localisation of function in the brain + hemispheric lateralisation Flashcards
what is meant by localisation ?
- specific areas of the brain are associated with particular physical and psychological functions
What does
Phineas Gage’s case provide evidence for ?
- this case provides early evidence to support localisation of function
- since Gage’s brain damage was located in the frontal lobe , his case study offered evidence that the frontal lobe is related to personality
why do we have to be cautious when using Gage’s case study ?
- because the results cannot be generalised to the whole population because this is such a unique injury
what is meant by lateralisation ?
- the dominance of one hemisphere of the brain for particular physical and psychological functions
what is meant by the hemispheres ?
- the brain is divided into 2 hemispheres: the left and the right
- each hemisphere is considered to be responsible for specific functions
what is the main difference between the hemispheres concerned with ?
language
- as language areas are mostly found in the left hemisphere
Broca’s area
location
function
damage effect
- located in the left frontal lobe
- speech production + covert thought into speech
- aphasia (speech lacks fluency and is slow)
Wernickle’s area
location
function
damage effect
- located in the left temporal lobe
- speech comprehension + recognition of spoken word
- difficult to understand others + producing meaningful speech
frontal lobe function ?
- movement
- mood
- problem solving
- concentrating / thinking
- behaviour
- personality
temporal lobe function ?
- hearing
- language
- memory
Brain stem function ?
- consciousness
- breathing
- heart rate
cerebellum function ?
- posture
- balance
- co ordination of movement
occiptal lobe function >
- vision
- perception
parietal lobe function ?
- sensation
- language
- attention
- perception
- body awareness
blurt phineas Gage study
lashley’s research AIM
to show how the processes involved in learning are not localised but distributed in a more holistic way in the brain
Lashley’s method
Lashley removed areas of the cortex in rats that were learning a maze
no area was proven to be more important than any other area in terms of the rats ability to learn the maze
what percentage of the rats brain did Lashley remove?
between 10 % and 50%
Lashley research results
the process of learning appeared to require every part of the cortex, rather than being confined to a particular area
Lashley research conclusion
- this seems to suggest that learning is too complex to be localised and requires the involvement of the whole brain
Hubel and Wiesel research AIM
to demonstrate the effect of visual impairment on the visual system
Hubel and Wiesel
- method
- one eyelid was sutured shut on newborn kittens
- the kitten was allowed to grow up that way, and when it reached adulthood (around 6 months ), its eyelid was opened again
- recording were made of the electrophysiological activity in each kittens eyes
Hubel and Wiesel
results
- recordings showed an abnormally low number of neurons reacting in the eye that had been sutured shut
- and an abnormally high number in the other eye
- macroscopic observation of the visual cortex showed that the ocular dominance columns for the eye that had been left open had grown larger, while those for the eye that had been closed had shrunk
Hubel and Wiesel
conclusion
- showed that if a kitten is deprived of normal visual experience during a critical period at the start of its life, the circuitry of the neurons in its visual cortex is irreversibly altered
Hubel and Wiesel AO3
- later experiments showed that suturing a cats eye shut had no effect on its visual cortex unless the visual deprivation took place in the first 3 months of the cats life
