Biopsych Flashcards
Get an A star innit
What is a neuron?
Cells that conduct electrical impulses to and from the brain to the rest of the body
What is the PNS split into?
Somatic - Controls voluntary muscles and transmits sensory information from to CNS
Autonomic - Controls involuntary body functions
What does the autonomic nervous system contain?
Sympathetic - Aroused body to expend energy
Parasympathetic - Calms body to conserve and maintain energy
Function of the brain stem
Regulates automatic functions which are necessary for life
Outline the role of the sensory neuron
To carry signals from receptors to the spinal cord and brain
Outline the role of the relay neuron
To carry messages from one part of the CNS to another
Outline the role of the motor neuron
To carry signals from CNS to effectors
Outline the process of synaptic transmission
-Nerve impulse arrives
-Causes vesicles containing the neurotransmitters to be released to fuse with the surface of the pre-synaptic membrane
-The neurotransmitter gets released into the synapse and diffuse across the synapse
-neurotransmitters bind to receptors on the post synaptic neuron causing the cell to fire or inhibit its action potentials depending on what neurotransmitter binds
What is an excitatory neurotransmitter?
Make it more likely that the next neuron will fire E.g. Glutamate
What is an inhibitory neurotransmitter?
Make it less likely the next neuron will fire E.g. serotonin
Explain summation
An excitatory neurotransmitter will produce an EPSP (excitatory post synaptic potential) where as an inhibitory neurotransmitter will produce an IPSP (inhibitory post synaptic potential). Whether or not the post synaptic neuron is fired or not will depend on the balance of IPSP and EPSP. If the threshold is reached (EPSP>IPSP) the neuron will fire.
If IPSP>EPSP then no threshold is reached so the neuron doesn’t fire
What is the endocrine system?
A collection of glands which produce hormones
Outline the role of the pituitary gland
-‘Master gland’
-Causes other glands to release hormones
-Made of 2 parts; anterior and posterior. They both release different hormones.
Anterior releases Luteinizing hormone (LH) and follicle stimulating hormone (FSH)
-Posterior pituitary gland releases oxytocin
Outline the role of the adrenal glands
Adrenal cortex - Outer part, produces hormones which are crucial for life. E.g. CORTISOL which promotes normal metabolism and maintains blood sugar levels.
Adrenal medulla - Inner part, Produces hormones which aren’t crucial for life. E.g. fight or flight. Adrenaline helps the body respond to stressful situations.
Outline the role of the ovaries
Responsible for the production of eggs and for the production of estrogen an progesterone. Estrogen prevents action of FSH and is involved in puberty.
Progesterone is more important in maintenance of pregnancy. Prevents womb contracting before labour
Outline the role of the testes
Produces testosterone which is responsible for growth of facial hair, deepening of voice, growth spurts, sex drive, sperm production and maintenance of muscle mass
Explain the fight or flight response
-Amygdala signals to the hypothalamus when stress is detected
-The hypothalamus sends a stress signal to the sympathetic nervous system which is part of the autonomous nervous system
-SNS sends a signal to the adrenal medulla
-Adrenal medulla releases the hormone adrenaline into the blood stream
-Adrenaline causes a number of physiological responses ;Digestion suppression, sweating, increases heart rate, increased breathing rate and pupil dilation
-Once the threat has passed, the parasympathetic system brings the body back to normal again
Outline features of the visual cortex
-Located in the occipital lobe
-Visual processing begins in the retina (light enters and strikes the photoreceptors (rods and cones))
-Nerve impulses from the retina travel t the brain via the optic nerve
-Visual cortex spans both hemispheres
-The right hemisphere receives input from the left hand side of visual field.
Outline features of the auditory centers
-Hearing
-Located in the temporal lobe
-Begins in the cochlea (inner ear), sound waves are converted into nerve impulses
-These travel via the auditory nerve to the auditory cortex
Outline features of the motor cortex
-Located in frontal lobe
-Responsible for generation of voluntary motor movements
-located in frontal lobe along the bumpy region
-On both hemispheres motor cortex on the right hemisphere controlling muscles on the left hand side of the body
-Different parts of the motor cortex control different parts of the body
Outline features of the somatosensory cortex
-Detects sensory events from different regions of the body
-Located in the parietal lobe
-Dedicated to the processing of sensory information, related to touch
-Uses sensory information from skin to produce sensations such as touch, pressure, pain, temperature which it localizes to specific body regions
-Both hemispheres have a somatosensory cortex
-Cortex on one side receives information from the opposite side of the body
Outline the features of the Broca’s region
-Patients with damage to Broca’s region had trouble with speech
-People with damage to their right frontal hemisphere didn’t have this problem
-This lead to the identification of a language cortex in the back portion of the frontal lobe on left hemisphere
-Critical for speech production
-HOWEVER, NEUROSCIENTISTS HAVE FOUND THAT WHEN PEOPLE FERFORM COGNITIVE TASKS, THEIR BROCA IS ACTIVE
Outline the features of the Wernicke’s area
-Located in the back portion of the temporal lobe
-Patients with lesions on their Wernicke’s area could speak but were unable to understand language
-Proposed that language involved separate motor and sensory regions
-The motor region is close to the area that controls the mouth, tongue and vocal cords
-The sensory region, located in Wernicke’s area is close to the regions of the brain responsible for auditory and visual input
AO3
Outline one strength of localization of brain function
(Real life application, brocas region)
One strength of localization of brain function is that it has real life application.
For example, women are better than men at speaking, science has proven that women have a larger Broca’s area than men.
This means localization of brain function has real life applications thus strengthening our acceptance of localization of brain function as it has proven to have real life application and been proven by science
AO3
Outline one weakness of localization of brain function
(Lashley’s research)
-One weakness of localization of brain function is that it has contradicting research from Lashley.
-Lashley removed areas of the cortex in rats that were learning a maze, he found that no area was proven to be more important than any other area in terms of the rats ability to learn the maze. Processing learning appeared to require every part of the cortex rather than being confined to a particular region.
-This suggests higher cognitive functions such as learning are not localized but distributed in a more holistic way in the brain.
-This weakens our acceptance of localization of brain function as it has been contradicted by research from Lashley
AO3
Outline one weakness of localization of brain function
(Plasticity)
-One weakness of localization of brain function is that there is the concept of plasticity.
-When some of the brain has been damaged and a particular function has been lost, other parts of the brain can take over the function. For example, several stroke victims have been able to recover these abilities that were seemingly lost as a result of illness
-The law of equipotentiality suggests that surviving brain circuits ‘chip in’ so the same neurological action can be achieved.
This suggests learning is too complex to be localized and this weakens our acceptance of the theory .
What is the right side of the brain responsible for?
Visual motor tasks - Creativity, art and music
What is the left side of the brain responsible for?
Dominant for language - Science, maths and language
What condition needs to be met for a nerve impulse to occur, once the post-synaptic potential travels down to the cell body?
A nerve impulse occurs if multiple excitatory post-synaptic potentials summate in the post-synaptic neuron.
Sensory neurons carry information…
A) away from the brain.
B) both to and from the brain.
C) towards the brain.
D) within the brain.
C
The somatic nervous system…
A) comprises of two sub-systems.
B) connects the central nervous system and the senses.
C) consists of the brain and spinal cord.
D) controls involuntary responses.
B
What does the CNS consist of?
What does the PNS consist of?
Brain and spinal cord
All neurons outside the brain and spinal cord
Which one of the following responses results from the action of the sympathetic division of the autonomic nervous system?
A) Decreased pupil size
B) Increased digestion
C) Increased heart rate
D) Increased salivation
C
Function of the cerebellum
Controls posture and balance
Role of the sympathetic nervous system
-Involved in fight or flight response
-Prepares the body for stressful or emergency situations
- Increased heart rate, vasodilation, increased strength
Briefly explain one function of the endocrine system (2)
-To secrete the hormones which are required to regulate many bodily functions.
-To provide a chemical system of communication via the bloodstream.
Identify two glands that form part of the endocrine system and outline their functions (Total 4 marks)
-Adrenal glands: secretes adrenaline / controls the sympathetic division in the fight or flight response
-Thyroid gland: secretes thyroxine/increases metabolic rates and affects growth
Outline the role of adrenaline in the fight or flight response (Total 4 marks)
-Adrenaline is released from the adrenal medulla
-Helps the body respond to stressful situations as am evolutionary adaptation to aid survival
-Adrenaline has a range of effects on the body
-Increase heart rate
-Constricts blood vessels
Explain the two differences between the endocrine system and the nervous system
-The cells in the endocrine system group into clusters called glands, whereas the cells in the nervous system are called neurons.
-The endocrine system communicates via glands through hormones released into the bloodstream. On the other hand, the nervous system communicates through electrical signals sent from one neuron to the next
Differences between adrenal medulla and adrenal cortex
-The adrenal medulla releases adrenaline in response to stress but the adrenal cortex produces cortisol
-The adrenal medulla is the inside part but the adrenal cortex is the outer layer
Outline how communication occurs in the endocrine system
A stimulus causes the pituitary gland to release a hormone into the bloodstream, hormones travel around the bloodstream until they reach target cells and they bind to the receptors on the target cells, causing a response in the target cell
Outline Sperry’s split brain experiment
-Quasi experiment
-11 ppts
-Ppts were epileptics who could not be treated with drugs. Already had corpus callosums split. No ethical issues
-Ppts gazes at fixation point on a translucent screen
-Slides projected either side of fixation point at a rate of one image per 1/10 seconds
Findings of Sperry’s split brain experiment
When a picture of an object was shown to participants right visual field they could describe what was seen, when a picture was projected into the ppts left visual field they could not describe it. (Often report there was nothing there)
What are the limitations of split-brain research?
-The study has not been consistently replicated
-The study contains a confounding variable
-The participants’ brains were abnormal
-The study lacks generalisability
AO3
Weakness of lateralisation and split brain
(Language not restricted to one hemisphere)
One weakness of lateralisation and split brain theory is that language may not be restricted to the left hemisphere only as the theory suggests.
For example, research has suggested that damage to the left hemisphere is more detrimental to damage to the right hemisphere
However, one patient known as J.W developed the capacity to speak out of the RIGHT HEMISPHERE with the result that he can now speal about information presented to the left hemisphere or right side of the brain
AO3
Outline one weakness of lateralisation and split brain
(JW)
A case study of Gazzaniga called J.W. is an exception to the idea that speech is lateralised to the left hemisphere. He is a split brain patient that has learned to produce and understand speech using his right hemisphere as well as his left hemisphere. This provides direct evidence against the idea that the separate hemispheres have separate functions
AO3
Weakness of lateralisation and split brain research
(Problem of case studies)
One weakness of split brain research is that the case studies used in research use a very small sample
Split brain studies are rarely done today and those that have been done previously have as few as one or two ppts making up the study
Therefore this means we cant properly generalise the findings from one or two ppts to the wider population
Therefore this weakens our acceptance of this research as it can
AO3
Weakness of lateralisation
(Health implications)
-Creative people such as architects and mathematics have superior right hemispheric skills but are also much more likely to be left handed and have a weakend immune system
-Tonnesson found a link between handiness and immune system disorders suggesting that the same genetic process that lead to lateralisation may also affect the immune system
AO1
Outline the theory of brain plasticity
-Suggests the brain can change and adapt overtime
-In infancy the brain experiences growth in the number of synaptic connections it has peaking at around 15000 at age 2-3 years
-As we age, rarely used connections are strengthened in a process known as synaptic pruning
-Brain is more plastic when its younger meaning it is more capable to forming new synaptic connections.
AO1
Outline research into plasticity
Maguire et al (2000) studied the brains of London taxi drivers and found that they had significantly more volume of grey matter in the posterior hippocampus then a matched control group
The hippocampus is associated with navigational skills in humans and animals
AO1
Outline video game research into plasticity
-Kuhn (2014) got ppts to play super Mario for 30 minutes a day for 2 months and then compared brain development to a control group not playing video games
-Found ppts differences in grey matter of the video gaming ppts, particularly in the areas controlling fine movement control, spatial skills, and planning. Used brain scans
-Kuhn’s study found that learning is accompanied by plastic changes in the brain, like rewiring.
What are the 3 functional recoveries the brain does after trauma
Neural unmasking
Axon sprouting
Recruitment of homologous areas
Outline neural unmasking
The brain rewires and reorganises itself by forming new synaptic connections close to the damage
Secondary neural pathways that would not typically be used to carry out certain functions are activated or ‘unmasked’ to enable functioning to continue
Outline axon sprouting
Growth of nerve endings which connect with other undamaged nerve cells to form new neural pathways
Outline recruitment of homologous areas
When the same/similar area of the brain on the opposite side is used to perform a specific task
E.g. Jody miller - Right hemisphere was removed from her brain but she was still able to walk
AO3
Outline one strength of the theory of plasticity
(Research support from animals)
Researchers found an increased number of new neurons in the brains of rats who were in a maze comparted to rats in a cage
These rats had more neurons in their hippocampus, part of their brain responsible for memory but also the ability to navigate from one area to another
This provides clear evidence that the brain can change
AO3
Outline one strength of the theory of plasticity
(Those who finish school)
Schneider found that college graduates are 7x more likely to be disability-free after brain damage than those who didn’t finish high school and suffered with brain damage
Schneider argues that the ‘cognitive reserve’ is associated with educational attainment and is a crucial factor in functional recovery
Therefore this has useful applications - encouraging students to build up their ‘cognitive reserve’ through attending school
What are the 4 ways of measuring the brain?
-fMRI
-EEG
-ERPIs
-Post mortem examinations
AO1
Outline fMRIs
-Works by detecting changes in blood oxygenation and flow which occurs as a result of neural activity in specific parts of the brain
- Active brain areas consume more oxygen
-fMRI produces 3D images that are activation maps showing which areas are consuming more oxygen
AO3
Outline the strengths of using the fMRI
-Don’t use radiation like PET scans
-Non-invasive, risk-free and straight-forward to use
-Very high spatial resolution, giving very high detail
AO3
Outline weaknesses of fMRI
-Most expensive technique
-Poor temporal resolution, there is a 5 second lag between the image on screen and firing of neurons
AO1
Outline the EEG technique
-Measures electrical activity by fixing a skull cap on a head with electrodes
-The brain wave patterns are a representation of electrical activity/activity from neurons
-Used by clinicians to diagnose abnormalities
-Unusual arrhythmic patterns of activity can indicate neurological abnormalities
AO3
Outline the strengths and weaknesses of using the EEG technique
Strengths:
-Only technique which can diagnose abnormalities
-High temporal resolution
Weakness:
-Tend to produce very generalised information so it is not useful for pinpointing the exact source of neural activity
AO1
Outline the use of the ERPI technique
-Way of teasing out and isolating specific neural responses associated with sensory, cognitive and motor events
-Work by using a statistical averaging technique, that filters out extraneous brain activity from the original EEG
CERTAIN EVENTS OR THINGS PRODUCE CERTAIN BRAIN WAVES
(Louise Theroux’s Peedo documentary)
AO3
Outline the strengths and weaknesses of using the ERPI technique
Strengths:
-Excellent temporal resolution, measures it to the millisecond
-Addresses limitations of EEGs
Weaknesses:
-Not easy to carry out. To establish pure data in ERP studies, background noise and extraneous material can all affect the brain wave produced
AO1
Outline the Post-mortem examination technique
-Analysis of a person’s brain after death. E.g. HM had no hippocampus
-Those whose brains are subjected to a post-mortem are likely to be those who have a rare disorder
AO3
Outline strengths of post-mortem examinations
-Vital in providing a foundation for early understanding E.g. broca relied on PM studies in establishing links between language, brain and behaviour
-Provide medical knowledge
AO3
Outline weaknesses of post-mortem examinations
-Patients can’t give informed consent E.g. HM had research carried out on his brain and wasn’t able to provide consent
-Problems with cause and effect -If there are multiple areas of damage in the brain it is hard to know what caused what
Outline the circadian rhythm
-A biological rhythm which operates on a 24-hour cycle
-Our internal body clock drives the circadian rhythm
-Our body clock is constantly reset so that our bodies are in sync with the outside world
-Light provides the primary input, allowing our internal body clock to be set to the correct time
Outline the role melatonin plays in the circadian rhythm
-Melatonin is produced in the pineal gland in the brain, which chemically causes drowsiness and lowers body temperature
-Melatonin is highest at 2 am which is when we are in deepest sleep and body temp is lowest
Where is the circadian ‘clock’ located?
SCN - Suprachiasmatic nucleus
How does light influence the sleep/wake cycle?
Sensory receptors that detect light can send information directly to the SCN to influence melatonin release
AO1
Aschoff and Weber’s research
Evidence FOR endogenous pacemakers affecting circadian rhythm
-Put ppts in a ww2 bunker for 4 weeks and ppts were deprived of natural light
-All but one of these ppts had a circadian rhythm between 24 and 25 hours
-Both Siffre’s experience and bunker experiment suggest the ‘natural’ sleep wake cycle
-Aschoff & Weber made participants sleep in a bunker with no natural light.
-The participants had lamps.
Weaknesses of Aschoff and Weber’s study
-The participants still had access to some artificial light, which may have helped reset their circadian rhythm.
-The results may have underestimated the importance of light, and overestimated the importance of endogenous pacemakers.
Explain why the use of artificial light, in both Siffre’s and Aschoff & Weber’s studies, could be considered a limitation.
The artificial light used in these studies might have reset the body clocks of the participants. Therefore, if no artificial light was present participants might have had even greater irregularities in their circadian rhythms.
Explain Siffre’s cave study
(endogenous pacemakers exert an influence on circadian rhythms)
-Siffre conducted a case study
-Siffre lived in a cave for 6 months with no access to natural light
-Siffre’s sleep/wake cycle increased to a 25-30 hour cycle without access to light.
Findings of Ralph et al
-Transplanting the abnormal hamsters’ SCN into the normal hamsters caused them to adopt an abnormal 21 hour sleep/wake cycle.
-Transplanting the normal hamsters’ SCN into the abnormal hamsters caused them to adopt a normal 24 hour sleep/wake cycle.
-Both the abnormal and normal hamsters lost their sleep/wake cycle when their SCN was removed
Outline Ralph et al
(support for SCN)
-Ralph et al conducted a study investigating the sleep/wake cycle in hamsters
-Ralph et al had a control group with a normal sleep/wake cycle and an experimental group with an abnormal 21 hr sleep/wake cycle
-He removed the SCN in both hamsters and placed the abnormal hamster’s SCN into the normal hamster’s brain and vice versa
However, we cant generalise the findings to humans as human brain may operate differently to hamster brains
AO3
Outline one weakness of research into circadian rhythm
(Confounding variables)
One weakness of research into circadian rhythms is that they are affected by confounding variables
Although ppts are deprived of natural light, TV, clocks and radios, meant they weren’t deprived of artificial light because at the time, researchers didn’t believe artificial light would have an effect on circadian rhythm
Later research suggested this may not be true. This suggests that there is no way of establishing cause and effect as there were uncontrolled confounding variables which could have afected the outcome of the study.
Therefore this weakens acceptance of research as there are problems with establishing cause and effect
AO3
Outline strength of research into circadian rhythm
(Real world drug application)
-The use of chronotherapeutic can be life saving to patients who need drug medication
-The specific time a patient takes a drug is crucial to its effectiveness. For example, heart attacks are more common during the early hours of the morning
-A new drug system using chronotherapeutic has been invented - the patient takes the drug at 10 pm but the drug is not actually active until 6am - the most likely time a heart attack would occur
-Our predictable circadian rhythm has allowed this treatment to be successful we know people biologically will wake up at around that time with little variation
AO3
Outline a weakness of research into circadian rhythm
(Temperature)
-Buhr argues that temperatures controls our body clock rather than light
-Although light is undoubtedly the trigger, the SCN transforms this info into neural messaging that set the body temp
-Body temp fluctuates over a 24 hour period an even the smallest change to our body temperature can be enough to massively influence our internal body clock and cause tiredness
What is an ultradian rhythm?
A biological rhythm which has a cycle shorter than 24 hours
What is an infradian rhythm?
A biological rhythm which has a cycle of more than 24 hours
What are the five stages of sleep and what is one characteristic of each stage
Stage 1 - Light sleep - Muscle activity slows down
Stage 2 - Light sleep - Breathing and heart rate slow down. Body temperature decreases
Stage 3 - Deep sleep begins - Brain starts to generate slow delta waves
Stage 4 - Very deep sleep - Rhythmic breathing, limited muscle activity
Stage 5 - REM sleep - Brainwaves speed up. Heart rate increases. Breathing is rapid. Atonia (paralysis of muscles) - As the night progresses, REM sleep increases towards the 4-5th cycle
Outline features of beta brain waves
During full wakefulness - high frequency - no reliable pattern
Outline features of delta waves
Deep NREM sleep. Activity dramatically decelerates. Ten times slower than wakefulness. Highly predictable in pattern
Outline features of theta waves
Almost identical to the frequency we have during full wakefulness - the brain seems awake but the body is asleep. Emotions, motivations, and memories are played out like a movie. Hence dreaming occurs
AO3
Outline one strength of the theory of ultradian rhythms
(Supporting research EEGs)
+Counter argument
Dement and Kleiman monitored the sleep patterns of 9 adult ppts in the sleep lab.
Brain wave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol.
They found that REM sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid the dreams were, and ppts woken during their dream reported very accurate recall of their dreams
This suggests that the REM stage of sleep is associated with dreaming and that this is distinct from other stages In the ultradian rhythm, which is what coincides with the theory of ultradian rhythms, strengthening acceptance of the theory
HOWEVER…
It has been found that not all dreams happen during the REM sleep stage of the cycle e.g. hypnogogic dreams occur during stages 1 and 2 of sleep cycle
AO3
Outline one strength of infradian rhythms
(Irregular periods)
McClintock studied 29 women with a history of irregular periods. Samples of pheromones were gathered from 9 of the women at different stages of menstrual cycle via a cotton pad to be rubbed on the upper lip of other ppts.
Found that 68% of women experienced changes to their cycle which brought them closer to the cycle of their odour donor
This indicates that the menstrual cycle is influenced by exogenous factors
AO3
Outline one strength of infradian rhythms
(RWA)
One strength of infradian rhythms is they have real life applications.
For example, research into seasonal affected depression suggests that SAD is due to the SCN not receiving sufficient amounts of light.
This suggests through understanding infradian rhythms, we can better explain seasonal affected depression, thus strengthening our acceptance of the theory
Outline features of stage 1 sleep
Light sleep
Muscle activity slows down, preparing us for sleep
Outline features of stage 2 sleep
Light sleep
Breathing and heart rate slows down and body temp decreases
Outline features of stage 3 sleep
Deep sleep begins
The brain starts to generate slow delta waves
Outline features of stage 4 sleep
Very deep sleep
Rhythmic breathing, limited muscle activity
Outline features of stage 5 sleep
REM sleep. Brainwaves speed up, heart rate increases, atonia of muscles
Identify two glands that form part of the endocrine system and outline their functions (Total 4 marks)
Adrenal glands: secretes adrenaline / controls the sympathetic division in the fight or flight response
Thyroid gland: secretes thyroxine/increases metabolic rates and affects growth
Explain how synaptic transmission occurs at the synapse.
When a nerve impulse arrives at the pre-synaptic terminal, the pre-synaptic neuron releases neurotransmitters into the synaptic cleft. These neurotransmitters travel across the synaptic cleft and bind to receptors on the post-synaptic membrane, allowing charged particles to flow into the neuron. The charged particles create a change in voltage, leading to either an excitatory post-synaptic potential or an inhibitory post-synaptic potential, depending on whether the neurotransmitter is excitatory or inhibitory.
Describe two ways synapses can be strengthened, and how this affects the likelihood of nerve impulses being transmitted.
Firstly, the number of neurotransmitters released by the pre-synaptic neuron can be increased, which means that more neurotransmitters bind to post-synaptic receptors, allowing more charged particles into the post-synaptic neuron.
Second, the number of receptors available to pick up neurotransmitters on the post-synaptic neuron can be increased. This also means that more neurotransmitters bind to post-synaptic receptors, which again means there are more charged particles in the post-synaptic neuron.
Both of these mechanisms lead to an increase in the likelihood of nerve impulses being transmitted between the two neurons, meaning that the synapse has been strengthened.
AO3
Outline one weakness of Maguire’s research into plasticity
(ppts variables)
One weakness of Maquire’s study is that it was a quasi experiment. For example, Maquire couldn’t control participant variables by randomly allocating participants to groups.
This suggests there may be unknown participant variables (e.g. taxi drivers have a very social job) which may have affected the size of the taxi drivers hippocampus. Therefore this weakness acceptance of Maquire’s research into plasticity as there is a lack of control over participant variables
AO3
Outline one weakness of Maguire’s research into plasticity
(Causation)
One weakness of Maquire’s research into plasticity is that we can’t establish cause and effect. For example, these taxi drivers may have had a large hippocampus, which is why they became taxi drivers to begin with. This suggests we cannot understand causation as there was no brain scan imaging for the taxi driver’s brain prior to the experiment, so there is no way of telling if being a taxi driver caused increased hippocampus volume in taxi drivers.
Therefore this weakens acceptance of the research as there is no way of understanding causation
In Sperry’s original study, he showed split-brain patients a stimulus, to either their right or left hemisphere. He then later asked patients to point to that same stimulus, when showed a choice of four different ones. Patients could point to the correct image. Explain why this happened.
The ability to visually process and identify the image isn’t hemispherically lateralised. Therefore regardless of which hemisphere the information was presented, the participant had still processed the information and could point to the correct stimulus from the choice of four.
When participants were asked to respond verbally to a stimulus, their response depended on which side the information was presented to. Explain why these results occurred in Sperry’s subsequent study.
The ability to say what was processed by the left hemisphere occurred because language is hemispherically lateralised to the left hemisphere. If a stimulus is presented to the right hemisphere, a split-brain patient is unable to identify or describe it, because language is not processed in the right hemisphere.
3 weaknesses of split-brain research
-First, it only involves a small number of patients with brain abnormalities so the research may lack generalisability
-Second, because patients have brain abnormalities, this may act as a confounding variable.
-Finally, not all findings on hemispheric lateralisation have been replicated: for instance, more recent studies have shown that not all aspects of language are controlled by the left hemisphere.
AO3
Outline one weakness of hemispheric lateralisation
(Patient EB)
One weakness of hemispheric lateralisation is that there is research evidence from patient EB which contradicts this theory
For example, patient EB had a tumour on his left hemisphere when he was 2.5 years old and he lost all of his language skills. However, by age 8, he had regained his language skills. Researchers found that when EB spoke, his right hemisphere was active, meaning EB’s right hemisphere had taken over the function of language, suggesting that there are exceptions to hemispheric lateralisation which the theory doesn’t account for, thus weakening acceptance of hemispheric lateralisation.
AO3
One weakness of using split brain patients
(confounding variables)
It is possible that there are confounding variables within the study that would jeopardise the validity of his conclusions. It may be that epileptic seizures or the drugs used to treat epilepsy caused this effect, and not the absence of the corpus callosum. Therefore this is a confounding variable in the interpretation of the study, because it may actually be the drugs or seizures that cause any results rather than their corpus callosum being severed, as Sperry suggests, therefore this jeopardizes the validity of the findings
For vision, touch, and movement, each hemisphere controls the opposite side of the body, so they are organised …
CONTRLATERALLY
