Section 6 : Biopsychology - Localisation of Function Flashcards
What is the localisation of function
Certain areas of the brain that are thought to be responsible for particular functions e.g. vision, language etc.
What is the localisation of function consisted of
- Motor Cortex
- Broca’s Area
- Somatosensory Cortex
- Visual Cortex
- Auditory Cortex
- Wernicke’s Area
What does the motor cortex do
Controls voluntary movement
What does the Broca’s area do
Responsible for production of speech
What does the auditory cortex do
Processes information from our ears
What does Wernicke’s Area do
Responsible for the understanding of language
What does the Visual Cortex do
Processes information from our eyes
What does somatosensory cortex do
Processes information about touch, pain, temperature and proprioception (position of the body)
How are the two hemispheres if the brain connected
Corpus Callosum
What is meant by different functions are dominant in each hemisphere
- Broca’s and Wernicke’s area are found on the left hemisphere so the left side handles the bulk of language alongside logic, analysis problem solving etc.
- the right hemisphere is more concerned with things like spatial comprehension, emotions and face recognition.
This is known as hemispheric lateralisation of function
What is meant by each hemisphere deals with information from the opposite side of the body
E.g. Information from the right visual field goes to the visual cortex in the left hemisphere. Same goes for the other way around. The information then passes thru the corpus callosum to whichever side needs to deal with it.
What was the Method of Sperry 1968
- involved many case studies and experiments, 11 ppts who underwent split brain surgery due to severe epilepsy
- control group with no hemisphere disconnection
- in one experiment ppts covered one eye and looked at fixed point on a projected screen.
- pictures were projected onto the right or left of the screen at high speeds so that there was no time for eye movement.
What was the results of Sperry 1968
- if the picture was in the right visual field, all ppts could say or write what it was without a problem
- if the pictures was flashed onto the left, the split brain ppts couldn’t say or write what they saw.
- they could however select a corresponding object with their left hand, which represented what’d been shown to their left eye even though they didn’t know why they had selected this object
What was the conclusion of Sperry 1968
- shows that different areas of the brain specialise in different functions
- left hemisphere can convert sight into spoken and written language
- usually info from the right can be processed to the left but as results show this can’t happen in split brain ppts so info going into the right can’t be converted into language
- However the right hemisphere can still produce a non-verbal response
What are the evaluations of Sperry 1968
+ obtained qualitative and quantitative data meant reliability and validity were increased
- only 11 ppts, very small sample size so hard to generalise to other but would be tough to find more ppts
- epilepsy is usually caused by brain damage and the patients had also been on medication which may have affected their brains, hard to conclude that the way epilepsy patients processed info the same non epilepsy or split brain people would
- criticised for eco validity, experimental situation was artificial difficult to generalise results to real life
What are the three concentric layers the human brain can be viewed as
- central core
- limbic system
- cerebrum
What is the central core
- regulates involuntary processes and the endocrine system to maintain homeostasis
- also known as the brain stem (includes structure like hypothalamus)
What is the limbic system of the brain
- controls emotions
- contains structures like the hippocampus (key in memory)
What is the cerebrum in the brain
- regulates higher intellectual processes
- outermost layer known as cerebrum cortex and each sensory system sends messages to and from here
- made up of left and right hemisphere as well as the corpus callosum
What are the four division of each hemisphere
- occipital lobe (location for vision, back of the brain)
- parietal lobe (location for sensory and motor movements, middle of the brain)
- frontal lobe (location for awareness, front of the brain)
- temporal lobe (location for auditory and memory, below parietal lobe)
What evaluations support the localisation of function in the brain
- brain scan evidence
- case of phineas gage
- neurosurgical evidence
How does brain scan evidence positively support localisation of function in the brain
- Petersen et al used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task, suggesting that these areas of the brain have different functions.
- now number of ways and methods to produce solid evidence for localisation of function
How does the case of Phineas gage support localisation of function in the brain
- his personality had changed from kind and reserved to boisterous, rude and blasphemous.
- be careful about generalising these findings (one rare case about an unfortunate individual)
How does neurosurgical evidence support the localisation of function in the brain
- involves the destruction of healthy brain tissue: lobotomy (removal of the brain tissue) leucotomy (cutting the connections to a particular part of the brain)
- The success of these procedures strongly suggests that symptoms and behaviours associated with serious mental disorders are localised
What evaluations don’t support localisation of function in the brain
- higher cognitive functions aren’t localised
- neuroplasticity
How does higher cognitive functions not support localisation of function in the brain
- Karl Lashley suggests that the basic motor and sensory functions were localised, but that higher mental functions were not.
- Rats had 10-50% of their cortex removed. No area was shown to be more important than any other area of the rats’ ability to learn a maze.
- The process of learning appeared to require every part of the cortex, rather than being confined to a particular area.
- This seems to suggest that learning is too complex to be localised and requires the involvement of the whole brain.
How does neuroplasicity not support localisation of function in the brain
- Cortical remapping- the brain is able to reorganise itself in an attempt to recover the lost function.
- Lashley ‘the law of equipotentiality’ – surviving brain circuits ‘chip in’ so the neurological function can be achieved. There are several cases of stroke victims being able to recover abilities that are lost.
