson 6 - Localisation Of Function Flashcards
What is localisation of function
Localisation of function refers to the principle that functions (e.g. vision, hearing, memory, etc.) have specific locations within the brain. Research has shown that some functions are more localised than others. The motor and somatosensory functions are highly localised to particular areas of the cortex. Other functions are more widely distributed. The language system uses several parts of the brain, although some components, such as speech production, may be localised (Broca’s Area).
What does the visual cortex process
At the back of the brain, in the occipital lobe is the visual centre, which receives and processes visual information. Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right hemisphere. The visual centre contains different parts that process different types of information including colour, shape or movement.
Where are the auditory centres
The auditory centre is located in the temporal lobe and is responsible for analysing and processing acoustic information. Information from the left ear goes primarily to the right hemisphere and information from the right ear goes primarily to the left hemisphere. The auditory centre contains different parts, and the primary auditory centre is involved in processing simple features of sound, including volume, tempo and pitch.
Motor cortex
The motor cortex is responsible for the generation of voluntary movements. It is located in the back of the frontal lobe. Both hemispheres of the brain have a motor cortex, with the motor cortex on one side of the brain controlling the muscles on the opposite side of the body. Different parts of the motor cortex show control over different parts of the body. These regions are arranged logically next to each other e.g. the region that controls the foot is next to the region that controls the leg etc.
Somatosensory cortex
The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature, etc. Different parts of the somatosensory centre receive messages from different locations of the body. Robertson (1995) found that this centre of the brain is highly adaptable, with Braille readers having larger centres in the somatosensory centre for their fingertips compared to normal sighted participants.
What is Broca’s area
Named after Paul broca who treated patients who had difficulty in speech production. He found that they had lesions to the left hemisphere of the frontal lobe. Damage to Broca’s area causes expressive aphasia. This affects language production but not understanding. Speech lacks fluency and have difficulty that helps sentences function, like it and the,
Wernicke’s area
The left hemisphere of the temporal lobe. It was found that those with legions in this area could speak, but were unable to understand language, this is called receptive aphasia. He concluded this area responsible for processing spoken language. It’s connected to Broca’s area in a neural loop
Strengths of localisation of function
It has brain scan evidence of localisation: Peterson et al used brain scans to show how wernicke’s area was active during a listening task (understanding) and how Broca’s area was active during a reading task (speech production). This suggests that language is localised in these 2 areas and because it’s shown through brain scans, increases the validity
Case study evidence - phineas gage suffered brain damage from a pole that forced his temporal lobe outside of his brain. He suffered a complete change of personality, suggesting that personality may be localised to the temporal lobe
Support from aphasia studies - aphasia means the inability to produce or understand speech. Studies have found that those who suffer damage to Broca’s or Wernicke’s area suffer expressive and receptive aphasia.
Weakness localisation of function
Doesn’t explain plasticity - placidity argues against localisation. When the brain gets damaged and a particular functions gets lost, the brain tries to rewrite itself to attempt to compensate for the lost function, suggesting that other brain areas can compensate for the loss of function in another area, such as Wernicke’s area. If another area could compensate then we could still understand speech. Plasticity can compensate for damage of brain localisation
Localisation is reductionist - Lashley found that higher cognitive functions like learning are not localised to specific areas of the brain. He removed areas of the cortex in rats brains and found that no area was more important in terms of the rats ability to run the maze. Running the maze is not localised to specific areas of the cortex suggesting that localisation is reductionist and simplifies our behaviour into specific brain areas
