biological approach: the relationship between the brain and behaviour Flashcards
(106 cards)
1
Q
MRI (what is it)
A
- An MRI scanner uses a magnetic field and radio waves to map the activity of hydrogen molecules.
- Hydrogen molecules are present in different brain tissue to different degrees.
- A static image is created through a compilation of many snapshots of the brain.
- The image can either be viewed as a two-dimensional slice of the brain from any angle or it can be used to create a three-dimensional images of brain structures.
- The images show the structure of the brain however don’t give any indication of brain function.
2
Q
MRI (s&w)
A
S- It enables researchers to pinpoint specific brain structures which may be damaged or have increased grey matter to identify the link between brain and behaviour
W- MRI scanners are prone to disturbance caused by noise, temperature and human error in calibration, which means that they are not always reliable
3
Q
fMRI (what is it)
A
Measures oxygenated blood flow in the brain i.e. brain activity
4
Q
fMRI (s&w)
A
S- It enables researchers to measure oxygenated blood in specific brain regions which can inform them of brain activity linked to cognitive processes such as emotion
W- fMRI is slow, having a 5-second delay between brain activity and measurement and so it may miss some important information. Low temporal resolution
5
Q
study: Maguire (2000) AIM
A
aimed to investigate neuroplasticity and localisation of function in the brain.
6
Q
study: Maguire (2000) METHOD
A
Maguire looked at MRI scans of right-handed male taxi drivers who had passed ‘The Knowledge’, a test of spatial navigation and who had been driving for at least 18 months.
She compared these to pre-existing MRI scans of 50 healthy, right-handed males who were not taxi drivers, they served as a control group.
7
Q
study: Maguire (2000) RESULTS
A
Maguire found that the posterior hippocampus of the taxi drivers showed a greater volume of grey matter than that of the non taxi drivers, who had increased grey matter in their anterior hippocampus compared to the taxi drivers.
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Q
study: Maguire (2000) CONCLUSION + LINK
A
This supported the theory of localisation of function as only certain areas of the brain were affected by being a taxi driver.
She used voxel-based morphometry (VBM) which focuses on the density of grey matter from MRI scans to find a positive correlation between volume of posterior hippocampal grey matter and length of time spent as a taxi driver.
This supported the theory of neuroplasticity as the brain changed as a response to an external stimuli.
Overall, Maguire’s study shows how brain imaging techniques such as the MRI can be used to study the brain and behaviour.
9
Q
study: Maguire (2000) STRENGTH
A
- Highly controlled clinical method of obtaining objective data, this could then be easily compared and analysed
- Understanding neuroplasticity can help aid the recovery of people who have suffered brain damage
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Q
study: Maguire (2000) WEAKNESS
A
- A correlation can’t show cause-and-effect so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
- Results are only generalisable to male, right-handed London taxi drivers, so the nature of neuroplasticity in women is not known
11
Q
study: Fisher et al (2005) AIM
A
to investigate the brain systems involved in early-stage intense romantic love
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Q
study: Fisher et al (2005) METHOD
A
- 10 females, 7 males from NY state university (self-selecting sample), mean age 20, all participants reported being ‘in love’ for a mean range of 7 months
- Participants placed in an fMRI scanner and shown a photograph of their loved one, followed by a distraction task, then a ‘neutral’ photograph of an acquaintance with whom they had a non-emotional relationship
13
Q
study: Fisher et al (2005) RESULTS
A
- when the participants viewed the photograph of their loved one, specific areas of their brain were active: the right ventral tegmental areas and the right caudate nucleus. - Both these areas are strongly associated with dopamine activation (a neurotransmitter which induces a feeling of reward and motivation in people)
14
Q
study: Fisher et al (2005) CONCLUSION
A
- results suggest that people in the early, intense stages of romantic love access the areas of the brain most associated with motivation and reward, giving rise to the idea that people may become ‘addicted to love’
- Dopaminergic reward pathways may contribute to the ‘general arousal’ component of romantic love, making it a biological process rather than a cognitive one
15
Q
study: Fisher et al (2005) STRENGTHS
A
- Standardised procedure → study is replicable, increases its reliability
- Use of fMRI means that the study was able to support to the idea that human beings may have evolved a brain system which ensures that they become addicted to love, increasing the validity of the study
16
Q
study: Fisher et al (2005) WEAKNESSES
A
- Small sample size of 17 participants means that the results are not very meaningful, may not be robust in terms of statistical analysis
- Idea that romantic love can be measured via fMRI is overly reductionist → may be a range of other factors involved e.g. compatible personalities, shared ideals, cultural influences
17
Q
localisation
A
the idea that different regions of the brain are responsible for different functions or behaviours
18
Q
the brain
A
- the most complex part of the body
- responsible for higher level mental functions such as thinking, sensation and behaviour
19
Q
right hemisphere
A
- responsible for emotion, creativity and belief
- controls the left side of the body.
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Q
left hemisphere
A
- responsible for logic, language and problem solving
- controls the right side of the body
21
Q
cerebral cortex
A
- outer structure of the brain
- split up into 4 lobes: frontal, parietal, occipital, temporal
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Q
occipital lobe
A
vision
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Q
parietal lobe
A
higher senses and language functions
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Q
frontal lobe
A
movement, cognition, decision making and reasoning
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temporal lobe
hearing memory and meaning
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Broca's area
- found in the left frontal lobe
- responsible for language production
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Wernicke's area
- found in the left temporal lobe
- responsible for language comprehension
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limbic system
- controls the basic emotions (fear, pleasure, hunger) and drives (hunger, sex)
- amygdala, thalamus, hypothalamus, hippocampus
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thalamus
sensation
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hippocampus
involved in memory and learning
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hypothalamus
- regulates bodily functions
- controls the pituitary gland
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amygdala
anger, fear, emotion
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cerebellum
coordinates and regulates muscular activity and balance
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brain stem
- connects brain to spinal cord
- involved in regulating automatic functions e.g. breathing, temperature
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study: Broca's case study of Tan AIM
- to investigate the localisation of language production to a specific area of the brain
- he did this to find an explanation for Tan’s unusual circumstance of being unable to produce speech
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study: Broca's case study of Tan METHOD
- Broca observed Tan over the course of a number of years and after Tan’s death
- he conducted an autopsy on Tan’s brain.
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study: Broca's case study of Tan RESULTS
- this revealed a lesion in an area in the left frontal lobe, providing Broca with evidence that language production is localised to this area, now called Broca’s Area
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study: Broca's case study of Tan CONCLUSION
- language production can be localised to the left frontal lobe in ‘Broca’s area’
- If damage occurs in this area, it results in Broca’s aphasia (inability to produce coherent speech)
- Therefore, this supports the localisation of function as language production has been localised to a specific area of the brain- Broca’s area.
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study: Broca's case study of Tan LINK/SUMMARY
- Localisation of function has therefore been proven by Broca
- His study showed that a specific part of the brain, Broca’s area, was responsible for a specific function, language production.
- Localisation of function was also shown as when this specific region was damaged, the specific function that area performs was inhibited.
- In this case, when Broca;s area was damaged, language production was inhibited
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study: Broca's case study of Tan STRENGTHS
- Longitudinal nature → full, in-depth investigation into the individual and their condition was possible
- Tan’s case highlighted important new insight into the brain and its link to language and speech production
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study: Broca's case study of Tan WEAKNESSES
- Very dated research, a modern researcher could use a range of brain-imaging techniques to isolate the brain region involved in the condition
- May have been other explanations for Tan’s speech impairment which were not explored at the time
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study: Maguire (2000) AIM
to investigate localisation of function linked to spatial navigation experience in London black cab taxi drivers
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study: Maguire (2000) METHOD
- 16 healthy, right handed male London black cab taxi drivers who had passed ‘The Knowledge’, a test of spatial navigation, aged 32-62, all taxi drivers for at least 18 months. - Participants were placed in an MRI scanner and their brains were scanned.
- MRI measured the volume of grey matter in the hippocampus of each participant.
- This was compared to pre-existing scans of 50 healthy right handed males (control). - - Grey matter was measured using voxel-based morphometry (VBM), this focuses on the density of grey matter and pixel counting
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study: Maguire (2000) RESULTS
- posterior hippocampus of the taxi drivers showed a greater volume of grey matter than that of the controls, who had increased grey matter in their anterior hippocampus compared to the taxi drivers.
- Maguire also carried out correlational analysis which showed a positive correlation between volume of posterior hippocampal grey matter and length of time spent as a taxi driver
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study: Maguire (2000) CONCLUSION
the posterior hippocampus may be linked to spatial navigation skills
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study: Maguire (2000) STRENGTHS
- Use of MRI technology means that the researchers were able to pinpoint the key area of the brain localised to spatial navigation
- The correlational analysis of time spent as a taxi driver linked to increased volume of hippocampal grey matter lends validity to the idea of neuroplasticity due to learning and experiences
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study: Maguire (2000) WEAKNESSES
- A correlation can’t show cause-and-effect, so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
- MRI technology is not 100% reliable as it is vulnerable to noise, temperature and operator-error
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localisation of function critical thinking
- Localization research is often limited to very specific behaviours, for example, spatial memory, habits, etc. Memory as a whole is distributed throughout the brain.
- Most of the research is of two types - animal research, in which direct manipulation of an IV can be carried out through lesioning - or correlational research, such as many of the quasi-experiments that are done. - Some of the studies above also are drawing indirect conclusions - e.g. Draganski and Maguire - about the specific role of certain areas of the brain.
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neuroplasticity
- refers to the brain’s ability to alter its own structure following changes within the body or in the external environment
- these changes can occur as a result of genetics, experience, learning or brain injury/damage
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structural plasticity
refers to changes within brain structures (e.g. the hippocampus) due to learning experienced over time i.e. this does not happen immediately
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functional plasticity (also known as functional recovery)
refers to the brain’s ability to replace lost or damaged functions by using existing brain regions in their place
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plasticity
means that the brain is not a static, concrete mass: it is a flexible organ that responds and adapts to environmental stressors
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neuroplasticity example: musician
brain of a professional musician who practises will have a more dense region of grey matter compared to the brain of one who does not
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neural networks
a group of neurons that are interlinked and connected which combine to produce a specific neurological function or process e.g. learning a new language; spatial navigation
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neural pathways
these form when a new behaviour is learned, and these pathways become stronger and more embedded over time and with practise e.g. perfecting a figure-skating move, becoming more fluent in a language
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neural pruning
- refers to the process carried out by the brain in order to increase its efficiency
- synapses and neurons that are no longer used or needed are eliminated by the brain
- a key function of neuroplasticity as it is involved in the pruning of neural networks and neurons that may once have been learned (increased grey matter) but are now no longer used (decreased grey matter)
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study: Maguire (2000) AIM
to investigate how neural networks form as a result of spatial navigation in London black cab taxi drivers
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study: Maguire (2000) METHOD
- 16 healthy, right handed male London black cab taxi drivers who had passed ‘The Knowledge’, a test of spatial navigation, aged 32-62, all taxi drivers for at least 18 months. - Participants were placed in an MRI scanner and their brains were scanned.
- MRI measured the volume of grey matter in the hippocampus of each participant.
- This was compared to pre-existing scans of 50 healthy right handed males (control).
- Grey matter was measured using voxel-based morphometry (VBM), this focuses on the density of grey matter and pixel counting
59
study: Maguire (2000) RESULTS
- posterior hippocampus of the taxi drivers showed a greater volume of grey matter than that of the controls, who had increased grey matter in their anterior hippocampus compared to the taxi drivers.
- Maguire also carried out correlational analysis which showed a positive correlation between volume of posterior hippocampal grey matter and length of time spent as a taxi driver
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study: Maguire (2000) CONCLUSION
the posterior hippocampus may be linked to spatial navigation skills due to a specific neural network of cells within the posterior hippocampus
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study: Maguire (2000) STRENGTHS
- Highly controlled clinical method of obtaining objective data which could then be easily compared and analysed
- The correlational analysis of time spent as a taxi driver linked to increased volume of hippocampal grey matter lends validity to the idea that neural networks form as a result of learning and experience
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study: Maguire (2000) WEAKNESSES
- A correlation can’t show cause-and-effect, so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
- Neural networks may have formed in the participants’ brain due to other, unknown factors
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study: Draganski et al (2004) AIM
to investigate whether structural changes in the brain would occur in response to learning and then cease juggling
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study: Draganski et al (2004) PARTICIPANTS
24 volunteers between the ages of 20 and 24, 21 females and 3 males, all were non-jugglers at the start
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study: Draganski et al (2004) METHOD
- Each participant had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure.
- Participants were allocated to one of two conditions - the jugglers and the non-jugglers. - Juggling condition: were taught a three-ball cascade juggling routine. Were asked to practise this routine and to notify the researchers when they had mastered it.
- At that point, the jugglers had a second MRI scan.
- After the scan, they were told not to juggle anymore and then a third and final scan was carried out three months later.
- The non-juggling group were a control group.
- To analyse the MRI scans, the researchers used voxel-based morphometry [VBM] to determine if there were significant differences in neural density (grey matter) in the brains of jugglers vs. non-jugglers.
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study: Draganski et al (2004) RESULTS
- From the baseline scans they found no significant regional differences in the grey matter between the two conditions
- However, at the end of the first part of the study, the jugglers showed a significantly larger amount of grey matter in the mid-temporal area in both hemispheres - an area associated with visual memory.
- Three months after the participants stopped juggling - when many were no longer able to carry out the routine - the amount of grey matter in these parts of the brain had decreased.
- There was no change throughout the study in the non-juggling sample.
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study: Draganski et al (2004) CONCLUSION
- juggling relies more on visual memory - that is, the perception and spatial anticipation of moving objects - than on “procedural memory” which would more likely show a change in the cerebellum or basal ganglia.
- The study demonstrates how repeated action can lead to the growth of neural networks - and then the cessation of that activity can lead to neural pruning.
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study: Draganski et al (2004) STRENGTHS
- Good internal validity as it took baseline measurements of the participants before the process began so as to ensure that real changes could be observed for comparison
- The findings have a useful application as they can be used to inform possible interventions and therapies to offset degenerative brain conditions e.g. Alzheimer’s
- Used a pretest/posttest design to show differences in neural density over time
- Experimental, helping to argue for a cause-and-effect relationship.
group that didn't juggle and served as a control
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study: Draganski et al (2004) WEAKNESSES
- Self-selecting sample, so it was not representative of a wider population as self-selecting samples often share characteristics e.g. helpful, interested, extrovert
- Participants were not in controlled conditions when they were learning to juggle, so some of them may have over-practised, under-practised or not practised at all which would mean that the neural growth and pruning was due to other factors
- Sample size was very small - so it is possible that by using averages of neural growth, the data may not be reliable
- Field experiment therefore, the study has potential problems with internal validity as the participants were in their home environments for a good part of the study
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neuroplasticity critical thinking
- Neuroplasticity can be observed at multiple scales, from microscopic changes in individual neurons to larger-scale changes such as cortical remapping in response to injury.
- However, when it comes to studying the role of behaviour in the brain, it cannot be observed "live."
- Research is generally correlational in nature; some research is also prospective in nature which allows the researcher to observe change over time; however, these studies are often low in internal validity as it is not possible to control for extraneous variables.
- Animal research tends to be more highly controlled, but this is difficult to generalize to humans.
- Although the physiological processes are the same, there are differences in the level of cognitive complexity between people and animals.
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neurotransmitters
chemicals that are transported via electrical impulses from the presynaptic neuron to the postsynaptic neuron across the synaptic cleft
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neurotransmission
- process where neutrons communicate with other neurons
- occurs when the presynaptic neuron releases neurotransmitters to cross the gap (synapse) between 2 neurones
- neurotransmitter binds to the specific receptor site on the post synaptic neuron, creating an electrical signal called the action potential
- if the receptor site is blocked my another chemical, the post synaptic neuron cannot create an action potential
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inhibitory neurotransmitter
- blocks electrical signals, prevents transmission down cell
- decreases the likelihood that the neuron will fire an action potential by hyper polarising the neuron
- e.g. GABA, glycine, serotonin
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excitatory neurotransmitter
- causes electrical signals to be transmitted down the cell
- increases the likelihood that the neuron will fire an action potential by depolarising the neuron
- e.g. dopamine
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dopamine
- group of neurotransmitters called monoamines
- brain regions associated with dopamine production: ventral tegmental area, nucleus accumbens, caudate nucleus, basal ganglia
- a chemical messenger --> communicates between cells, from brain to the rest of the body
- associated with: reward, motivation, intense pleasure, addiction
- irregular levels are associated with schizophrenia symptoms
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example of how a neurotransmitter binds to excitatory receptor sites
the role of acetylcholine in the formation of spatial memories
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study: Antonova (2011) AIM
investigate if scopolamine affects hippocampal activity in spatial memory formatioN
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study: Antonova (2011) METHOD
- She carried out a double-blind procedure on 20 men.
- Participants were injected with either Scopolamine or a placebo.
- The participants were then put into an fMRI where they were scanned while playing a virtual reality task.
- The goal is for the participants to navigate around an "arena" and reaching a pole.
- After learning where the pole is located, the screen would go blank for 30 seconds, during which they had to rehearse how to get to the pole in the arena.
- When the arena reappeared, the participant was now at a new starting point in the arena and had to use their spatial memory to determine how to get to the location of the pole.
- The participants' brain activity was measured for six trials.
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study: Antonova (2011) RESULTS
- when participants were injected with scopolamine, they demonstrated a significant reduction in the activation of the hippocampus compared to when they received a placebo
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study: Antonova (2011) CONCLUSION + LINK
- appears that acetylcholine could play a key role in the encoding of spatial memories in humans.
- Antonova’s results indicate that in the placebo condition, acetylcholine was binding to excitatory synapses that led to the creation of spatial memories.
- Whereas in the Scopolamine condition, these receptor sites were blocked so acetylcholine could not bind to the site and cause the action potential to fire.
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study: Antonova (2011) STRENGTHS
- The study was a repeated measures design - eliminating the effect of participant variability.
- In addition, the study was counterbalanced- that is, some of the participants did the scopolamine condition first, and others did the placebo condition first, this controlled for practice effect.
- The study was a carried out blindly; this controls for researcher bias.
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study: Antonova (2011) WEAKNESSES
- During the debriefing, several of the participants expressed that they had felt stressed, either as a result of the injection of an unfamiliar drug or being in the fMRI enclosure. This could have an effect on the working of the hippocampus as we know that stress may interfere with memory encoding.
- The sample size was small. The results would need to be replicated in order to decide whether the results are reliable.
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study: Fisher et al (2005) AIM
to investigate a possible link between dopaminergic brain regions/systems and the early stages of romantic love
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study: Fisher et al (2005) METHOD
- He conducted the study on 10 females and 7 males from NY state university.
- All participants reported being ‘in love’ for a mean range of 7 months.
- Participants were placed in an fMRI scanner and shown a photograph of their romantic partner, followed by a distraction task, then a ‘neutral’ photograph of an acquaintance with whom they had no emotional connection.
85
study: Fisher et al (2005) RESULTS
- when the participants viewed the photograph of their loved one, specific areas of their brain were active: the right ventral tegmental areas and the right caudate nucleus.
- Both these areas are strongly associated with dopamine production.
- This has in turn been associated with motivation and reward, meaning that someone has the desire to perform a behaviour because of the positive consequences of that behaviour.
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study: Fisher et al (2005) CONCLUSION
- people in the early, intense stages of romantic love access the areas of the brain most associated with motivation and reward, giving rise to the idea that people may become 'addicted to love’.
- Dopaminergic reward pathways may contribute to the ‘general arousal’ component of romantic love, making it a biological process rather than a cognitive one.
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study: Fisher et al (2005) STRENGTHS
- Findings support previous research into the role of dopamine in substance addiction → interesting to see how romantic love may fall under the same framework of craving and withdrawal
- Use of fMRI clearly shows a link between dopaminergic areas of the brain only when the photo of the romantic partner was shown, increasing internal validity (Fisher really was measuring the effect of romantic love on the brain)
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study: Fisher et al (2005) WEAKNESSES
- Sample with a mean age of 20 are more likely to be socially active and involved with pleasure-focused activities than an older sample, meaning that the ‘pleasure centre’ of their brains would be more receptive to dopamine
- Could be other explanations for the activation of the dopamine-rich areas of the brain being active during the fMRI e.g. excitement of taking part in the study, curiosity to the outcome of the study, Fisher cannot claim cause-and-effect from her findings
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agonist
a molecule that binds to a synaptic receptor and activates it to promote a reaction. E.g. with neurotransmission, this reaction occurs within the synapse
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types of agonists
- exogenous
- endogenous
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exogenous agonist
- drugs that attach to a receptor site for a neurotransmitter and excite the neuron.
- An example of an exogenous agonist is alcohol.
- Alcohol binds with dopamine receptor sites, causing dopamine neurons to fire.
- The firing of these neurons results in the activation of the brain's reward system, the nucleus accumbens.
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endogenous agonist
- any biological chemical that binds to a receptor site.
- This may be a hormone, such as oxytocin, which acts as a neurotransmitter in some cases or a neurotransmitter such as serotonin, dopamine, or acetylcholine.
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agonists may also prevent...
...the inhibition of a neuron , for example physostigmine, which prevents the breakdown of acetylcholine.
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what do agonists do to neurotransmitters
increase their effect
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study: Leyton et al (2013) AIM
to investigate effects of alcohol consumption on the dopamine reward systeM
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study: Leyton et al (2013) METHOD
- He conducted this on 26 healthy social drinkers. He categorised the drinkers based on their risk for alcoholism based on personality traits and having a lower intoxication response to alcohol. This means that they didn't feel as drunk despite having drunk the same amount as other drinkers.
- Each participant underwent a PET scan after drinking either juice and then later, alcohol.
- In each condition, they were asked to drink three drinks in 15 minutes.
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study: Leyton et al (2013) RESULTS
when drinking alcohol, those who were considered "high risk" for alcoholism showed significantly greater activity in the nucleus accumbens
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study: Leyton et al (2013) CONCLUSION
- alcohol is an agonist for dopamine, connecting to dopamine receptor sites and causing the neurons to fire.
- It is theorised that people with a potential for alcoholism have a greater response to the agonist than those at low-risk.
- Furthermore, research shows that those with a low level of dopamine neuron activity due to alcohol consumption often get tired after drinking a small amount of alcohol.
- This is due to the higher levels of dopamine activity counteracting the sedative effects of alcohol.
- By studying the way in which alcohol acts as an agonist on dopamine neurons, it is also possible that researchers could find ways to treat the disorder.
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antagonist
- a molecule that binds to a receptor site on the post synaptic neuron, inhibiting the neuron and decreasing the effect of the neurotransmitter. - This means that a neuron will not fire and as a result a behaviour won’t happen.
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how are antagonists useful to researchers
Researchers are unable to directly observe the role of neurotransmitters, as a result they give human participants or animals an antagonist in order to try and understand the role of neurotransmitters.
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acetylcholine
a neurotransmitter which is involved in memory formation
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drugs as antagonists
If a drug (e.g. ecicopam) decreases the effect of a neurotransmitter (e.g. dopamine) it is known as an antagonist
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study: Rasmusson and Dadar (1979) AIM
- test the antagonist scopolamine and its affect on memory.
- to see what happens when acetylcholine receptors are blocked and the neurons aren’t permitted to fire.
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study: Rasmusson and Dadar (1979) METHOD
- They gave participants a scopolamine tablet and asked them to learn either a series of numbers or solve a maze task.
- There was a second condition in which participants were given a placebo as a control.
- In the number series condition, verbal declarative memory was being tested.
- In the maze task, spatial memory was being tested.
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study: Rasmusson and Dadar (1979) RESULTS
- there was no significant difference between the placebo group and the acetylcholine antagonist group in the number series condition.
- However, participants in the scopolamine group made more errors and took longer to solve the maze.
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study: Rasmusson and Dadar (1979) CONCLUSION + LINK
- acetylcholine may not have a significant role in the encoding of declarative memories.
- Because they were able to use the antagonist and block acetylcholine receptor sites, the researchers were able to improve their understanding of the role of the neurotransmitter acetylcholine in memory formation.
