Brain and Behaviour Flashcards
Imaging techniques
MRI and fMRI
MRI
Magnetic Resonance Imaging :
Gives 3d picture of brain structures. Uses magnetic field and radio waves to map activity of hydrogen molecules, which are present in different brain tissue to different degree(S).
Advantages of MRI
- Non invasive procedure (minimal harm)
- high resolution image
Disadvantages of MRI
- only indicates structure, not actually mapping what’s happening in the brain
- research is correlational in nature, not allowing a clear cause and effect relationship
fMRI
Functional Magnetic Resonance Imaging :
Shows actual brain activity and indicates which areas of the brain are active when engaged in a behaviour/cognitive process. Measures changes in blood flow in active brain.
fMRI advantages
- higher resolution than PET scans + easier to carry out
- non invasive
Maguire (2000)
Aim: To examine whether structural changes could be detected in the brain of people with extensive experience of spatial navigation.
Participants: 16 right-handed male London taxi drivers , 50 right-handed males who did not drive taxis (control)
- Had to complete the “Knowledge” test and have license for at least 1.5 years
- range of ages (not a confounding variable)
Method:
- Correlational (IV is not manipulated)
- Quasi-experiment
- Single-blind (researcher didn’t know whose brain they were looking at)
Procedure:
1) The brain of each participant underwent MRI scans
2) Scans were compared to the control group
3) Data was measured using two different techniques : Voxel-based morphometry (USED TO QUANTIFY THE DENSITY OF GREY MATTER IN BRAIN) and pixel counting (USED TO COUNT PIXELS IN PICTURES PRODUCED BY MRI SCANS)
Results:
- Pixel counting revealed that the posterior hippocampi (taxi driver) was bigger and anterior hippocampi were smaller
- VBM showed that vol. of right posterior hippocampi correlated with the amount of time spent as a taxi driver
- Other regions of the brain did not show any changes
Conclusion:
- Demonstrates the the hippocampus may change in response to environmental demands (with the help of MRI technology)
Evaluation of Maguire (2000)
Strengths:
- Quasi : ensured researchers were unable to manipulate IV
- Single blind : avoided researcher bias
- No ethical implications (MRI is non-evasive)
Limitations
- Low generalisability (all male)
Sharot et al (2007)
Aim: To determine the role of biological factors on flashbulb memories
Participants:
- 24 people who were in NYC on day of 9/11 attack
- Provided informed consent
Method:
- Quasi experiment (conducted 3 years after attack)
Procedure:
1) Participants were put into an fMRI
2) While in the scanner they were presented with word cues on a screen
3) The word cues were projected along the word “Summer” or “September” (to have participant link the word with summer holidays/9-11)
4) Their brain activity was observed (personal memories of summer served as baseline of brain activity when evaluating nature of 9/11 memories)
5) Participants were asked to rate their memories for vividness, detail, confidence in accuracy and arousal
6) They were asked to write a description of their personal memories
Results:
- only half reported having “flashbulb memories”
- activation of amygdala for participants who were downtown was higher when recalling 9/11 than summer memories
- participants who were further away had equal levels of response in the amygdala when recalling both events
- strength of amygdala activation at retrieval was shown to correlate with flashbulb memories
Conclusion:
- suggest that close personal experience may be critical in engaging the neural mechanisms that produce the vivid memories characteristic of flashbulb memory.
Sharot et al evaluation
Strengths:
- No ethical implications
Limitations:
- fMRI : artificial -> low ecological validity
- small, culturally biassed sample size -> low generalisability
Flashbulb memories
Occurs when certain memories are stronger than others due to their emotional nature
fMRI vs MRI
fMRI :
- modified version of MRI scanner
- captures brain activity
- revolutionised brain mapping (enabling researchers to evaluate brain/spinal cord without invasive procedures or drug injections)
- provides greater insight into how chemical messengers (neurotransmitters and hormones) impact brain activity and behaviour -> could help understand the origins of behaviours such as violence and PTSD
MRI
- spots problems that conventional imaging techniques might miss
What is localisation of function
The theory that specific parts of the brain are responsible for specific behaviours or cognitive processes. Specific areas of the brain are responsible for certain tasks, such as language processing, vision, motor control, or memory.
Localisation of function and neuroimaging techniques
Advances in neuroimaging techniques such as (fMRI) and (MRI) have allowed researchers to further investigate the localization of function in the brain
HM: Milner (1966)
Aim: Investigates the role of the hippocampus on memory formation
Participants:
- 1 participant (HM)
- hit by a cyclist at a young age (sustained a head injury)
- due to debilitating seizures, experimental surgery (remove tissue from medial temporal lobe (including hippocampus) on both sides of the brain
Method:
- Method triangulations (utilising different strategies to carry out research)
- Longitudinal case study
Procedure:
1) Psychometric testing, in which HM was given IQ testing and had above average results
2) Direct observation of his behaviour
3) Interviews with both HM and and with his family members
4) Cognitive testing, where HM had to take part in memory recall tests and learning tasks.
5) An MRI was conducted after all the tests to determine the extent of the damage done to HM’s brain
Results:
-HM could not acquire new episodic knowledge (memory for events) and he could not acquire new semantic knowledge (general knowledge about the world).
- Capacity for working memory
- able to carry on a normal conversation (minimal retention)
Conclusion:
The issue with converting short-term memories to long-term memories can be linked to damage to the hippocampus because this is the region where the neurotransmitter acetylcholine is thought to play a key role in memory formation and learning.
Evaluation of HM: Milner
Strengths:
- High ecological validity ( no variables were manipulated + HM was observed in natural environment )
- No ethical implications (consent was given)
- longitudinal: lasted over 50 years (changes could be observed over time
Limitations:
- Not easily replicable
- Retrospective in nature : don’t know a lot about HM’s cognitive abilities before the accident
What is neuroplasticity
It refers to the brain’s ability to reorganise and adapt by forming new neural connections and pathways.
The brain’s ability to change in response to internal and external stimuli (fundamental process that underlies learning, memory, and recovery from injury.
Neuroplasticity (technical)
Neurons link together to form a new trace in the brain each time we learn something new. This is called dendritic branching because the dendrites of the neurons expand in numbers and link with other neurons.
Dragonski (2004)
Aim: Investigate whether learning a new skill would have an effect on the brains of the participants
Participants:
- 24 volunteers (20-24 yrs)
- all non-jugglers
Method:
- FIELD experiment
Procedure:
1) Each participant had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure
2) Two conditions: jugglers and non-jugglers
- Jugglers were taught a juggling routine. They were instructed to rehearse the routine and to let the researchers know when they were successful
3) The jugglers then underwent a second MRI scan. After the scan, they were instructed to stop juggling, and three months later, a third and final scan was performed
4) Non-juggling group was used as a control group
5) Researchers compared the neural density (grey matter) in the brains of the two conditions using [VBM] to analyse the MRI images
Results:
- No substantial regional variations in grey matter
- @ first stage : mid-temporal region (connected to memory) had more grey matter in jugglers’ brain
- Diminished after three months, many were no longer able to do routine
Conclusion:
Suggested that juggling relies more on visual memory (the perception and special anticipation of moving objects) than on procedural memory which would more likely show a change in the cerebellum or basal ganglia.
Evaluation of Dragonski (2004)
Strengths:
- control group
- replicable
Limitations:
- internal validity? : field experiment (home environments most of the time)
Studies for brain techniques
Maguire (2000) and Sharot et al (2007)
Studies for Localisation
Maguire (2000) and HM: Milner (1966)
Rosenzweig et al (1972)
Aim: Investigate whether environmental factors could affect the development of neurons in the cerebral cortex
Participants:
- Rats
Procedure:
1) Rats were divided into three groups at random
- IC: Impoverished condition (no toys and maze) (confined to separate cages)
- CC: Control condition (cage)
- EC: Enriched condition (10-12 rats were housed in a cage with various stimulation items for them to explore and play with)
2) Free and sufficient food and drink for all conditions
3) Rats would spend 30-60 days in their respective environments before they were killed in order for the changes in their brain’s anatomy to be studied.
Results:
- EC and IC had differences
- Cortex of EC was thicker and heavier
- EC rats had more activity in the cerebral cortex neurons involved in acetylcholine transmission (crucial neurotransmitter for memory and learning)
Conclusion:
The thickness of the cortex and the overall weight of the brain can increase when being in an enriched environment
Evaluation of Rosenzweig et al (1972)
Strengths:
- Highly controlled laboratory experiment (easier to establish cause-effect relationship)
- Results have been replicated many times, indicating data is reliable
Limitations:
- Difficult to generalise results to humans unless research with humans provides same results
- Ethical concern : unjustified stress/harm
*should undergo cost-benefit analysis in order to see whether goals of the study are worth harm done to animals
Studies of neuroplasticity
Rosenzweig et al (1972) and Dragonski (2004) and Maguire (2000) [SAQ]
Neurotransmission
Neurons
- one of the building blocks of behaviour
- send electrochemical signals to the brain so that one can respond to stimuli
- the process by which these signals are sent is called neurotransmission.
Drugs and neurotransmission
Influence the synapse in two ways: act as agonists/antagonists
Antagonists bind to synaptic receptors but they decrease the effect of the neurotransmitter.
What are neurotransmitters
The body’s natural chemical messengers that transmit information from one neuron to another.
Shown to have a range of different effects on human behaviour such as mood, sleep, and learning and memory.
Roger and Kesner (2003)
Aim: To determine the role of acetylcholine in memory formation. Acetylcholine is an antagonistic neurotransmitter.
Participants:
- 30 rats
Procedure:
1) Familiarised the 30 rats with a Hebb Williams maze -> placing food in one of the corners.
2) Randomly assigned to one of two conditions: injected with scopolamine or with a saline solution 10 minutes before running the maze.
3) Scopolamine blocks the acetylcholine receptor sites and thus inhibits any response. The saline solution was a placebo injection.
4) Placebo inject -> ensure that getting an injection alone was not responsible for a change in memory. They were made directly into the hippocampus (major role in learning and memory)
5) Encoding of memory was assessed by the average number of errors made on the first five trials of Day 1 compared to the last five trials of Day 1
6) Average number of errors made on the first five trials of Day 2 compared to the last five trials of Day 1 -> assessed retrieval.
Results:
- Scopolamine group took longer + made more mistakes in learning the maze.
- But it didn’t seem to have an effect on the retrieval of memories that had already been created
Conclusion:
Acetylcholine might play a critical role in the consolidation of memory.
Evaluation Roger and Kesner (2003)
Strengths:
- Highly controlled lab experiment avec placebo effect -> avoids effect of extraneous variables -> uphold integrity of data
Limitations:
- Difficult to generalise results from animal studies to humans because the results may not be wholly applicable
- Ethical concern
*could lead to the development of treatments for people suffering from dementia or Alzheimer’s disease as they both are memory disorders (assuming that acetylcholine plays a role in memory formation).
Antonova et al (2011)
Aim: Investigate whether or not scopolamine affected hippocampal activity in the creation of spatial memory
Participants: 20 healthy males (average age 28)
Method:
- Repeated measures
- Double blind
Procedure:
1) Participants were assigned to one of two conditions at random (scopolamine or placebo injection, 70-90 minutes before participating in the experiment)
2) Scopolamine is an antagonist which blocks acetylcholine receptor sites. This decreases the availability of acetylcholine which assists in encoding memories and learning.
4) The “Arena task” was played by the participants as they were scanned in an fMRI, they were being tested on their capacity to form spatial memory.
5) Before playing the game, the players had training to ensure that they could handle the joystick easily and knew its rules. They participated in the experiment after receiving training.
6) They had to make it through the arena to reach a role, screen would go dark for 30 sec when they reached. They had to practice getting to pole. They were in a different staring position every time.
7) For six trials, the individuals’ brain activity was monitored. The participants returned between 3 - 4 weeks later and redid the test, receiving the opposite treatment to the original study.
Results:
- Scopolamine injections: showed less hippocampal activity
Conclusion:
Acetylcholine could be essential for the human brain’s encoding of spatial memories.
Evaluation of Antonova et al (2011)
Strengths:
- Repeated measures: eliminated effect of participant variability
- double blind : avoids researcher bias
Limitations:
- sample size: limiting generalisability
- laboratory experiment: may have affected the stress of the participants which in turn may have affected the brain image results
Studies for neurotransmission
Roger and Kesner (2003), Antonova et al (2011)
