Biopsychology: The Brain (L6-10) Flashcards
(42 cards)
1
Q
What is localisation of function?
A
- refers to the principle that functions
- e.g. vision, hearing, memory, etc, have specific locations within the brain
2
Q
What is contralateral organisation, LoF?
A
- hemispheres of the cerebrum mainly represent the opposite side of the
body - known as contralateral organisation
- e.g. the left hemisphere of the cerebrum controls movement, sensations and visual and auditory processing on the right side of the body and vice versa
3
Q
What are the different areas of the brain, LoF?
A
- motor cortex
- somatosensory cortex
- visual cortex
- auditory cortex
- Broca’s area
- Wernicke’s Area
4
Q
What does the motor cortex do?
A
- responsible for voluntary movements
- located in the frontal lobe of BOTH brain hemispheres
- different parts of the motor cortex control different parts of the body
- these areas are arranged logically next to one another
- damage to this area can cause a loss of
muscle function/paralysis in one or both sides of the body - depends on which hemisphere/hemispheres have been affected
5
Q
What does the somatosensory cortex do?
A
- responsible for processing sensations such as pain and pressure
- is located in the parietal lobe of BOTH hemispheres
6
Q
What does the visual cortex do?
A
- processes information such as colour and shape
- is in the occipital lobe of BOTH hemispheres of the brain
- visual processing starts in the retina where light enters and strikes the
photoreceptors - nerve impulses from the retina are transmitted to the brain via the optic nerve
- majority terminate in the thalamus, which acts as a relay station, passing the information onto the visual cortex
7
Q
What does the auditory cortex do?
A
- processes information such as pitch
and volume - lies within the temporal lobe in BOTH hemispheres of the brain.
- auditory pathway begins in the cochlea in the inner ear
- where sound waves are converted to nerve impulses
- which travel via the auditory nerve to the auditory cortex
- basic decoding occurs in the brain stem
- the thalamus carries out further processing before impulses reach the auditory cortex
8
Q
What does Broca’s Area do?
A
- area is named after Paul Broca who treated patients who had difficulty producing speech
- found that they had lesions to the LEFT
hemisphere of the frontal lobe - damage to the Broa’s Area causes Expressive Aphasia
- disorder affects language production but NOT understanding
- speech lacks fluency and patients have difficulty with certain words which help
sentences function like ‘it’ and ‘the’
9
Q
What does Wernicke’s Area do?
A
- area is in the LEFT hemisphere of the temporal lobe
- Carl Wernicke found that patients with a lesion to this area could speak but
were unable to understand language - Wernicke concluded that this area is
responsible for the processing of spoken language - Wernicke Area is connected to the Broca’s Area by a neural loop
- damage to the Wernicke’s Area causes Receptive Aphasia
- disorder leads to an impaired ability to
understand language
10
Q
Localisation of function, +ve evaluation:
A
- OCD sufferers underwent brain procedures to help reduce symptoms
- not only are certain brain areas responsible for symptoms of OCD
- but that an improved understanding of localisation of brain function has practical applications in the development of more advanced treatments for serious mental disorders
= was demonstrated, using PET scans, that semantic memories were recalled from the left prefrontal cortex
= whilst episodic memories were recalled from the right prefrontal cortex
= shows that different areas of the brain are responsible for different functions, as predicted by localisation theory
= idea was further supported by Petersen et al (1988)
= found that Wernicke’s area activation is required for listening tasks
= whereas Broca’s area is required for reading tasks
= confirms the idea that Wernicke’s area is involved in speech comprehension, whilst Broca’s area is responsible for speech production
11
Q
Localisation of function, -ve evaluation:
A
no +ve
- some functions are more localised than others
- motor and somatosensory functions are highly localised to specific areas of the cortex
- higher functions, e.g. personality and consciousness, are much more widely distributed
- functions such as language are too complex to be assigned to just one area - instead involve networks of brain regions
- although some components of
language, such as speech production, may be localised, Broca’s Area
= equipoteniality theory (Lashley, 1930)
= holds that higher mental functions are
not localised
= theory also claims that intact areas of the cortex take over responsibility for a specific cognitive function following injury to the area normally responsible
- Dronkers et al. (2007) re-examined the preserved brains of two of Broca’s
patients
- MRI scans revealed that several areas of the brain had been damaged
- lesions to the Broca’s Area cause temporary speech disruption
- they do not usually result in severe disruption of language
- language is a more widely
distributed (and less localised) skill than originally thought
= may be that how brain areas communicate with each other is more
important than specific brain regions
= Dejerine (1892) reported a patient who
could not read because of damage between the visual cortex and Wernicke’s area
- Bavelier et al. (1997) found that there are individual differences in which
brain areas are responsible for certain functions
- found that different brain areas are activated when a person is engaged in silent reading
- observed activity in the right temporal lobe, left frontal lobe and occipital
lobe
- means that the function of silent reading does not have a specific
location within the brain
12
Q
What is hemispheric lateralisation?
A
- refers to the notion that certain functions are principally governed by one side of the brain
13
Q
What is the main function of the right hemisphere?
A
- dominant for visuo-spatial functions and facial recognition
14
Q
What is the main function of the left hemisphere?
A
- demonstrated that in most people language centres are lateralised to the left hemisphere
- Broca’s Area was thought to be
responsible for the production of speech - however, this is now thought to
involve a wider network than just the Broca’s Area - damage to the Broca’s Area leads to expressive aphasia
- Wernicke’s Area is considered to play a
vital role in understanding language/interpreting speech - damage to the Wernicke’s Area leads to receptive aphasia
15
Q
How are the 2 hemispheres connected?
A
- connected by a bundle of nerve fibres known as the corpus callosum
- enables information to be communicated between the two hemispheres
- many researchers suggest that the two hemispheres work together to form most tasks as part of a highly integrated system
16
Q
Hemispheric lateralisation, +ve evaluation:
A
- makes sense from an evolutionary perspective
- increases neural processing capacity, which is adaptive
- using one hemisphere to engage in a particular task it leaves the other hemisphere free to engage in another function
- Rogers et al. (2004) found that hemispheric lateralisation in chickens is associated with an ability to perform two tasks simultaneously
- finding food and being vigilant for
predators
= patients who have extensive damage to their left hemisphere can experience
global aphasia (loss of speech production and speech comprehension)
= this suggests that language is lateralised to the left hemisphere
17
Q
Hemispheric lateralisation, -ve evaluation:
A
- lateralisation patterns shift with age
- research found that patterns of lateralisation can change with age, with many cognitive tasks becoming less lateralised in healthy adults as they get older
- suggests that the brain may rely on both hemispheres more equally in later life, which challenges the idea that certain functions are permanently confined to one hemisphere
- also implies that lateralisation is more flexible and influenced by developmental changes rather than fixed
- weakens the argument that hemispheric lateralisation is a stable and universal feature of brain organisation, as it appears to decline with age
= JW (a split-brain patient) developed the capacity to speak using his right
hemisphere
= they could speak about information presented in either the left visual field or the right visual field, although he was more fluent if information was presented in the left
= would appear that language is not lateralised entirely to the left hemisphere - if one hemisphere is damaged, undamaged regions on the opposite hemisphere can compensate
- Danelli reported case of EB
- 17y/o Italian boy w entire left hemisphere removed at the age of
two and a half due to a huge benign tumour - EB’s language appeared almost
normal in everyday life in terms of vocabulary and grammar - but systematic testing revealed subtle grammatical problems as well as poorer than normal scores on picture naming
- and reading of loan words, words adopted from another language e.g. café
- language function can be largely preserved after removal of the left hemisphere in childhood
- but the right hemisphere cannot
provide, by itself, a perfect mastery of each component of language
18
Q
What are split brain patients?
A
- in the past surgeons have cut the corpus callosum
- in order to prevent the violent electrical activity caused by epileptic seizures crossing from one hemisphere to the other
- patients who underwent this form of surgery are often referred to as split-brain patients
19
Q
What is the issue with split brain patients?
A
- Sperry and Gazzaniga investigated SB patients, dot and dog tests
- information from the left visual field goes into the right hemisphere
- whereas information from the right visual field goes into the left hemisphere
- in split-brain patients the corpus callosum has been severed
- there is no way for the information presented to one hemisphere to travel to the other
20
Q
How to investigate SB patients, dot?
A
- patients are asked to stare at a dot in the centre of a screen
- then information is presented in either the left or right visual field
- they are then asked to make responses with either their left hand (right hemisphere), right
hand (left hemisphere) - or verbally (left hemisphere)
- without being able to see
what their hands were doing
21
Q
How to investigate SB patients, dog/cat?
A
- may be flashed an image of a dog in their right visual field and then asked what they have seen
- they will be able to answer ‘dog’ because the information will have gone into their left hemisphere where the language centres are
- if a picture of a cat is shown in their left visual field and they are asked what they have seen
- they will not be able to say because the information has gone into their right hemisphere, which has no language centres
- but they can draw a picture of a cat with their left hand because the right hemisphere controls
this hand
22
Q
Split brain research, +ve evaluation:
A
- experiments on split-brain patients are highly controlled and scientific
23
Q
Split brain research, -ve evaluation:
A
- disconnection between the hemispheres was greater in some patients than others
= some split-brain patients have experienced drug therapy for much longer than others - comparison groups were not considered to be valid as they were often people with no history of epileptic seizures
= many studies using split-brain patients have as few as three participant
= making it hard for results to be generalised to the target pop - data from this research is very artificial
- in real world a severed corpus callosum can be compensated for by the unrestricted use of both visual fields
- means the research lacks ecological validity
24
Q
What is brain plasticity?
A
- brain’s ability to physically and functionally adapt and change in response trauma, new experiences and learning
- ability of the brain to modify the structure and function
based on experience - allows the brain to cope better with the indirect effects of brain damage!!!!!!
- such as swelling or haemorrhage following a road accident
- or the damage resulting from inadequate blood supply following a stroke
25
Brain plasticity, +ve evaluation:
no -ve
- Kuhn et al. (2014) found a significant increase in grey matter in the hippocampus, visual cortex and cerebellum of the brain after participants
played video games for 30 minutes a day over a two-month period
= Davidson et al. (2004) demonstrated the permanent change in the brain generated by prolonged meditation
= Buddhist monks who meditated frequently had a much greater activation of gamma waves, which coordinate neural activity
= than students who had no experience of meditation
- Maguire et al. (2000) found that the posterior hippocampal volume of London Taxi drivers’ brains was positively correlated with their time as a taxi driver
- there were significant differences between taxi drivers’ brains and those of a control group
26
what is functional recovery?
- the ability of the brain to transfer the functions of areas damaged through trauma, to other healthy parts of the brain, thus allowing for normal functioning to carry on
- where the brain recovers abilities previously lost due to brain damage
- is an example of plasticity
- enabled through the law of equipotentiality, where secondary neural circuits surrounding the damaged area become activated
- research suggests that young brains are more plastic
- however, the brain is capable of plasticity and functional recovery at any age
- studies have suggested that women recover from a brain injury quicker than men do
27
What processes does functional recovery involve?
- neuronal unmasking
- neural reorganisation
- neural regeneration
28
What is neuronal unmasking, FR?
- dormant synapses are activated to compensate for damaged areas of the brain
- structural changes support neuronal unmasking
- such as axon sprouting, when undamaged axons grow new
nerve endings to reconnect the neurons whose links were severed by damage thus making new neural pathways
- reformation of blood vessels, facilitates the growth of new neural pathways
- and recruitment of homologous areas, the intact hemisphere takes over the functions of the
damaged hemisphere
29
What is neural reorganisation, FR?
- transfer of functions from damaged areas of the brain to undamaged ones
- neural reorganisation is greater in children than in adults
30
What is neural regeneration, FR?
- growth of new neurons and/or connections, axons and dendrites
- to compensate for damaged areas
31
How does recovery work, FR?
- full recovery is not passive
- it depends on the extent of the damage and on various internal and external factors over time
- spontaneous recovery from a
brain injury tends to slow down after a number of weeks so treatment like physiotherapy
- may be required to maintain improvements in functioning
32
Functional recovery, +ve evaluation:
- has practical applications to the field of neurorehabilitation
- understanding the processes of functional recovery has led to the development of techniques such as motor therapy
- and electrical stimulation of the brain to counter the negative effects and deficits in motor
and cognitive functions
- following accidents, injuries and strokes
33
Functional recovery, -ve evaluation:
- variable factors affect recovery after trauma
- research found that those
with a university education recover better from a brain injury
- going to university provides a cognitive reserve
- age is another important factor
- Elbert et al. (2014) concluded that the capacity for neural
reorganisation is much greater in children than in adults
- gender also has an impact, women are more likely to recover from a brain injury than men
- physical exhaustion/stress/alcohol can all impair functional recovery
= although after trauma the brain activates secondary neural circuits the brain can only ‘repair’ itself up to a specific point
= after which motor therapy or electrical stimulation is needed to increase recovery rates
= this suggests that functional recovery cannot be relied upon to reinstate normal function
34
How can the brain be studied?
- post mortem examinations
- fMRI, functional magnetic resonance imaging
- EEG, electroencephalogram
- ERP, event related potentials
35
What are post mortem examinations?
- psychologist may study a person who displays an interesting behaviour while
they are alive
- when the person dies, the psychologists look for abnormalities in the brain that might explain their behaviour
- post-mortem studies have found a link between brain abnormalities and psychiatric disorders
- e.g. there is evidence of reduced glial cells in the frontal lobe of patients with depression
36
What is fMRI?
- provides an INDIRECT
measure of neural activity
- uses magnetic fields and radio waves to monitor blood flow in the brain
- measures the change in the energy released by haemoglobin, reflecting activity of the brain (oxygen consumption)
- gives a moving picture of the brain
- activity in regions of interest can be compared during a base line task and during a specific activity
37
Post mortem examinations evaluation:
1+ allow for more detailed examination of anatomical and
neurochemical aspects of the brain than would be possible with other methods of studying the brain
+ have enabled researchers to examine deeper regions, such as the hippocampus and hypothalamus
1- may lack validity as people die in a variety of ways and at varying stages of disease
- also length of time between death and the post-mortem, and drug treatments, can all affect the
brain
2- very small sample sizes, as special permission needs
to be granted
- means the sample cannot be said to be representative of
the target population
- so it is problematic to generalise the findings to the wider population
38
fMRI evaluation:
1+ captures dynamic brain activity as opposed to a post-mortem examination which purely show the physiology of the brain
2+ have good spatial resolution, refers to the smallest feature that a measurement can detect
1- interpretation is complex and is affected by poor temporal
resolution, biased interpretation, and by the base line task used
2- research is expensive leading to reduced sample sizes which negatively impact the validity of the research
39
What are EEGs?
- EEGs record the electrical activity of the brain using electrodes placed on the scalp, showing overall brainwave patterns
- electroencephalogram DIRECTLY measures GENERAL neural activity in the brain
- usually linked to states such as sleep and arousal
- electrodes are placed on the scalp and detect neuronal activity directly below where they are placed
- differing numbers of electrodes can be used depending on focus of the research
- when electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG pattern
- EEG patterns of patients with epilepsy show spikes of electrical activity
- EEG patterns of those with brain injury show a slowing of electrical activity
40
EEGs evaluation:
1+ EEG is useful in clinical diagnosis
+ useful in epilepsy diagnosis, it can record the neural activity associated with epilepsy so that doctors can confirm the person is experiencing seizures
2+ useful in investigating the differenct characteristics in the stages of the sleep cycle
3+ cheaper than an fMRI so can be used more widely in research
1- have poor spatial resolution
41
What are ERPs?
- event related potentials are brainwaves that are triggered by specific sensory, cognitive, or motor events, measured using EEG
- electrodes are placed on the scalp (like in EEG).
- stimulus (e.g. a picture, word, or sound) is presented multiple times
- brain’s electrical response to that event is recorded and averaged
- this removes background brain activity and isolates the response to that specific stimulus
42
ERPs evaluation:
1+ can measure the processing of a stimulus even in the absence of a behavioural response
+ it is possible to measure ‘covertly’ the processing of a stimulus
2+ cheaper than an fMRI so can be used more widely in research
3+ have good temporal resolution, unlike fMRI
1- poor spatial resolution, unlike fMRI
2- only sufficiently strong voltage changes generated across the scalp are recordable
- important electrical activity occurring deeper in the brain is not recorded
- generation of ERPs tends to be restricted to the neocortex
