A2 Biopsychology Flashcards
What are the strengths of localisation of function?
. Phineas gage ‘no longer gage’ after injury to frontal lobe
.brain scans- Peterson (1988) found only Broca’s area used in reading task and only wernickes area used in listening task
. Neurosurgical evidence- Dougherty (2002) put lesions in cingulate gyrus of OCD sufferers- 30% made full recovery, 14% made partial recovery
What are the limitations of localisation of function
Lashley’s rats- removed 10-50% of rats brains and no area affected them doing the maze more than others- shows their brains work holistically.
Plasticity- if brain undergoes trauma in some cases brain is able to reorganise itself to regain function- shows holism
Dick and Trembly- found only 2% of modern researches believe language is completely controlled by B and W areas- fMRI scans have showed language is holistic
What is hemispheric lateralisation
The idea that the two halves of the brain are functionally different and that each hemisphere has specific functions
Is language lateralised?
Yes- B and W areas are both in the left hemisphere
What side of the brain contributes to emotional context?
Right
RH is the synthesiser
LH is the analyser
Is movement lateralised?
No- but it is cross wired (contralateral wiring) RH controls movement on left and vice Versa
Is vision lateralised
No- it is both contralateral and ipsilateral each eye gets info from RVF and LVF and each is processed in the opposite side of the brain (LH or RH)
Outline Sperry’s experiment
Tested on 11 males with commissurotomy’s
Patients would stare at cross in the middle of a screen and either and image or a word would flash in the LVF and RVF
What were the findings of Sperry’s experiment
Describe what you see- when object or word was displayed in right RVF the patient could easily describe it as was processed in LH
Recognition by touch- although patients could not verbally say what they saw in LVF and processed in RH they could pick up the object they saw when presented with and array of different things- they could also select the most similar (cigarette- ashtray etc)
What were the findings of Sperry’s experiment
If word or object shown in RVF patient could easily say what it was as processed by LH. If object or word shown in LVF patient could not remember was they saw
Even though patients could not verbally describe stimulus in LVF they could pick up the object from behind a screen- they could also select object most similar to the one they saw (cigarette- ashtray etc)
What were the findings of Sperry’s research
If word or object shown in RVF patient could easily say what it was as processed by LH. If object or word shown in LVF patient could not remember was they saw
Even though patients could not verbally describe stimulus in LVF they could pick up the object from behind a screen- they could also select object most similar to the one they saw (cigarette- ashtray etc
What does Sperry’s research tell us about hemispheric lateralisation
RH is non verbal
LH is verbal
RH can still process information non verbally
When racy image showed in LVF patient would giggle even though they didn’t know what they saw
What are the strengths of hemispheric lateralisation
Highly scientific supporting evidence- Fink et Al (1996) identified with PET scans that during a visual task when an image was looked at holistically RH was more active but when asked to focus on details LH was more active
Real world applications- Gazzaniga found that spilt brain patients are better at identifying an odd one out in a group because LH has better cognitive abilities which are not interfered with by RH. Rogers showed chickens with spilt brains could feed and look for predators simultaneously.
High internal validity of evidence- Sperry’s experiment was highly controlled- cross used to focus on etc
What is a limitation of hemispheric lateralisation?
Sperry’s research lacks generalisability- only carried out on 11 men all who previously had severe epilepsy
What is the definition of plasticity
Your brains ability to change and adapt as a result of new experiences and learning. As a child you have thousands of synapses per neuron but these are cut by ‘synaptic pruning’ suggesting your brain can change during adulthood.
What is the definition of functional recovery
When brain adapts to trauma by getting other parts of brain to carry out function of damaged part
Outline maguires study
Compared brains of black cab drivers to control group chosen by matched pairs design
Significantly more grey matter in posterior hippocampus of black cab drivers
Posterior hippocampus is for spatial awareness
What are the strengths of plasticity
Maguires experiment highly controlled- used matched pairs design and MRI scans to gather data
Draganski observed 3 medical students before and after exam and all 3 had either larger or more connections in posterior hippocampus and parietal cortex
Michelli found that people who were bilingual had bigger parietal cortex’s than people who weren’t
What are the strengths of plasticity
Maguires experiment highly controlled- used matched pairs design and MRI scans to gather data
Draganski observed 3 medical students before and after exam and all 3 had either larger or more connections in posterior hippocampus and parietal cortex
Michelli found that people who were bilingual had bigger parietal cortex’s than people who weren’t
What is a limitation of plasticity
Maguires results may not be reliable- none of the taxi drivers were tested before they took their ‘knowledge test’
How does Jody support idea of plasticity and functional recovery
Had RH removed at 3
LH took up all the function of RH
Can function almost perfectly with only slight paralysis on left side
What happens to the brain during recovery
New synaptic connections
Secondary neural pathways created
Axonal sprouting
Denervation super sensitivity
Recruitment of the homologous area
What are the strengths of functional brain recovery
Real work application- help people recover from strokes etc. strapping hand behind back ( constraint induced movement therapy)
Supporting evidence- Bezzola gave people aged 40-60 40 hours of golfing lessons and their brain structures changed
Schneider found that people who stayed in education for 16 years had 40% chance of recovering from traumatic brain injuries- if in education for under 12 years 10% chance of recovery
What is a limitation of functional recovery
Not always a good thing- phantom limb syndrome occurs when somatoes sensory area remains idle for too long and another part of the brain takes up its function
What is a limitation of functional recovery
Not always a good thing- phantom limb syndrome occurs when somatoes sensory area remains idle for too long and another part of the brain takes up its function
How does an fMRI scan work
Measures changes of blood flow in brain using radio waves and a magnetic field. As a result of these changes in blood flow, researchers can produce a map showing which areas of the brain are being used
What are the strengths of fMRI
No radioactive tracer (risk free)
Clear, high resolution images
Shows where functions are localised
What are the weaknesses of fMRI
Very expensive
Patient must remain still for long period of time (bad for children, ADHD and the elderly)
Poor temporal resolution (5 second delay between event and imaging)
How does an EEG work
Measures electrical activity in the brain. Electrodes on the scalp pick up small electrical activity from functioning brain cells. When the signals from different electrodes are graphed over a period of time you get an EEG
What are the strengths of EEG
Can be used to diagnose epilepsy, sleep disorders, Alzheimer’s
High temporal resolution (detects electrical activity in under 1 second)
What are the weaknesses of EEG
General measure- only picks up on groups of neurons firing electrical impulses not individual
Researchers can find it hard to decipher when different but adjacent areas are firing
How does an ERP work
Using an statistical averaging technique researchers can tease out all extraneous brain activity from original EEG leaving only the brain activity related to the presentation of a specific stimulus.
What remains are event related potentials: types of brainwaves that are triggered by particular events. Research has revealed many different forms of ERP that can be linked to cognition or perception
What are strengths of ERP
More specific than EEG readings
Very good temporal resolution as derived from EEG
What are the weaknesses of ERP
To be successful all interference must be eliminated
Not standardised- lots of different ways it is done depending on the researches
How does a post mortem work?
Used to establish the underlying neurobiology of a particular behaviour. For example, researches study a person who displays interesting behaviour that could stem from brain damage. Then when the person dies they can examine their brain to see if they were right. An example of this is Broca and Tan
What are biological rhythms
Distinct patterns of changes in body activity that conform to cyclical time periods. For example the sleep-wake cycle. These cycles are influenced by endogenous pacemakers and exogenius zeitgebers.
What is a cycle that occurs ONCE every 24 hours called
Circadian rhythm