Biological Approach Flashcards
(30 cards)
Techniques used to study the brain in relation to behavior: Study one technique used to understand the brain and behavior (The relationship between the brain and behavior).
fMRI (functional magnetic resonance imaging:
Functional due to the fact that it is dynamic, captures brain processes over time.
Usually, a subject is instructed to complete a task, and hence areas of the brain are activated and blood flow increases in said areas. A signal is then obtainable from the oxygenated blood, known as the BOLD signal.
The (spatial) resolution is measured in voxels (volumetric pixels), where one voxel contains several million neurons. The ‘FPS’ of the scan is called temporal resolution, and currently lies at about 1 second.
fMRI is strengthened by good spatial resolution and that it allows to see brain processes.
Limited by poor temporal resolution (no fast brain processes) and the fear (random noise), similar to MRI.
(use Fisher, Aron and Brown (2005) as for section on neurotransmitters).
Localization of function: Study one example of localization of function (The relationship between the brain and behavior).
Maguire et al (2000) [see section on neuroplasticity]
Neuroplasticity: Study one example of neuroplasticity (The relationship between the brain and behavior).
Maguire et al (2000):
A: correlational study to investigate the structure of the hippocampus to validate a hypothesis that it is involved in spatial abilities.
M: Training program
P: 16 males, right-handed, good health London taxi drivers with 1.5 years’ experience. Control: 50 right-handed healthy males that weren’t taxi drivers. All participants received MRI scans.
R: the volume of gray matter was similar, but it was redistributed for the taxi drivers. They had more gray matter in the posterior hippocampus compared to the anterior as opposed to non-Taxi drivers.
C: Correlation between variables. The hippocampus has been linked to the way in which humans are able to remember directions and where they have been, known as spatial memory.
E: Quasi-experiment: the allocation of groups was not randomized. Only correlational. Not very generalizable. It does however provide evidence in support of the localization of spatial memory in that it could be linked to the hippocampus.
Neuroplasticity
the ability of the brain to change through synaptic connections between neurons due to environmental and genetic factors.
Neuron
Neurons are nerve cells and the basic building blocks of our entire nervous systems. The neurons act as sensors for all types of stimuli and communicate the stimuli throughout the body – they transfer information throughout the brain, which is communicated through chemical signals.
Neural network
series of connected neurons whereby information travels through chemical signals. They help us form habits.
Naural/synaptic pruning
When we stop practicing something which we have earlier, our synaptic connections (synapses are how information is travelled, located on our dendrites which are little branches on the neurons) slowly dissipate. We lose synaptic connections because we don’t use them: they are pruned.
Use Draganski et al (2004) for question on neural pruning: juggling, brain scans before during and after; neural pruning occurred. Jugglers and non-jugglers.
Neurotransmitters and their effects on behavior: Study one neurotransmitter and its effect on behavior. (The relationship between the brain and behavior).
See Atri et al (2004) in agonists and antagonists.
Agonists and antagonists (The relationship between the brain and behavior).
Atri et al (2004):
A: aimed at investigating the role of acetylcholine in memory formation with particular focus centered around what is known as proactive interference, which is when previously acquired information interferes with the acquisition and retrieval of new information. Focused on how the agonist glycepyrrolate and antagonist scopolamine influences the action potential.
M: independent measures design
P: garnered a sample of 28 participants, this sample was required to read a list of 18 related pairs of closely related words (e.g., robber and jail), after which a 30–50-minute delay ensued and they then read another list of words (here, the second word was changed (i.e., robber and x) after this time had elapsed, finally having to recall the words. A second trial followed the same procedure, but participants were admitted either scopolamine, glycopyrrolate, or no injection. As glycopyrrolate is supposed to enhance the acetylcholine receptor sites, it was expected that this agonist would lead to more words being remembered.
R: results showed that, although most conditions lead to a similar mean of words recalled, there was a significant difference between the words recalled for the glycopyrrolate agonist and the participants who were admitted scopolamine.
C: this study therefore proves the role of the agonist glycopyrrolate in its role in enhancing the acetylcholine neurotransmitter and its receptor sites, demonstrating how agonists can operate and effect a given physiological outcome by enhancing the receptor sites of a neurotransmitters.
E: participant differences, since it was not a repeated measures design.
Synapse
Located where the axon of one neuron approaches a dendrite or soma (cell body) of another neuron. The connections between neurons. Each neuron, on average, has about 15000 synapses with other neurons. They form synaptic connections, whereby information travels.
Excitatory and inhibitory neurotransmitters
Chemical messenger (about 100 of them). They are constantly synthesized in the neutron and moved to the axon terminal to be stored. A released neurotransmitter is available in the synapse for a short period during which it may be metabolized, pulled back through reuptake or reach the post-synaptic membrane (dendrite) and bind to one of the receptors on its surface. Neurotransmitters transmit through the synaptic cleft. Neurotransmitters are either excitatory or inhibitory (excitatory or inhibitory effects on the neuron, meaning they either increase or decrease the likelihood of action potential).
Agonist
Chemicals that enhance the action potential of a neurotransmitter
Antagonist
Chemicals that counteract a neurotransmitter and so prevent a signal from being passed further.
Hormones and their effects on behavior: study one hormone and its effect on behavior (Hormones and pheromones and their effects on behavior)
Hormones: chemical messengers released from endocrine glands that travel through the blood system to influence the nervous system to regulate behaviors such as aggression, mating, and parenting of individuals.
De Dreu et al (2011)
A: Studied whether oxytocin promotes human ethnocentrism, a type of intergroup bias where one’s own ethnic group is perceived as more important than or superior to others.
M: repeated measures design. Used trolley problem.
P: sampled indigenous Dutch male participants. Participants then self-administered oxytocin or a placebo nasally. Afterwards, participants were shown images of people belonging to their in-group (Dutch males) or an outgroup (Middle Easterners/Germans). Finally, used moral choice dilemma tasks such as the trolley dilemma.
R: under oxytocin males were more likely to sacrifice an outgroup target than an ingroup target, while under the placebo there was no difference.
C: This suggests that oxytocin promotes ingroup favoritism.
E: Correlational. Oxytocin has not usually been associated with this behavior.
Pheromones and their effects on behavior: Study one pheromone and its effect on behavior. (Hormones and pheromones and their effects on behavior)
Pheromones: Chemical substances responsible for chemical communication – they carry stimulation and affect behavior.
Hare et al (2017):
A: Aimed at investigating whether androstadienone (AND) and estratetraenol (EST) signal gender and affect male perception.
M: Repeated measure design
P: heterosexual participants completed two computer-based tasks twice on two consecutive days. While completing the task, they were exposed to either AND or EST, or just the control scent. The participants were then to look at five gender-neutral facial morphs. In the second task, participants were shown opposite-sex photographs and asked to rate the attractiveness (1-10).
R: Results showed no impact of AND and EST on the rating of attractiveness.
C: AND and EST are not sex pheromones.
E: confounding variables, more smells.
Genes and their effects on behavior: study one gene and its link to behavior. (The relationship between genetics and behavior.)
Kaminsky et al (2008)
A: investigated the role of epigenetics in phenotypical differences between MZ twins
M: case study and questionnaires
P: looked at two 49-year-old females, one a war journalist and the other an office manager in a law firm. Personality questionnaires were carried out and showed differences; the law twin had a tendency to overreact to minor problems and is more risk-aversive than war twin.
R: Researchers found one gene, the DLX1 gene (responsible for formation of neurons creating a stress center of the brain) to have an effect.
C: concluded that DLX1 methylation may play a role in the development of stress responses in MZ twins.
E: a bit inconclusive: “may”
Genetic similarity: Study genetic similarity (twins, siblings, parents, adopted children) for one behavior. (The relationship between genetics and behavior.)
The transracial adoption study (Minnesota adoption study) (reported by Scarr and Weinberg, 1983):
A: Investigate if black children adopted by white families performed on IQ tests and school achievement as well as other adoptees.
M: Adoption study, longitudinal, correlational.
P: Sampled 101 adoptive families who have biological children and adopted a transracial child. Some of the adopted children were black and others white. The children were adopted around age 0-2. The children were assessed on IQ and school achievement tests.
R: Showed an increase in IQ scores in black children in white families, and that early adoption resulted in higher IQ scores than late adoption.
However, the correlation between the IQ of adoptive parents and adopted children was lower than the correlation between adopted children and their biological parents, which suggests an influence of genetics as well.
C: Adoption increased cognitive abilities – and an increase in IQ occurs due to environmental factors, but the child’s genetics have a say in how the child responds to the environmental factors.
Also, young, adopted siblings had an IQ correlation nearly as high as biological siblings, which contradicts the other findings of genetic factors on cognitive ability (biological parents having correlating IQ to biological child).
E: Ethical considerations?
Twin studies
studying dissimilarities between identical twins (monozygotic or MZ) or fraternal (dizygotic) twins.
Kinship studies
studies focusing on patterns of social relationships in cultures.
Evolutionary explanation for behavior: Study one example of an evolutionary explanation for behavior.
Curtis, Aunger and Rabie (2004):
A: suggested that disgust evolved as protection from the risk of disease.
M: survey/questionnaire
P: Researchers reasoned that if this was true, the following condition would have to be fulfilled:
- disgust should be felt more strongly when faced with a disease-salient stimulus
- disgust should operate in a similar way across cultures
- disgust should be more pronounced in females (have to protect babies)
- disgust should become weaker as the individuals age (don’t have to protect babies anymore)
- disgust should be stronger in contact with strangers.
Researchers made a survey with questions where participants had to (answer where they were from, age, gender, etc.) rate how disgusting certain images were.
R: All five conditions were fulfilled.
C: Study supports the evolutionary explanation of disgust as a response that reduces the risk of disease.
E: Merely a theory.
Gene expression
the process by which the heritable information in a gene, the sequence of DNA base pairs, is made into a functional gene product, such as protein or RNA. The basic idea is that DNA is transcribed into RNA [ribonucleic acid] (transcription), which is then translated into proteins (translation). There are many mechanisms that can be used by the body to increase or decrease the production of proteins based on the genetic code. These mechanisms are known as regulation of gene expression, and this results in epigenetic changes (deviation in phenotype from the genetic code in DNA) (https://cdn.britannica.com/96/114896-050-3F22219B/Genes-promoter-regions-production-introns-exons-gene.jpg)
Methylation
DNA methylation effects the expression of a gene. It occurs by the addition of a methyl group to the DNA, modifying the function of genes.
Epigenetics
the phenomenon of what role genetics take in the shaping of behavior as an organism matures due to biological factors and environmental inputs. This mainly concerns how nurture can have an impact on physiology and behavior. Epigenetic changes are reversible.
Animal models (HL extension: animal research)
a concept that refers to using animal research to test a certain cause-effect hypothesis about a certain human behavior. An example would be stress models (explain depression due to exposure to stressful situations), separation models (separation from others causing depression), medical models (chemical imbalances in the brain), etc.
Ethical considerations that can be applied:
- Anesthesia and euthanasia for more humane treatment.
- Guidelines and healthy benevolent treatment for nonhuman animals.
- Non-invasive methodologies and experimental techniques. E.g. behavioral observation
Main experimental manipulation types used in animal models:
- Genetic manipulation (when animals are bred in a certain way)
- Invasive manipulations with the nervous system (brain parts are stimulated with electrodes, lesioned, or removed)
- Invasive manipulations with other body parts (by substances or damage)
- Behavioral and environmental manipulations (e.g. electric shocks for maze training of rats)
