Biological SAQs PDF

Biological approach SAQ’s Techniques used to study the brain: fMRI: Unlike the MRI which shows the structure of the brain, the fMRI (Functional Magnetic Resonance Imaging) indicates activity in the brain so it can show brain processes. During the scan participants are usually asked to carry out a...

Biological approach SAQ’s Techniques used to study the brain: fMRI: Unlike the MRI which shows the structure of the brain, the fMRI (Functional Magnetic Resonance Imaging) indicates activity in the brain so it can show brain processes. During the scan participants are usually asked to carry out a task so their brain activity can be recorded. The fMRI scanner measures changes in blood flow in the active brain and a computer turns the images into a 3D coloured moving image of brain activity. Specifically, the method uses the BOLD (blood oxygen level dependent) signal. When a brain region is active during the performance of a task, the organism supplies it with oxygenated blood. When oxygenated blood is placed in an external magnetic field, it emits pulses of energy, but the response depends on the blood flow and level of oxygenation. Since we know that the most active brain areas are supplied with the most blood, this also allows us to see which brain areas are most active during the performance of a particular task. Study used: Sharot et al Aim: To determine the role of neural mechanisms on flashbulb memories. Method: (QUASI EXPERIMENT) The sample was made up of 24 participants who were in New York City on that day. Participants were put into a fMRI. While in the scanner, they were presented with word cues on a screen. The list of words is presented in the table below. In addition, the word "Summer" or "September" was projected along with this word in order to have the participant link the word to either summer holidays or to the events of 9/11. Participants' brain activity was observed while they recalled the event. The memories of personal events from the summer served as a baseline of brain activity for evaluating the nature of 9/11 memories. Findings: · Selective activation of the left amygdala occurred when participants were recalling events from 9/11, but not control events. · The rates of this selective activation were different in the two groups: it was observed in 83% of participants from the Downtown group and 40% of participants from the Midtown group. · During the 9/11 trials the Downtown group showed higher amygdala activation than the Midtown group, but there was no difference across the groups for summer trials. · Selective activation of the left amygdala correlated with the proximity of the participant to the World Trade Center during the attacks. · The strength of amygdala activation at retrieval was shown to correlate with flashbulb memories (a greater sense of detail and a strong confidence in the accuracy of the memory). Conclusion: The selective activation of the left amygdala may be the neural mechanism of flashbulb memories. The pattern of results confirms that activation is higher when the participant was closer to the attack, so the event was more personally consequential. Also, this pattern was specific to the surprising/shocking memories of 9/11 and not the summer memories. These results suggest that close personal experience may be critical in engaging the neural mechanisms that produce the vivid memories characteristic of flashbulb memory. Localisation of function: This is the theory that certain areas of the brain are related to specific functions.Therefore, specific areas of the brain carry out specific functions of the brain.Behaviours, emotions and thoughts start/come from specific parts of the brain.Therefore, damage or alteration to a specific part can cause loss or alteration to a specific functions. Strict localization- is the idea that there is a clear correspondence between psychological functions and brain areas and that all functions can be clearly mapped onto the brain. Weak localization is the idea that one brain area may be responsible for a function, but not exclusively and other areas may take over the function. It also suggests that several brain areas may be responsible for the same function. Some higher order functions are not localized and are widely distributed. Study to use: Sharot et al Aim: To determine the role of neural mechanisms on flashbulb memories. Method: (QUASI EXPERIMENT) The sample was made up of 24 participants who were in New York City on that day. Participants were put into a fMRI. While in the scanner, they were presented with word cues on a screen. The list of words is presented in the table below. In addition, the word "Summer" or "September" was projected along with this word in order to have the participant link the word to either summer holidays or to the events of 9/11. Participants' brain activity was observed while they recalled the event. The memories of personal events from the summer served as a baseline of brain activity for evaluating the nature of 9/11 memories. Findings: · Selective activation of the left amygdala occurred when participants were recalling events from 9/11, but not control events.· The rates of this selective activation were different in the two groups: it was observed in 83% of participants from the Downtown group and 40% of participants from the Midtown group.· During the 9/11 trials the Downtown group showed higher amygdala activation than the Midtown group, but there was no difference across the groups for summer trials.· Selective activation of the left amygdala correlated with the proximity of the participant to the World Trade Center during the attacks.· The strength of amygdala activation at retrieval was shown to correlate with flashbulb memories (a greater sense of detail and a strong confidence in the accuracy of the memory). Conclusion: The results of Sharot et al.'s study demonstrate localization of function by showing that the left amygdala is specifically involved in the processing and vivid recall of emotionally significant memories, such as flashbulb memories. Participants who were closer to the World Trade Center on 9/11 had higher activation in their left amygdala when recalling the event compared to summer memories, while those farther away showed no such difference. This indicates that the left amygdala's role is localized to the encoding and retrieval of emotionally intense and vivid experiences, further supporting the idea that specific brain regions are responsible for distinct cognitive and emotional functions. Neuroplasticity: Neuroplasticity is the ability of the brain to change itself in response to environmental demands. The brain is able to change through the making and breaking of synaptic connections between neurons. Every time we learn something new, the neurons connect via synapses to create a new trace in the brain. The repeated firing of a neuron strengthens the connection; this is called Long Term Potentiation (LTP). When synaptic connections are no longer used, they are eliminated. Modern researchers argue that the brain is constantly changing as a result of experience throughout the lifespan. Neural network & pruning: High levels of stimulation and numerous learning opportunities lead to an increase in the density of neural connections. The repeated firing of a neuron strengthens the connection; this is called Long Term Potentiation (LTP). LTP leads to dendritic branching which is when the dendrites of the neurons grow in number and connect with other neurons, increasing the number of synapses.These connections build up to form neural networks which are connections between neurons that are involved with each other. Neural pruning, also called synaptic pruning is the process whereby unused synapses fade away while the relationship between the synapses of neurons that communicate frequently with each other strengthens, thus increasing functionality. Study to use: draganski Aim: The aim of the study was to see whether learning a new skill - in this case, juggling - would affect the brains of participants. Method: - 24 participants (21 females, 3 males), aged 20-24, volunteered for the study. - All participants were non-jugglers at the start of the study. - Each participant underwent an MRI scan at the beginning of the study. - Participants were randomly allocated to one of two conditions: juggling and non- juggling. - The juggling group was taught a three-ball cascade juggling routine and asked to practice until they mastered it. - Once the juggling routine was mastered, the juggling group had a second MRI scan. - After the second scan, participants in the juggling group were instructed to stop juggling. - A third MRI scan was conducted three months later after the juggling group stopped practicing. - The non-juggling group served as the control throughout the study. Findings: - Researchers used voxel-based morphometry (VBM) to analyze MRI scans for differences in neural density (grey matter) between jugglers and non- jugglers. - Baseline scans showed no significant differences in grey matter between the two groups before the study began. - At the end of the first part of the study, jugglers showed significantly more grey matter in the mid-temporal area in both hemispheres, associated with visual memory. - Three months after stopping juggling, when many jugglers could no longer perform the routine, grey matter in these areas decreased. - The non-juggling group showed no changes in grey matter throughout the study. - Juggling appeared to rely more on visual memory (perception and spatial anticipation of moving objects) than on procedural memory, which would typically affect the cerebellum or basal ganglia. Conclusion: - The study demonstrates the relationship between brain and behavior by showing how learning a new skill affects brain structure. - Jugglers showed an increase in grey matter in the mid-temporal area, associated with visual memory, after learning the juggling routine. - The changes in brain structure were specific to the skill being learned, indicating adaptation to the visual-spatial demands of juggling. - The decrease in grey matter three months after stopping juggling suggests that these brain changes are not permanent and require continued practice to be sustained. - The findings highlight the role of visual memory in juggling, as opposed to procedural memory, which would more likely affect areas like the cerebellum or basal ganglia. - This study supports the concept of brain plasticity, showing how behavior (skill learning) can influence neural structure and function. Neurotransmitters: "Information" travels through the neural networks by stimulating the dendrites of a neuron. The neuron initiates an electrical impulse towards the terminal buttons. The terminal buttons then release chemical neurotransmitters across the synapse or synaptic gap. These neurotransmitters attach to the dendrites of another neuron and have an effect on behaviour. After the neurotransmitter has crossed the synapse, it fits into receptor sites on the post-synaptic membrane, like a key in a lock. Once the message is passed on, the neurotransmitters are either broken down by enzymes or reabsorbed through reuptake channels in the pre-synaptic membrane. Agonists and antagonists: An agonist is any molecule that can bind to and activate a receptor site on a post-synaptic neuron, to induce a biological reaction. All neurotransmitters are agonists for receptor sites. They are referred to as endogenous agonists since they are biologically already part of our nervous system. So, acetylcholine is an agonist for ACh receptor sites. An antagonist is any chemical that inhibits the action of a neurotransmitter. Antagonists are drugs that block the receptor site on the post synaptic membrane and do not allow the neurotransmitter to do its job, so no action potential is sent down the neuron. Scopolamine is an antagonist for ACh receptor sites. Neurotransmitter I am doing: Often the study of neurotransmitters is done indirectly, often by using an antagonist which blocks the receptor site of a neuron and prevents it from performing its job. In the study by Antonova the neurotransmitter scopolamine blocks the action of acetylcholine which plays a role in learning and memory. Study to use: Antonova et al Aim: To investigate whether scopolamine affected hippocampal activity in the creation of spatial memory in humans Method: Participants are 20 healthy male adults, with a mean age of 28 randomly allocated to be injected with either Scopolamine or a placebo 70 ~ 90 mins before experimental task. Then placed into a fMRI while playing the "Arena task", a VR game where the goal is to reach a pole in an "arena". Participants are trained to the point of understanding the rules of game and familiarize with control before the start of the experiment, then their brain activity is measured for 6 trials. 3 ~ 4 weeks later, participants redid the test with opposite treatment. Findings: Participants who received scopolamine performed worse on the memory task than those who received the placebo. Additionally, fMRI scans showed that scopolamine reduced activity in the hippocampus, a brain region critical for spatial memory and known to be modulated by acetylcholine. Conclusion: Acetylcholine plays a significant role in the encoding of spatial memories as shown by the results (inhibiting acetylcholine leads to a decrease in spatial memory creation) which demonstrates the ability of acetylcholine to be an excitatory neurotransmitter, as it enhances spatial memory. This overall explains neurotransmitters. Scopolamine plays a role in the inhibition of acetylcholine, as shown by the results due to a decrease in spatial memory encoding (as a result of inhibiting acetylcholine), which shows scopolamine to be an antagonist as it decreases the effects of the neurotransmitter acetylcholine and the likelihood of a neuron firing, overall explaining antagonist substances. Hormones: A hormone is a chemical produced by an endocrine gland. Hormones are released directly into the bloodstream and have an effect on behaviour. They activate target cells at a long distance, usually in another part of the body. The target cells have an appropriate receptor site for the hormone. When the hormone binds to the receptor in the target cell, it either increases or decreases its function. Hormones tend to have a slower effect on behaviour (from several seconds to years) when compared to neurotransmitters. The hormone adrenaline is a stress hormone that is produced in the adrenal gland. It's function is to increase heart rate, blood pressure and redistribute blood to the muscles. It plays a key role in the creation of flashbulb memories. Has an important role in our "fight or flight" response Study to use: Cahill and mcgaugh Aim: To investigate the role of adrenaline and the amygdala on emotional memory. Method: Participants divided into 2 groups, each group seeing 12 slides accompanied by a very different story. Condition 1: participant heard a boring story about a women and her son who paid a visit to the sons father in a hospital where he worked. They witness staff in a disaster preparation drill of a stimulated car accident victim.Condition 2: boy was involved in a car accident where his feet were severed. He was quickly brought to the hospital where the surgeons reattached the injured limbs. Then he stayed in the hospitals for weeks and then went home with his mother. two weeks after participating they came back and were asked questions about the story (e.g. what job did the dad have). The researchers did a follow up study, but this time, participants in the "traumatic story" condition were injected with beta blockers called propranolol. This drug will make the heart pump slower and with less force. In this study, it was used to prevent activation of the amygdala to prevent the formation of an emotional memory. Findings: In the original version of the experiment the researchers found that the participants who had heard the more emotionally arousing story demonstrated better recall of specific details of the story. They could also recall more details from the slides. In the follow up study they found that those that had received the beta blocker recalled the same amount of information as the group that had heard the dull story. Conclusion: Adrenaline and the amygdala play a significant role in the creation of memories linked to emotional arousal. Because of its role in processing emotional information, the amygdala is also involved in memory consolidation: the process of transferring new learning into long- term memory. The amygdala seems to facilitate encoding memories at a deeper level when the event is emotionally arousing. Pheromones: A pheromone is a chemical messenger that communicates information such as fertility or sexual attractiveness from one member of a species to another. A putative human pheromone is a chemical substance that is hypothesized to be a human pheromone such as androstadienone (AND) and estratetraenol (EST). Study to use: zhou Aim: Zhou et al carried out an experiment to see the effect of AND and EST on heterosexual and homosexual men and women. Specifically, they wanted the assess whether AND or EST could signal the gender of a potential mate. Method: Four groups of healthy non-smokers: 24 heterosexual males 24 heterosexual females 24 homosexual males 24 bisexual or homosexual females Participants were presented a point-light walker task (PLW), a set of dots that move in a way which represents the properties of human motion. The participants were asked to observe the stick figure in motion and to identify its gender. They performed the task at around the same time of the day on three consecutive days while being continuously exposed to either AND mixed with cloves, EST mixed with cloves, or a control solution, also mixed with cloves. The participants only carried out the task while smelling one of the solutions each day. The scents were counterbalanced to control for order effects. Findings: The researchers found that when heterosexual females and homosexual males were exposed to AND, they had a higher rate of identifying the gender-neutral walkers as "masculine" than the control group. AND had no significant effect on heterosexual men or homosexual women. By contrast, smelling EST systematically biases heterosexual males toward perceiving the gender-neutral walkers as more feminine. The effect was not statistically significant in bisexual and homosexual women. Conclusion: It appears that AND and EST may have some effect on human sexual behaviour. Specifically, these pheromones aid in identifying the gender of a potential partner based on sexual orientation in heterosexual males and females and homosexual males. Researchers concluded that Androstadienone could be a pheromone that influences mating behavior in humans. Genes: A gene is a small section of DNA on a chromosome, that codes for a particular sequence of amino acids, to make a specific protein. One gene in particular is the 5- HTT gene that transports serotonin around the body and is responsible for transporting serotonin out of the synapse and into the pre-synaptic neurons. There are two variants of the gene, a long allele and short allele, which is produced by a mutation. In western populations, the short allele leads to major depressive disorder (MDD) when people who carry it experience major life stressors. As well as this, it is thought that low levels of the 5-HTT gene is more likely to cause MDD. Diathesis- stress theories of depression predict that an individual's reaction to stressful events depends on their genetic makeup. If an individual has a specific genetic predisposition toward a disorder (genotype), then interaction with stressors in the environment may cause these genes to be expressed. Study to use: Caspi Aim: The aim of this study was to investigate the role of the serotonin transporter gene or 5-HTT gene in developing depression in response to stressful life events. Method: - longitudinal study - quasi-experiment - 847 New Zealand 26-year-olds - all were members of a cohort that has been assessed for mental health on an every-other-year basis from the age of 3 until they were 21 - divided into three groups based on their 5-HTT alleles: group 1 had two short alleles; group 2 had one short and one long; group 3 had two long alleles- the mutation of the 5-HTT gene has the shorter alleles - roughly 43% of people have the shorter alleles- they were asked to fill in a "stressful life events" questionnaire - asking them about the frequency of 14 different events (financial, employment, health and relationship stressors) between the ages of 21 and 26 - they were also assessed for symptoms of depression through an interviews - this was combined with informant reports from people nominated by each participant as "someone who knows you well" Findings: People who had inherited one or two short versions of the allele demonstrated more symptoms of depression and suicidal ideation in response to stressful life events. The effect was strongest for those with three or more stressful life events. Conclusion: It was concluded that the 5-HTT gene is responsible for controlling an individual's vulnerability to stress. Simply inheriting the gene's short mutation was not enough to lead to depression, but the genes' interaction with stressful life events increased one's likelihood of developing depression if the short allele was present. Genetic similarity: When researchers study the potential genetic origins of behaviour, one of the places to start is by looking at families because families share similar DNA (genotype). It is often said that certain behaviours "run in families." Finding evidence of this is the first step in figuring out if a behaviour might be genetic. Individuals who are more strongly related and share a larger portion of their genotype, should demonstrate more similar behaviour, provided that behaviour is inherited. Studying genetic similarity helps to determine to what extent a behaviour is genetic. Study to use: kendler Aim: To compare the genetic heritability of MDD in men and women and across historical cohorts. Method: Data was collected from over 42,000 twins (over 15,000 complete pairs) from the Swedish national twin registry. Only twins whose zygosity could be verified were used in the study. To assess lifetime MDD, a personal computer assisted telephone interview was conducted with all participants using a modified DSM-IV criteria. Informed consent was obtained prior to the interview. Trained interviewers with adequate medical background collected data. Efforts were made to reach both members of a pair within one month. Findings: They found that the average concordance rate for MZ male twins was 31 per cent and for MZ female twins 44 per cent, while for DZ twins it was 11 and 16 per cent respectively. These results indicate that depression is inherited because there are higher rates of depression in MZ twins who share 100% of their genotype than DZ twins who only share 50% of their genotype. Conclusion: Overall, Kendler et al concluded that the heritability of depression is moderate and estimated it to be 38% which was in line with previous research estimating 37%.- this study suggests both that the heritability of MDD is higher in women and that some genetic risk factors for MDD are sex -specific Evolutionary explanation: Charles Darwin's original theory proposed that individual variation which we now know is a result of genetic mutations, leads to some animals being better adapted and therefore more likely to survive. Sexual selection refers to those members of a species who have characteristics which are better suited to the environment will have more access to reproduction, passing on these traits. Any advantage an individual has in relation to reproduction is due to sexual selection. Study to use: ronay and von hippel Aim: to investigate the hypothesis that physical risk-taking by young men increases in the presence of an attractive female; and that increased risk-taking in the presence of an attractive woman might be induced by elevated testosterone Method: - 96 young adult Australian male skateboarders - mean age of 21 - recruited from skateboard parks - second part of the study: 43 were assigned to male-researcher condition and 53 were assigned to the female-researcher condition - tests were conducted between 2-6pm - first part of the study: skateboarders were asked to do one 'easy trick' and one 'difficult' trick which thet could successfully complete approximately 50% of the time. They were asked to do each trick 10 times and they were filmed by the male researcher - after a break, in the second part of the study: they were asked to make 10 more attempts of each trick but this time in front of the same male researcher or an attractive 18-year-old female researcher who was blind to the hypothesis - the attractiveness of the researcher was established by having 20 male raters view photos of potential female experimenters - the skateboarder's attempts were coded for one of three outcomes: success, crash landing, or aborted attempt - high levels of aborted attempts would be seen as an indicator of low-risk tasking - saliva samples were also collected at the conclusion of the experiment to measure for testosterone - heart rate was measured by having participants wear a Nordic sport watch - measurements were taken immediately prior to the test and then measured throughout the task Findings: participants took greater risks on the difficult tricks in the presence of the female experimenter. as predicted, testosterone levels were significantly higher among men who skateboarded in front of the female experimenter. the analysis suggests that increased risk-taking in front of the female experimenter was partially mediated by increased testosterone levels Conclusion: Young men take greater physical risks when in the presence of an attractive woman and that increases in circulating testosterone partially explain this effect.researchers also suggest that the prefrontal cortex, specifically the ventral medial prefrontal cortex (VMPFC) might play an intermediary role in these processes since the area is involved in decision making under risk.higher levels of testosterone might impair the functioning of the VMPFC, leading to higher risk-taking behavior which may hay an evolutionary origin to attract a beautiful mate.