localisation of function in the brain Flashcards
localisation of function definition
the theory that different areas of the brain are responsible for specific behaviours, processes or activities
motor area definition
a region of the frontal lobe involved on regulating movement
somatosensory area definition
an area of the parietal lobe that processes sensory information such as touch
visual area definition
a part of the occipital lobe that receives and processes visual information
auditory area definition
located on the temporal lobe and concerned with the analysis of speech-based information
Broca’s area definition
an area of the frontal lobe in the left hemisphere (in most people), responsible for speech production
Wernicke’s area definition
an area of the temporal lobe (encircling the auditory cortex) in the left hemisphere (in most people), responsible for language comprehension
who discovered in the 19th century that specific areas of the brain are associated with particular physical and psychological functions
Broca and Wernicke
what was thought before Broca and Wernicke’s research (and case of Phineas Gage)
supported the holistic theory of the brain- that all parts were involved in the processing of thought and action
what did Broca and Wernicke argue
localisation of function
what can localisation of function sometimes be called
cortical specialisation
what is localisation of function
idea that different parts of the brain perform different tasks and are involved with different parts of the body. it follows that then if a certain area of the brain becomes damaged the function associated with that area will become affected
what is the cerebrum (main area of the brain) divided into
2 symmetrical halves called the left and right hemisphere
what is controlled by a certain hemisphere
some of our physical and psychological functions are controlled or dominated by a particular hemisphere which is called lateralisation
what is lateralisation
some of our physical and psychological functions are controlled or dominated by a particular hemisphere
what is activity on the left side of the body controlled by
right hemisphere
what is activity on the right side of the body controlled by
left hemisphere
what hemisphere is language linked to
left
what is the cerebral cortex
the outer layer of both hemisphere
what is the cortex of both hemispheres subdivided into
4 centres called the lobes of the brain
what are the 4 lobes of the brain
-frontal lobe
-parietal lobe
-occipital lobe
-temporal lobe
what is a lobe
a part of an organism that is separate in some way from the rest. each lobe in the brain has different functions
where is the motor area
back of the frontal lobe- in both hemispheres
motor area function
controls voluntary movement in the opposite side of the body
what does damage in the motor area lead to
may result in a loss of control over fine movements
where is the somatosensory area
front of both parietal lobes which is separated from the motor area by a valley called the central sulcus
somatosensory area function
where sensory information from the skin is represented. the amount of somatosensory area devoted to a particular body part denotes its sensitivity (receptors in our face and hands occupy over half of the somatosensory area
where is the visual area
in the occipital lobe at the back of the brain
how do eyes send information
each eyes sends information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex
what can damage in the left hemisphere cause (sight)
produce blindness in part of the right visual field of both eyes
where is the auditory area
temporal lobes
auditory area function
analyses speech-bases information.
damage to auditory area
may produce partial hearing loss. the more extensive the damage, the more extensive the loss. in addition damage to a specific area of the temporal lobe of Wernicke’s area may affect the ability to comprehend language
where is language restricted to in most people
left side of the brain
what did Broca identify
a small area in the left frontal lobe responsible for speech production
who is Broca
a surgeon
Broca’s area function
speech production
what does damage to broca’s area cause
Broca’s aphasia which is characterised by speech that is slow and laborious and lacking in frequency. also have difficulties with prepositions and conjunctions
Broca’s famous patient
‘Tan’ as that was the only word he could say
what was Wernicke describing (linked to Wernicke’s aphasia)
people who has no problem producing language but severe difficulties understanding it so the speech they produced was fluent but meaningless
where is Wernicke’s area
left temporal lobe
Wernicke’s area function
responsible for language understanding
damage to Wernicke’s area
Wernicke’s aphasia which causes production of nonsense words (neologisms) as part of the context to their speech
what as Phineas Gage doing to cause the accident
whilst working on the railroad preparing to blast a section of rock with explosions to create a new railroad, he dropped his tramping iron onto the rock, causing the explosive to ignite
what happened to Phineas Gage during accident
meter length pole went through his left cheek, passing behind his left eye and exiting his skull from the top of his head taking a proportion of the brain which was mainly his left frontal lobe
what happened to Gage after accident
personality changed as accounts suggest her had turned from someone who was calm and reserved to someone who was quick-tempered and rude
why is Gage seen as a landmark case in science
change to his temperament following the accident suggests that the frontal lobe may be responsible for regulating mood
strength of localisation of functions - evidence from neurosurgery
-damage to areas of the brain has been linked to mental disorders
-neurosurgery (surgery on the brain) is a last resort methos for treating some mental disorders, so targeting specific areas of the brain which may be involved. for example a cingulotomy isolates a region called to cingulate gyrus which has been implicated with OCD. Dougherty et al (2002) reported on 44 people with OCD who had undergone. at post-surgical follow-up after 32 weeks 30% had met criteria for successful response to surgery and 14% partial response –> success suggests that behaviours associated with serious metal disorders may be localised
strength of localisation of functions - evidence from brain scans
-brain scans supports the idea that many everyday brain functions are localised
-petersen et al (1988) used brain scans to demonstrate Broca’s area was active during a reading task. a review of long-term memory studies by Buckner and Peterson (1996) revealed that semantic and episodic memories reside in different parts of the prefrontal cortex. these studies confirm localised area for everyday behaviours –> objective methods for measuring brain activity provided sound scientific evidence that many functions are localised
limitation of localisation of functions - counterpoint to evidence from brain scans
-challenge to localisation of function theory comes from Lashley (1950). Lashley removed area of the cortex (between 10 and 50%) in rats that were learning the route through a maze. no cortex area was found to be more important than any other in terms of the rat’s ability to learn the route. the process of learning seemed to require every par of the cortex not just a particular area –> higher cognitive processes such as learning are localised but distributed in a more holistic way in the brain
limitation of localisation of function - language localisation questioned
-language may not just be localised to Broca’s and Wernicke’s areas
-a recent review by Dick and Tremblay (2016) found that only 2%of modern researchers think that language in the brain is completely controlled by Broca’s and Wernicke’s areas. advanced in the brain imaging techniques, such as fMRI, mean that neural processes in the brain can be studies with more clarity than ever before. it seems that language function is distributed far more holistically in the brain than was first thought. so called language streams have been identifies across the cortex, including brain regions in the right hemisphere, as well as subcortical regions such as the thalamus –> suggests that, rather than being confined to a couple of key areas, language maybe organised more holistically in the brain, which contradicts localisation theory
evaluation of localisation of function in the brain - case study evidence
-unique cases of neurological damage support localisation theory, such as the case of Phineas Gage
-however, there are problems with case studies. it is difficult to make meaningful generalisations from the findings of a subjective interpretation of the researcher
