biopsychology 2 Flashcards
what does the brain stem do?
controls basic life functions (eg breathing, heart)
what does the cerebellum do?
basic motor control, balance and some simple learning
what does the cerebrum do?
higher functions (emotion, complex perception, thinking)
what does localisation of function mean?
certain areas of the brain hold particular functions
what is localisation?
the theory that specific areas of the brain are associated with particular functions
what does a laterised brain function mean?
they are concentrated on one side of the brain
what does a cross-laterised brain function mean?
the right side of the brain controls the left side of the body (in general, brain function is cross-lateralised)
what does localisation further assume?
if a certain area of the brain becomes damaged through illness or injury, the function associated with that area will also be affected
what is the opposing theory to localisation?
holistic theory → suggests that all parts of the brain are involved in the processing of thought and action
what is the cerebrum?
the largest part of the brain. it is divided into two hemispheres (left and right)
what is the outermost layer of the cerebrum?
the cerebral cortex
how does the cerebral cortex link to our sensory systems?
each of our sensory systems sends messages to and from this cerebral cortex
what are the hemispheres separated by?
the corpus callosum (a bundle of fibres)
what does the corpus callosum allow?
allows messages that enter the right
hemisphere to be conveyed to the left hemisphere and vice versa
each hemisphere is divided into…
four lobes:
➢ the frontal lobe
➢ the parietal lobe
➢ the temporal lobe
➢ the occipital lobe
what does the frontal lobe do?
the location for awareness of what we are doing within our environment (our consciousness)
what does the parietal lobe do?
location for sensory movements
what does the occipital lobe do?
location for vision
what does the temporal lobe do?
location for the auditory ability and memory acquisition
what are the areas of the brain that i must use?
-motor cortex
-somatosensory
-visual cortex
-auditory cortex
language centres:
broca’s and wernicke’s areas
MOTOR CORTEX
(function, effects of damage, location)
function:
responsible for voluntary movements by sending signals to muscles in the body
effects of damage
may result in loss of control over fine movements
location
-in the frontal lobe (goes across both sides)
-the motor area in the left hemisphere controls movement on right & vice verses
SOMATOSENSORY AREA
(function, effects of damage, location)
function
receives sensory information from the skin to produce sensations related to pressure, pain, temperature etc (& sense of body movement)
effects of damage
causes decreased sensory thresholds
location
in the parietal lobe
VISUAL CORTEX
(function, effects of damage, location)
function
receives and processes visual information.
it contains different parts which process different types of visual information.
effects of damage
damage to the left hemisphere can produce blindness in part of the right visual field in both eyes
location
in the occipital lobe
AUDITORY CORTEX
(function, effects of damage, location)
function
-analyses and processes acoustic information
-information from the right ear goes primarily to the left hemisphere and information from the left ear goes primarily to the right hemisphere
effects of damage
may produce partial hearing loss
location
in the temporal lobe
where are language areas found?
predominantly on the left side of the brain
BROCA’S AREA
(function, effects of damage, location)
function
responsible for speech production
effects of damage
broca’s aphasia – slow, laboured and disjointed speech
location
in the left frontal lobe
**WERNICKE’S AREA*
(function, effects of damage, location)
function
responsible for speech comprehension
effects of damage
causes wernicke’s aphasia
➢ the person struggles to understand language and often produces sentences that are fluent but meaningless
➢ nonsense words (neologisms) may also be produced
location
left temporal lobe
which case study supports the theory of brain localisation?
phineas gage
aim of phineas gage case study:
to explain the cause of Gage’s change of personality
method of phineas gage case study:
-an explosion caused a meter length iron pole (tamping iron) to be hurled first through his left cheek
-it passed behind his left eye, and exited his brain and skull from the top of his head
results of phineas gage case study:
-he survived, and after months of recovery wanted to regain his job
-before the accident he was seen as God-fearing, kind and reserved
-his personality had changed to someone who was now boisterous, rude and grossly blasphemous
-his friends said he was “no longer gage.”
conclusion of phineas gage study:
-gage has taught us a great deal about the complexity of psychological processes that occur in the human brain
-he provides evidence of some localisation of function in the brain
strengths of the theory of localisation:
-evidence from the case study of phineas gage
-evidence from brain scans (peterson 1988)
strength / ao3 - evidence from the case study of phineas gage
P - there is evidence to support the theory from the case study of phineas gage
E - he suffered an accident where a piece of metal damaged most of his left frontal lobe
↳ although he survived, he experienced changes in personality, such as loss of inhibition and increased anger
↳ this suggests that that certain aspects of personality are localised within the frontal lobe
L - this therefore supports the theory that functions in the brain are localised
strength / ao3 - evidence from brain scans (peterson 1988)
S - there is evidence to support localisation of function from brain scans
E - oeterson (1988) 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
L - this supports the idea that that language functions are localised in different areas of the brain and so supports the theory of localisation of function
criticisms of the theory of localisation:
-theory of holistic brain function contradicts the theory of localisation
-the placisity of the brain contradicts the theory of localisation
ao3 / criticism - theory of holistic brain function contradicts the theory of localisation
P - not all researchers agree with the view that cognitive functions are localised in the brain
E - there is evidence to show that higher cognitive functions are not localised, but instead are distributed in a more holistic way within the brain
↳ lashley (1950) removed 10-50% of the cortex in rats that were learning a maze, no particular area seemed to be more important in terms of the rat’s ability to learn the maze
↳ the process of learning seemed to require every part of the cortex
E - from this research, lashley proposed the theory of equipotentiality → suggests that the basic sensory and motor functions are localised, but the higher functions are not
L - this evidence contradicts the theory of localisation
ao3 / criticism - the placisity of the brain contradicts the theory of localisation
P - a further argument against localisation is that of plasticity
E - after brain damage, the brain appears to be able to reorganise itself to recover loss in function (although this does not always happen)
↳ intact areas of the cortex could take over responsibility for specific functions following injury to the area normally responsible for that function
L - this theory of plasticity supports the holistic theory (all parts of the brain are involved in processing of thought and action) rather than localisation
Albert suffered a stroke to the left hemisphere of his brain. The stroke damaged Wernicke’s area and the motor cortex. Use your knowledge of the functions of Wernicke’s area and the motor cortex to describe the problems that Albert is likely to experience.
(4 marks)
wernicke’s area is responsible for speech comprehension (in the left hemisphere)
↳ albert will be unable to produce coherent speech. his speech will be fluent but will not make any sense
(wernicke’s aphasia)
the motor centre is responsible for voluntary movement
↳ as Albert’s left hemisphere is damaged and the motor centre’s functions are cross lateralised, he will have difficulty with movement on his right side
what is a seizure?
an electrical disturbance in the brain
what is hemispheric lateralisation?
the idea that the two halves (hemispheres) of the brain have different functions
how did surgeons learn to reduce seizures in epilepsy patients?
-surgeons found that separating the hemispheres meant seizures could be controlled in very severe cases of epilepsy
-this is because they were mainly contained in one hemisphere
what medical procedure is used to split the hemispheres of the brain and how is it done?
hemispheric deconnection/commissurotomy/split-brain surgery
the corpus callosum was severed
who conducted the split brain research and when?
sperry & gazzaniga (1968)
split brain research sample:
He was a doctor working in a hospital in California, USA.
-11 patients who had undergone hemispheric deconnection for epilepsy
-sperry did not sever the corpus callosum of the epileptic patients himself, he was an opportunist
-he mpared their functioning to people without epilepsy who had not undergone the procedure
what did the spilt brain surgery mean about communication?
messages could not be sent from one hemisphere to another
method of split brain research:
sperry used a tachistoscope to split the visual field & present information to either the left visual field (processed by the right hemisphere) or the right visual field (processed by the left hemisphere)
the information was presented for about 1/10th of a second
sperry and gazzaniga conducted many different experiments, including describe what you see tasks, tactile tests, and drawing tasks.
1) in the describe what you see task, a picture was presented to either the left or right visual field and the participant had to simply describe what they saw
2) in the tactile test, an object was placed in the patient’s left or right hand and they had to either describe what they felt, or select a similar object from a series of alternate objects
3) finally, in the drawing task, participants were presented with a picture in either their left or right visual field, and they had to simply draw what they saw
FINDINGS:
describe what you see: picture presented to the right visual field
(processed by left hemisphere)
the patient could describe what they saw, as language production is mainly localised in the left hemisphere
FINDINGS:
describe what you see: picture presented to the left visual field
the patient could not describe what was shown and often reported that there was nothing present
↳ because the image was processed in the right visual field and there are no language centres here
FINDINGS:
tactile tests: objects placed in the right hand
(processed by the left hemisphere)
-the patient could describe verbally what they felt, or they could identify the test object presented in the right hand (left hemisphere), by selecting a similar appropriate object, from a series of alternate objects
FINDINGS:
tactile tests: objects placed in the left hand
(processed by the right hemisphere)
-the patient could not describe what they felt and could only make wild guesses
-however, the left hand could identify a test object presented in the left hand (right hemisphere), by selecting a similar appropriate object, from a series of alternate objects
FINDINGS:
drawing tasks: picture presented to the right visual field
(processed by left hemisphere)
-while the right-hand would attempt to draw a picture, the picture was never as clear as the left hand
FINDINGS:
drawing tasks: pictured presented to the left visual field
(processed by right hemisphere)
-the left-hand (controlled by the right hemisphere) would consistently draw clearer and better pictures than the right-hand (even though all the participants were right-handed)
-this demonstrates the superiority of the right hemisphere when it comes to visual motor tasks.
FINDINGS:
composite words: (key / ring)
-they would say ring as that is processed by the left hemisphere (has language areas)
-they would be able to pick up the key with their left hand as that was processed by the right hemisphere
conclusion of the split brain research study:
-the findings of sperry and gazzaniga’s research highlights a number of key differences between the two hemispheres
↳ the left hemisphere is dominant in terms of speech and language
↳ the right hemisphere is dominant in terms of visual-motor tasks
what type of experiment did sperry use?
a quasi (natural) experiment
strengths and weaknesses of quasi experiments:
strengths:
controlled conditions – standardised procedures (good internal validity)
weaknesses:
lack of ecological validity – in real life the patients can adjust visual position so info goes to both hemispheres (therefore
data was artificially produced)
strength of sperry’s study:
-high internal validity