Biopsych 2 Flashcards
What is localisation of function?
The principle that specific functions have specific locations within the brain
What is Franz galls theory of phrenology?
What did Pierre flourens do?
The study of the structure of the skull to determine a persons character and capacity
Used animal experiments to demonstrate main divisions of the brain were responsible for different functions.
Since the 19th cent, techniques have grown considerably
What is the motor cortex:
Role
Location
Responsible for generation of voluntary movements
Located in frontal lobe along pre central gyrus
Motor cortex on each side of brain- left responsible for muscles on right vice versa
Diff parts of motor cortex control diff body parts and they are logically offered (eg part that control foot is next to part that controls leg)
What is the somatosensory cortex?
Located?
Detects sensory events in diff parts of the body
Located in parietal lobe along the post central gyrus
Uses sensory info from skin to produce sensations of touch pressure pain temp and localises it to specific regions of body
Like motor cortex, one on each side and cross wired
What is the post central gyrus?
Area of cortex dedicated to processing of sensory info related to touch
where is the primary visual center of the brain?
where does visual processing actually begin? then where does it go?
in the visual cortex in the occipital lobe. visual cortex spans both hemispheres (left receives info from right vf vice versa)
begins in retina where light strikes photoreceptors. nerve impulses are then transmitted to brain by optic nerve
some nerve impulses then travel to parts of brain to be involved in coordination of circadian rhythms but most terminate in thalamus which passes info onto visual cortex
what is the auditory center? where is it? describe the auditory pathway
concerned with hearing
mostly lies within temporal lobes on both sides in the auditory cortex.
pathway starts in cochlea where sound waves are converted to nerve impulses which travel to auditory cortex by auditory nerve
first stop is brain stem where basic decoding happens, then thalamus where further processing occurs. ends at auditory cortex which recognises sound and generates response
what are the 2 language centers?
broca’s area and wernicke’s area
what is broca’s area?
posterior portion of left frontal lobe
critical for speech production
discovered by paul broca due to patient who could only say ‘tan’ but could understand speech. also studied others with similar problems and lesions in left frontal hemisphere
what is wernicke’s area?
posterior portion of the left temporal lobe???
critical in speech understanding
his patients could speak but not understand
what did wernicke propose?
language involves separate motor and sensory regions.
motor region in brocas is close to area that control mouth, tongue, vocal cords.
sensory region in wernicke’s is close to part of brain responsible for auditory/visual input
there is a neural loop between brocas and wernickes
evaluation of localisation of function and language centres
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not everyone agrees functions are localised eg equipotentiality theory (lashley 1930) suggests basic motor and sensory functions are localised but more complex arent. says intact areas of cortex can takeover responsibilities following injury. says effect of damage is determined by extent not location
research suggests how areas communicate is more important that which region controls specific process. wernicke claimed areas are interdependent. eg french neurologist described case where loss of ability to read led to damage to connection between visual cortex and wernickes area. suggests complex behaviours move through diff structures before response produced. damage to connection between any 2 points in this process leads to impairments similar to damage to localised brain region for that specific function
individual diff- eg bavelier et al 1997 did silent reading study and found variability in patterns of activity between people. found activity in right temp lobe, left front, temp, occip lobes. gender differences- harasty et al 1997 found larger brocas and wernickes in women due to greater use of language
language may not be confined to brocas- bronkers et al 2007 examined lesions using MRI and found other areas may have contributed to reduced speech. significant as lesions in brocas usually cause temporary disruption- suggests speech is complex and network not localised
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support for language centres from aphasia studies eg brocas and wernickes. expressive aphasia- cant produce language shows brocas is important for speech. receptive aphasia- cant understand language shows wernickes is important in comprehensive
case study evidence- Gage, Tan, HM
what is hemispheric lateralisation?
the fact that 2 halves of the brain arent entirely alike and each hemisphere has functional specialisms
how are the 2 hemispheres attached? what does this mean?
the corpus collosum ( a bundle of nerve fibers that connect the 2 halves)
means info can be sent from one half to other and we can for example, talk about things experienced in right hemisphere despite left for language
what is a commisurotamy?
cutting through the corpus collosum as treatment for severe epilepsy.
prevents violent electrical activity from crossing from one hemisphere to another. known as split-brain patients
describe Sperry and Gazinga’s research 1967
studied capabilities of split-brain patients. sent info to one hemisphere to study hemispheric lateralisation as corpus collosum is cut so info cant travel to other spot
-ppt stares at dot (so info only goes to 1 visual field)
- picture shown to 1 visual field for 1/10 second (so cant move eyes)
-found that picture shown in rvf could be described but not drawn (info goes to left hemisphere-left for language)
- picture shown to lvf could draw with left hand (controlled by right hemisphere). can only describe when theyve drawn it
- same concept with holding something in left/ right hand
what have we learnt from split brain reserach?
differences between hemispheres (left for language and right for visual-spatial processing and facial recognition)
but hasnt shown that brain is organsied into discrete regions w specific tasks and instead suggests connectivity between diff regions is as important as operation of diff parts
evaluate lateralisation
assumed that it leads to increased neural processing capacity- using only one hemisphere to engage in task means other is free to engage in another function but little evidence for this. rogers et al 2004 found that (in chickens), lateralisation is associated w ability to perform 2 tasks simultaneously- does provide some evidence that lateralisation increases efficiency
lateralisation changes w age- lateralised patterns in younger people seem to become bilateral when older. szaflarski et al 2006 found language is more lateralised to left when getting older but at 25, lateralisation decreases each decade. may be cuz using other hemisphere may compensate for age related decline in functions
evaluate split brain reserach
gazzinga 1998 suggests some early discoveries have been disconfirmed. eg originally suggested right cant handle any language but case studies have opposed this (JW learnt to speak out of right)
limitations of the actual research- many studies only have around 3 ppts. conclusions drawn from individuals w confounding physical disorder.
evaluate Sperry and Gazzinga’s study
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scientific - consistent results, same task, shown for 1/10s
applications- develop treatments, understand roles of hemispheres
high internal validity- presentation of stimulus to one hemisphere means most likely measuring what each hemisphere does
good ethics- corpus collosum already cut-no manipulation of IV, all consented, could withdraw, fully informed
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small, atypical sample so not generalisable
gazzinga- discoveries disproved
lack of controls- no valid control group, some on medication, some had more disconnection than others
low ecological validity- irl people have unrestricted view so info not selectively delivered to one hemisphere
what is brain plasticity?
the brain’s ability to change and adapt as a result of experience.
what is functional recovery?
moving functions from damaged area of the brain after trauma to another area
what types of experience can change neural organisation?
plasticity as a result of life experience- gain new experiences means nerve pathways that are frequently used develop stronger connections and ones barely used die. this pruning allows brain to adapt. natural decline with age so ways of reversing this have been found eg Boyke et al 2008 found evidence of brain plasticity in 60 year olds (increased grey matter in visual cortex when learnt to juggle)
playing video games- complex cognitive and motor demands. Kuhn et al 2014 compared control w group that was trained for 2 months 30 mins a day at video game and found increased grey matter in various brain areas that wasnt found in control
meditation- davidson et al 2004 compared 8 monks with 10 volunteers with no meditation experience. both fitted with electrical sensors and asked to meditate. more gamma wave (coordinate neuron activity) activity in monks. students showed slight increase in gamma. so makes short term changes as well as long term (monks had more before experiment
what are the mechanisms for functional recovery?
regenerative developments in brain due to its plasticity
neural masking and stem cells
what is neural unmasking?
wall 1977 discovered dormant synapses (blocked)
normally would be ineffective because rate of neural input is too low for them to be activated
increased rate of input that occurs when surrounding area is damaged can unmask them
this gives way to the development of new structures over time.
how can stem cells lead to recovery of a stroke?
unspecialised cells that can take on characteristics of nerve cells
diff views of how this works:
cells implanted into the brain can directly replace dead cells
or
transplanted stem cells can secrete growth factors that rescue injured cells
or
transplanted cells form a neural network which links uninjured brain site where stem cells are made with the damaged region of the brain
