51 terms

IB Psychology Biology Unit

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Principle 1
there are biological explanations for behavior
Principle 2
animal research can provide insight into human behavior
Principle 3
Human behavior is, to some extent, genetically based
B2.1 - Explain one study related to Localization of Function in the brain
behavior, emotions and thoughts originate in the brain in specific locations
Localization of Function
theory that certain areas of the brain correspond to certain functions; in that specific areas of the brain control different functions carried out by the brain
1. Corkin
Aim: to determine the extent of damage done to HM's brain

Method: performed an MRI on HM

Findings: All of HM's hippocampus and amygdala were removed

Conclusions: the hippocampus is responsible for the storage of new memories

Critical thinking: ethical? reliable?
2. Maguire (2000)
Aim: to investigate whether or not the hippocampus plays a role in human spatial memory.

Method: London taxi drivers w/ a range of age & experience were participants because their work requires the extensive use of spatial navigation skills. Participants were age & gender matched w/ a control group

Findings: showed significantly more grey matter in both left and right hippocampi of the taxi drivers compared to the control group.

Conclusions: Localization of Function, neuroplastisity
B2.2 - Using one or more examples, explain the effects of neurotransmission on human behavior.
Neuron
Neurotransmission
Neurotransmitters
Significance of neurotransmitters in the BLA?
Neuron
nerve cells - 1 of the building blocks of behavior
send electrochemical messages to the brain so that people can respond to stimuli: either external stimuli (environment) or from changes in the body.
Neurotransmission
the method by which messages are sent through the central nervous
when an electrical impulse travels down the axon, it releases neurotransmitters which cross the gap between 2 neurons, synapse.
Neurotransmitters
the body's natural chemical messengers which transmit information from 1 neuron to another.
stored in the neuron's terminal buttons
after crossing the synapse, neurotransmitters fir into receptor sites on the post synaptic membrane
once the message has been passed on, they are either broken down or reabsorbed by terminal buttons, reuptake.
What is the significance of neurotransmitters in the BLA?
neurotransmission underlies behavior as varied as mood, memory, sexual arousal and mental illness
Acetylcholine (ACH) on memory
ACH is a neurotransmitter which had been linked to motor movement and to synaptic plasticity in the hippocampus and it seems to play an important role in learning and short-term memory via the cholinergic system (system of nerve cells that uses ACH in transmitting nerve signals)
Martinez & Kesner (1991)
Aim: determine role of ACH on memory

Method: 3 groups of rats trained to go through maze, received food if they went through
1st - blocked ACH w/ scopolamine = less ACH
2nd - blocked "clean-up" of ACH= excess ACH
3rd - control group/no injection, normal ACH

Findings: less ACH = more errors; more ACH = fewer errors

Conclusions: ACH played a key role in creating a memory of the maze

Critical Thinking: ACH helps improve memory
Dopamine
Released in the brain's reward system and has been associated with pleasure seeking and addictive behavior. Addictive drugs or substances increase the amount of dopamine in the reward system
Can be released by environmental triggers b/c this is associated with pleasure
Fisher et al. (2003)
Aim: Being "in love" is similar to being "addicted"

Method: Took 40 young ppl, 20 with love returned and 20 with love rejected. Showed them pictures of their sweetheart & just an acquaintance off and on for 30 seconds each for 12 minutes. Gave them fMRI while showing the pictures

Findings: Increased blood flow where areas of the brain flood dopamine when love was reciprocated - similar activity w/ cocaine. Decreased in those rejected.

Conclusions: Love seems to be an emotion but a drive to seek pleasure Hormone study
B2.3 Using one or more examples, explain functions of 2 hormones in human behavior.
Hormones - the endocrine system of glands in the human body secretes these chemicals. Controlled by the hyppothalamus
Cortisol
Hormone produced by the adrenal cortex in response to stress and to restore homeostasis.
Newcomer et al. (1999)
Aim: To investigate how levels of cortisol interfere w/ verbal declarative memory.

Method: A self-selected sample (thru an ad) of 51 normal and healthy people ages 18-30 was used. Randomized, controlled & double-blind.
3 conditions-
1.) high level of cortisol (160 mg tablet) given, same as cortisol released in a stressful event.
2.) low level cortisol (40 mg), same as a minor stressful event
3.) placebo

Findings: High level group performed worse on verbal memory test than the low level and placebo group. Low level group showed no memory decrease.

Conclusions: It was controlled and randomized so it was possible to establish a cause and effect relationship. They received informed consent. Hormone Study
Oxytocin
Secreted by the hypothalamus and released (1) into the blood stream via the pituitary gland or (2) into the brain and spinal cord where it binds to oxytocin receptors.
Acts primarily as a neurotransmitter in the brain.
Linked to trusting other people
Baumgartner et al. (2008)
Aim: the role of oxytocin after breaches of trust in the trust game

Method: Participants played a trust game used by scientists to study social interaction. "Investor" (player 1) gets a sum of money and must decide whether to keep it or share it w/ a "trustee" (player 2), what is shared is tripled. Player 2 must decide if the sum should be shared (trust) or kept (violation of trust) fMRI scans. Received oxytocin or placebo through a nasal spray

Findings: Placebo group showed less trust after betrayal. Oxytocin group continued to invest at similar after betrayal. fMRI scan showed less responses in amygdala and caudate nucleus.

Conclusions: Oxytocin could explain why ppl are able to restore trust and forgiveness in long-term relationships fMRI gave an idea about possible correlation but gave nothing definite about cause and effect. Hormone Study
B2.4 - Discuss 2 effects of the environment on physiological processes
...
Effect 1: Brain Plasticity
Environmental stimulation (social interaction and learning opportunities for animals & humans) result in increased numbers of synapses.
Rosenzweig and Bennet (1972)
Aim: to investigate whether environmental factors (rich or impoverished) affect development of neurons on the cerebral cortex.

Method: rats were placed in either an enriched environment (EC) or an impoverished condition (IC).
EC- 10-12 rats in a cage proved w/ different stimulus objects to explore and play with, received maze training.
IC- each rat in an individual cage (isolation and no stimulation)
Rats spent 30-60 days in their respective environments before they were killed so the researchers could study changes in the brain anatomy.

Findings: anatomy of the brain was different for rats in the EC & IC. Brains of EC rats had increased thickness and higher weight of the cortex (frontal lobe), had developed more ACH receptors in cerebral cortex

Conclusions: (issues) difficult to generalize to humans
research challenged the belief that brain weight cannot change.
ethics- rats were killed
What is an enriched environment?
Maguire - link to plasticity
longer the taxi driver the greater the volume, stimulated environment did affect hippocampus --- plasticity
Effect 2: Long-term exposure to violence (bullying)
individuals who are exposed to violence short-term or long-term will typically exhibit a stress response that includes fear and physiological arousal partly due to secretion of stress hormones and activation of the amygdala.
Carney and Hazler (2007)
Aim: to investigate changes in cortisol levels in relation to bullying

Method: took saliva tests from 94 sixth graders (ages 9-14). Students filled out a questionnaire on their experience of being bullied or being a bystander. Cortisol levels were tested in the morning and before lunchtime (a period associated with bullying)

Findings: anticipation of bullying was associated with high levels of stress and anxiety in both victims and bystanders. Long-term exposure to bullying was related to lower levels of cortisol. This condition is associated with Chronic Fatigue Syndrome and PTSD.

Conclusions: Cortisol levels increase when a person experiences a short-term exposure to bullying. This affects learning and memory. Long-term bullying and low levels of constant cortisol secretion may have more enduring negative consequences on physical, social, & psychological health.
Newcomer - link to bullying
memory - bullying affects cortisol levels because of stress which affects learning and memory.
B2.5 Examine one interaction between cognition and physiological processes
Cognitive neuroscience is the scientific study of biological correlates of mental processes (cognition). This area of research investigates how various brain areas involved in the cognitive processes.
Maguire link
stimulated environment did affect hippocampus of taxi drivers-- plasticity in brain-- greater volume in hippocampus
Newcomer link
high cortisol levels affects memory, making it more difficult to remember -- verbal tests
Martinez and Kesner link
less ACH = more errors in a maze (rats) -- affect on memory
B2.6 Discuss the use of brain imaging technologies in investigating the relationship between biological factors and behavior
brain imaging is used to investigate the relationship between behavior and brain structures.
MRI scan
give detailed pictures of internal structures in the body
Maguire Link
the MRI gave insight to the biology, grey matter having significantly more volume, affected the way the taxi drivers performed on their jobs.
HM link
The MRI showed, since HM had much of his hippocampus removed, it affected his memory and his everyday lifestyle.
fMRI scan
measures changes in blood flow in the active brain.
Fisher et al. Link
the scan provided insight to a biological process being affected by an environmental factor
Baumgartner link
fMRI scan gave an idea about a possible correlation between the oxytocin and the actions then performed by the participants.
B3.1 With reference to relevant research studies, to what extent does genetic inheritance influence behavior?
Gene mapping - attempt to determine the effect of a particular gene on behavior such as psychological traits, psychological disorders, or various physiological conditions.
1.) Twin Studies
In twin studies, sets of MZ twins are compared to sets of DZ twins for a particular trait disorder.
Monozygotic Twins (MZ)
identical twins, come from the same egg and share 100% of their genes.
Dizygotic Twins (DZ)
fraternal twins, come from 2 different eggs and share around 50% of their genes, like any other sibling would.
Concordance Rates
Likelihood or probability that is one individual has the trait the other will also have it.
Bouchard et al. (1990)
Aim: Twin study investigating genetic inheritance in intelligence.

Method: This study used a self-selected sample of MZ twins who had been reared together (MZT) and MZ twins who had been reared apart (MZA). Each twin completed approximately 50 hours of testing on nearly every human dimension. Used the WAITS to measure intelligence.

Findings: Concordance rates for MZA was 69% and for MZT was 88%. 70% of the observed variation could be attributed to genetic variation.

Conclusions: environmental factors do play a role in development of intelligence, but IQ is to a large extent inherited. Correlation data cannot establish cause/effect relationships. Rates were high but far from 100%.
2.) Genes and Sexuality
The role of genetics in the study of human behavior has been very influential.
Bailey & Pillard (1991)
Aim: To investigate the genetic basis of sexual orientation.

Method:
- Recruited a voluntary sample of male MZ twins,DZ twins, and adopted brothers through gay publications. All siblings were raised together.
-Found out sexual orientation of relatives by wither asking directly or asking the gay participants.
-Researchers used questionnaires to assess the participants' levels of childhood gender non-conformity (CGN)

Findings:
-52% of MZ twins were both self-identified homosexuals (SIH).
-22% of DZ twins were SIH. 11% of non-related adopted brothers were SIH.
-Non-twin brothers had 9.2%.
-The closer the genetically linked the more likely it is to exhibit gay or straight tendencies. Childhood gender non-conformity did not predict homosexuality.

Conclusions:
-Not randomly selected.
-Data was self-reported = unreliable.
-Information given was retrospective.
-Being homosexual is hard to standardize.
-Small sample size (only males).
-Environment was not taken into account.
-Correlation ≠ causation
-Consent was obtained = yes it was ethical.
B3.2 Examine one evolutionary explanation of behavior.
The theory of evolution, suggested by Charles Darwin, is based on the assumption that living organisms face environmental challenges.
Partner selection based on genes
Natural selection would favor couples that have genes which mutually enhance their offspring's chances of survival. This could be one way to select a "preferred partner".
Wedekind (1995)
Aim: Investigating mate preference based on genetic makeup in relation to immune system functioning.

Method:
-Group of 94 students (half male, half female).
-Men were asked to sleep with a t-shirt for 2 nights and keep it in a plastic bag.
-After 2 days the women were asked to rate how agreeable they found the smell of the t-shirts (smelled 7 different shirts - 1 was a control)

Findings: Women preferred the odors of men with an immune system dissimilar to their own.

Conclusions: This lends support to the evolutionary explanations of mate selection in humans. Attraction is influenced by biological factors. Women preferred the scent of men with a genetic makeup that could increase the health of potential babies.
Shackelford & Larsen (1997)
Found that men with less symmetrical facial features were less physically active, manifested more symptoms of depression and anxiety, and reported more minor physical problems - for example, colds, headaches, and gastrointestinal problems. It appears that asymmetrical facial features develop during puberty. Chronic illness during adolescence can suppress androgen secretion, leading to lower physical attractiveness. Thus it is argued that we find symmetrical features more attractive.