bioSL Flashcards
(10 cards)
Techniques to study the brain
MRI:
- magnetic resonance imaging
- gives 3D image of brain structures
- uses magnetic fields and radio waves to map the activity of hydrogen molecules in different areas of the brain
- non-invasive
- high resolution
- doesn’t map activity, only structures
FOCUS ON THE TECHNIQUE NOT THE STUDY
Study:
Dranganski et al (the jugglers) - experiment
- 24 volunteers
- all recieved a scan at the beginning
- group A: asked to learn a juggling routine
- group B: control
- second scan after they mastered the routine
- asked to stop practicing
- last scan after 3 months
- results: more gray matter in the mid-temporal area after juggling, decreased after they stopped juggling, no change in control
LOCALISATION
Theory:
- the theory that specific areas of the brain are responsible for specific functions and cognitive processes
- the brain works more as an integrated system, and it is rare that an individual area carries out a process in isolation from the rest of the brain
- mid-temporal area - associated with visual memory
Study:
Dranganski et al (the jugglers) - experiment
- 24 volunteers
- all recieved a scan at the beginning
- group A: asked to learn a juggling routine
- group B: control
- second scan after they mastered the routine
- asked to stop practicing
- last scan after 3 months
- results: more gray matter in the mid-temporal area after juggling, decreased after they stopped juggling, no change in control
- conclusions: suggests that juggling relies more on visual memory (perception and anticipation of moving objects) rather than procedural memory (e.g. cerebellum)
NEUROPLASTICITY
Theory:
- definition: the brain’s ability to alter itself to adapt to changes in the body and the environment
- creating and breaking of neural connections in the brain as a result of stimulation or the lack of it
- dendritic branching - creating new neural pathways
- long-term potentiation - when the action is repeated, the synapses become stronger
- definition: removal of synapses that are no longer needed
makes the functioning networks more efficient
- synaptic pruning
Study:
Dranganski et al (the jugglers) - experiment
- 24 volunteers
- all recieved a scan at the beginning
- group A: asked to learn a juggling routine
- group B: control
- second scan after they mastered the routine
- asked to stop practicing
- last scan after 3 months
- results: more gray matter in the mid-temporal area after juggling, decreased after they stopped juggling, no change in control
- conclusions: learning new skills creates new neural connections, unused pathways are broken (neural pruning) to increase efficiency of more frequently used ones
NEUROTRANSMISSION
Theory:
- neurotransmission is the process by which electrical impulses travel along the nerve cells to pass a message around
- electrical impulse = action potential
- when the action potential travels down the axon, the neuron releases neurotransmitters into the synapse, the neurotransmitters travel across the synapse and bind to the receptor sites on the postsynaptic membrane
- neurotransmitter: chemical that transmits information from one neuron to another
Agonist - acetylcholine
activates the receptor
effect on spatial memory
Antagonist - scopolamine (inhibits acetylcholine)
binds to the receptors without activating them and therefore decreases the receptor’s ability to be activated by other agonists - no action potential sent down the neuron
Study:
Antonova et al - experiment
- 20 males
- scopolamine or placebo - double-blind
- fMRI used to monitor brain activity
- they played a VR game that was used to assess their ability to create spacial memories (navigating around the arena towards a pole, when they reach a pole the view goes blank for 30s and then they’re back in the arena at a different point and they have to use spatial memory to get to the pole again)
- repeated measures (after 3/4 weeks)
- results: placebo - more activation in the hippocampus, better at encoding and retrieving spatial memories
- conclusion: scopolamine has a negative effect on spacial memory
HORMONES
Theory
- hormones - testosterone
form of chemical communication within the body, released by glands
- they reach target cells or organs by bloodstream and they take longer to take action than neurotransmitters but the effects are also more long-lasting
- testosterone is sometimes associated with aggressive behaviour
Study:
Carre et al - experiment
- level of aggression and dominance assessed beforehand
- 121 males
- testosterone injection or placebo - double-blind
- only the men who had already been assessed as aggressive responded aggressively
- conclusion: testosterone alone does not lead to aggression, it has a facilitative role
PHEROMONES
Theory:
- chemical communication between members of the same species
- can affect the behaviour of other individuals
- there is no conclusive evidence about the effect of pheromones on humans, no human pheromone has been found so far
Study:
Wedekind et al - experiment
- 49 female, 44 male
- men asked to wear a t-shirt to sleep for 2 nights (kept in a plastic bag for the day, no spicy foods, strong perfume, scented cosmetics, smoking, sex, alcohol etc)
- each woman asked to smell 7 t-shirts through a hole in a cardboard box and rate them based on intensity and attractiveness (3 similar MHC, 3 different, 1 unworn control)
- results: different MHC = more pleasant BUT the opposite for women on birth control
KINSHIP STUDIES
Theory:
- When the risk of developing a disorder increases within a family, this indicates a potential genetic root of the behavior.
- Today, kinship studies are more frequently part of larger linkage or association studies.
- They measure the frequency of a behavior across generations.
- They measure the frequency of a behavior within a generation.
- They use case-control studies (retrospective). They clearly define two groups at the start (case and control) They look back to assess whether there is a statistically significant difference in the rates of exposure to a defined risk factor between the groups - in this case, to potential genetic inheritance.
Study:
Nestadt et al - correlational study
- 80 people with OCD, 73 control cases, and their first-degree relatives
- semi-structured interviews with the relatives (blindly)
- people with OCD relatives had more obsessions and compulsions (12 vs 3%)
GENETICS
Theory:
- gene-environment interaction - the gene alone does not cause a behaviour (epigenetics)
- epigenetics - for a behaviour to occur, the gene has to be expressed, not only present
Study:
Caspi et al - correlational study
- examined the role of the 5-HTT gene in depression (gene associated with serotonin pathways)
- group A: 2 short 5-HTT allele
- group B: 1 short 1 long
- group C: 2 long
- “Stressful life events” questionnaire about the frequency of 14 events + assessed for depression
- short + stressful life events - more depression BUT the gene alone did not lead to depression
EVOLUTIONARY
Theory:
- individuals that better adapt to the environment have a better chance of survival and reproduction (natural selection)
- Darwin
- Evolutionary psychologists attempt to explain how certain human behaviors are the result of the development of our species over time.
- assumptions that behaviours are genetic
Study:
Wedekind et al - experiment
- 49 female, 44 male
- men asked to wear a t-shirt to sleep for 2 nights (kept in a plastic bag for the day, no spicy foods, strong perfume, scented cosmetics, smoking, sex, alcohol etc)
- each woman asked to smell 7 t-shirts through a hole in a cardboard box and rate them based on intensity and attractiveness (3 similar MHC, 3 different, 1 unworn control)
- results: different MHC = more pleasant BUT the opposite for women on birth control
- conclusion: evolutionary explanation for choosing a partner - different MHC = better immunity
ETHICAL CONSIDERATIONS
- consent forms
- debreifing
- right to withdraw
- the men were anonymous
Study:
Wedekind
