IB Psych 2

Characteristics of hormones, and how they are different from neurotransmitters

• Hormones are released directly into the bloodstream and thus take a longer time to affect behavior than neurotransmitters

• Hormones produce effects that last a lot longer than an action potential

• Hormones can only produce reactions in certain cells, called target cells, that have an appropriate receptor site for the hormone

• When the hormone binds to the target cell, it either increases or decreases its function

• There are at least 50 different types of hormones

• Hormones are not released by the terminal buttons of a neuron. Instead, they are secreted by glands in the endocrine system

• Some hormones “act as neurotransmitters,” meaning they work in the brain by targeting receptor sites on the neuron’s synaptic gap, even though the chemical is not stored in the terminal buttons, but is secreted by an endocrine gland.

Hormones cascade

Hormones triggering more hormones

The release of adrenaline is a part of what

The hypothalamic pituitary adrenal axis (HPA Axis)

Hormonal response to threats

• When a stimulus threatens us the hypothalamus responds by activating the pituitary gland. 

• The pituitary gland then releases a hormone that activates the adrenal glands, which are located on top of the kidneys. 

• Then, both cortisol and adrenaline are released into the bloodstream.

• Cortisol dumps glucose into your bloodstream to provide energy, adrenaline increases heart rate, blood pressure, and respiration

• This has evolved to help humans survive in the face of danger so they can quickly escape an imminent threat.

McGaugh and Cahill Aim

To study the role of emotion in the creation of memories

McGaugh and Cahill Procedure

Participants divided into two groups, each saw 12 slides accompanied by a very different story. First group: participants heard a boring story about a woman and her son who paid a visit to the son’s father in a hospital where they witnessed the staff in a disaster preparation drill of a simulated accident victim

Second group: heard a story where the 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 hospital for some weeks and then went home with his mother

After watching the slides, participants were asked how emotional they found the story from 1-10. 2 weeks after participating in the experiment participants were asked to come back and their memory for specific details of the story were tested. The test was a multiple choice recognition task that consisted of a series of questions about the slides with three multiple choice options.

Researchers then did a follow up study, and the above procedure was repeated, but this time the participants were injected with either a beta blocker called propranolol or a placebo. This is a drug used to treat heart disease because the beta blockers target cells for the hormone so the heart will pump more slowly and efficiently. However, in this study, it was used to prevent activation of the amygdala.

McGaugh and Cahill Results

1st experiment: researchers found the participants who heard the more emotionally arousing story demonstrated better recall of specific details of the story. They could also recall more details from the slides. 

Follow up study: found those who received the beta blocker did no better than the group who heard the mundane story. Therefore, they concluded the amygdala plays a significant role in the creation of memories linked to emotional arousal

Applications and criticisms of McGaugh and Cahill

Applications:

The research has been applied to the treatment of PTSD patients. Pitman et al (2002) carried out a study where patients coming into emergency rooms after traumatic events such as car accidents were given beta-blockers for 19 days.  One month after the traumatic event, people who had the drug showed fewer symptoms of PTSD than similar patients who did not receive the drugs.

Criticisms:

As the recognition task only had three options, it is possible that this is not a valid test of memory. The study is artificial and highly controlled. Therefore, there is a concern about ecological validity.

Background info for Zak study

Testosterone has a permissive effect on aggression: this means that testosterone aids in the occurrence of aggression, but is not the sole cause. Additionally, testosterone increases aggression but once again, does not cause it (evidence given: baboon + mice studies). The amygdala also plays a significant role in aggression. It communicates with the hypothalamus through a cable of neurons known as the stria terminalis. When the amygdala is aroused, it sends action potentials down the stria terminalis to the hypothalamus. This is believed to be how aggression is created. Kendrick and Drewett 1979 study showed that if testosterone levels are artificially increased and amygdala is already signaling for aggression then testosterone increases the rate of action potentials in this process by shortening the resting time between each. Testosterone is also an oxytocin antagonist.

Procedure and results of Zak study

Sample of 25 male students. Researchers drew blood from participants to have the control levels of testosterone. Participants then rubbed a gel on their shoulders. With this gel, participants were given 1 of 2 conditions: a prescription testosterone gel or a placebo. Then, participants came back the next morning and another blood test was done to record the increased testosterone levels. The treatment doubled the amount of testosterone in the experimental condition. Then, participants were asked to play the Ultimatum game, where each person was told they could be generous to another player with the money they controlled, or they could be stingy. Stingy offers could be rejected by the other participant. Rejected offers caused both participants to lose all the money on the virtual table. The participants returned 4 weeks later and repeated the procedure, this time with the opposite gel to rub on their shoulders. This study was also a double blind counter balanced repeated measures design. Participants were 27% stingier when they got the testosterone gel vs. the placebo. Findings suggest the men with naturally higher testosterone levels would be expected to be more selfish and punish others if they went against the status quo. Shows testosterone has the opposite effect of oxytocin in that it causes an increase in distrust and selfish behavior.

Criticisms of Zak

Study was reductionist in its explanation of human aggression and generosity, did not measure activity in the amygdala or hypothalamus (therefore ignoring the potential influence of this), and the situation was highly artificial and thus has low ecological validity. Additionally, because the levels of testosterone were artificially manipulated and the game was very simple, this may not apply to the role of testosterone in real-life scenarios.

Neurons

Nerve cells that are the building blocks of human behavior, they send electrochemical messages to the brain so a response to stimuli can occur. Stimuli may be caused from environment or internal changes in the body.

Dendrites

Receive stimuli from environment or messages from other neurons

Cell body

Portion of the neuron that produced the energy to send the message along the axon

Axon

Carries the message from the cell body toward the next neuron

Axon terminal

Delivers the message across the synapse to the dendrites of the next neuron

Myelin sheath

Insulation which surrounds the axon, providing protection and speeding up the transmission of messages

Synapse

The gap between two neurons, where messages are passed from neuron to neuron

Neurotransmitter

A chemical substance that acts as a messenger from one neuron to another

Sleep wake cycle is how long

24 hours

What does the sleep wake cycle determine

Alertness and activity levels throughout the day and night

The internal body clock is affected by ___ and ____ factors

Internal and external

Suprachiasmatic nucleus (SCN)

Internal factor, sends messages to the pinel gland to produce and release melatonin and serotonin

Melatonin

Maintain— present throughout entirety of sleep cycle. Hormone.

Serotonin

Neurotransmitter. Start—helps one fall asleep.

Both melatonin and serotonin

Increase during darkness and are reduced during periods of light. Increased levels result in drowsiness and sleep

Zeitgeber

Major external factor related to presence of light

What has an effect on the SCN?

The detection of light by the retina in the eyes

External factors that disrupt circadian rhythm

Time zone changes, shift work, and medication

Two stages of sleep in sleep cycle:

NREM (non rapid eye movement) and REM (rapid eye movement)

During an 8 hour sleep cycle, how many sleep cycles are experienced each night?

4-5

How much of one’s life do humans spend sleeping

1/3

What tracks brain waves to show sleep vs wake states

EEG

Why is sleep needed

Restoration of energy, repair of muscles, and need for growth. Also, psychological recovery from stress, reorganization of information in the brain, and improvement of mood and mental fatigue

NREM Sleep Stages

Awake: beta and alpha brain wave activity, Stage 1: light sleep, brain waves slow down, transition from awake to sleep, theta brain waves present. Stage 2: normal sleep, theta brain waves continue, activity slowing down

REM Sleep characteristics

Eyes move rapidly under the eyelids, but the rest of the body experiences paralysis. Irregular breathing, increased HR, increased BP, higher brain wave activity (beta, alpha, and theta brain waves can be present), people experience their most vivid dreams during REM, as the sleep cycle progresses people spend less time in NREM sleep patterns, with more time in REM

Delta brain waves

Stages 3 and 4

After crossing the synapse, neurotransmitters…

Fit into receptor sites on the post-synaptic membrane. Once the message is passed on the neurotransmitters are either broken down by an enzyme or reabsorbed by the terminal buttons (called reuptake).

Excitatory neurotransmitters

Increase the likelihood of a neuron firing by depolarizing the neuron. Excitatory neurotransmitters include acetylcholine. Inhibitory neurotransmitters decrease the likelihood of a neuron firing by hyperpolarizing the neuron. Inhibitory neurotransmitters include GABA.

All neurotransmitters are agonists for

Receptor sites. They are referred to as endogenous agonists since they are biologically already part of our nervous system. Exogenous agonists refer to agonists external to our system.

Antagonists

Drugs that block the receptor site and do not allow the neurotransmitter to do its job, so no action potential is sent down the neuron.

Rogers and Kessner Aim

To determine the role of acetylcholine in the formation of spatial memory.

Rogers and Kessner Procedure

They had 30 rats acclimate to a Hebb-Williams maze by placing food in one of the corners, once the rats were familiar with the maze and no longer afraid, they began the study. The rats were randomly given one of two conditions, they were either injected with scopolamine or a saline solution 10 minutes before running the maze (scopolamine blocks the acetylcholine receptor sites and thus inhibits any response). The saline solution was a placebo. This was done to ensure injection alone was not responsible for a change in memory, as an injection could cause an increase in adrenaline which would be a confounding variable. The injections were made directly into the hippocampus. 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, whereas the average number of errors made on the first five trials of Day 2 compared to the last five trials of Day 1 was used to assess retrieval.

Rogers and Kessner Results

It was found that the scopolamine group took longer and made more mistakes in the learning of the maze (last 5 trials on Day 1). However, it did not appear to affect retrieval of memories that were already created, so the conclusion was that acetylcholine may play an important role in the consolidation of spatial memories.

Antonova Aim

To determine if blocking acetylcholine receptors in the brain can affect spatial memory tasks in humans

Antonova Procedure

Researchers used a sample of 20 healthy adult males, mean age of 28 years old. The study was double-blind, and participants were randomly allocated to either being injected with Scopolamine or a placebo 70-90 minutes before participating in the experimental task. The participants were then put into an fMRI where they were scanned while playing the Arena Task (a rather complex VR game where the researchers are observing how well the participants can create spatial memories). The goal is for participants to navigate around an arena to reach a pole. After they have learned where the pole is located the screen goes blank for 30 seconds. During this, participants were asked to recall how to get to the pole in the arena. When the arena reappeared, the participant starts at a new point in the arena. The participants then have to use their spatial memory to determine how to get to the pole. The participants were first trained in the game to make sure they were comfortable with the joystick and understood the rules. After they were trained, they then participated in the experiment. Participants' brain activity was measured for 6 trials. Participants returned 3-4 weeks later and redid the test, receiving the opposite treatment to the original study (repeated measures).

Antonova Results

When participants are injected with scopolamine, there was a significant reduction in the activation of the hippocampus compared to the placebo. This means acetylcholine could play a role in encoding of spatial memories in humans.

Rogers and Kessner MAGECC

Researchers used a rigorously controlled experiment with a placebo condition in order to avoid the effect of confounding variables, can establish cause and effect relationship, but it is a reductionist approach to understanding memory as there are many different types of memory so the process of memory consolidation is very complex, this research could one day help develop treatments for dementia or Alzheimer's, because animals were used, there may be concerns that the results of this study do not fully apply to humans

Antonova MAGECC

Insignificantly higher rate of error in scopolamine group. Significant difference in activity in hippocampus, meaning task alone may not show differences and without fMRI there would be no way to know biological differences between the two conditions. Repeated measures design eliminates effect of participant variability. Counterbalanced (different order of conditions): controlled for practice effect. Blind study: controlled for researcher bias. Several participants stressed, may have affected working of the hippocampus as stress may interfere with memory encoding. Limited sample size: needs replication to decide reliability.

Bioassay

Repeatable experiment

Chamero et al

Mouse urine + cage study, showed potential protein that may cause aggressive behavior

Hexadecanal

Putative (potential) pheromone linked to human aggression. It is a molecule that is emitted from the heads of babies

Dendritic branching

When someone learns something new, and neurons connect to create a new trace in the brain; called dendritic branching because the dnedrites of the neurons grow in nmbers and connect with other neurons.

Rosenzweig, Bennett, and Diamond (1972):

Researchers conducted experiments where they placed rats into one of two environments to measure the effect of either enrichment or deprivtion on the development of neurons in the cerebral cortex. In the enriched environment, rats were placed in cages with up to 11 other rats. In addition, there were stimulus objects for the rats to play with, as well as maze training. In teh deprived environment, the rat was alone with no stimulation. The rats spent 30 or 60 days in their respective environments and then they were killed in order to measuer the effect of the envionment on their brain structures ( :( ). Studies of their brains afterward showed that those who were in the stimulating environment had increased thickness in the cortex as a result of increased dendritic branching compared to the rats in the deprived environment. The frontal lobe was heavier in the rats that had been in the stimulating environment

Bremner (2003):

33 women participated, including women with early childhood sexual abuse and PTSD, women with abuse without PTSD, and women without abuse or PTSD. An MRI was used to measure the volume of the hippocampus in all of the participants and a PET scan to measure its level of function during a verbal declarative memory test. Women who were abused and showerd symptoms of PTSD were found to have a 16% smaller volume of the hippocampus compared to women with abuse without PTSD. In addition, these women showed a lack of activity in the hippocampus when carrying out the memory task. Women with abuse and PTSD had a 19% smaller hippocampus in volume than women without abuse or PTSD.

Maguire Aim

To demonstrate how cognitive processes may lead to neuroplasticity in the hippocampus.

Draganski Aim

To see whether learning a new skill - in this case, juggling - would affect the brains of participants

Two key findings of Maguire

Pixel counting revealed that the posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and their anterior hippocampi were significantly smaller. VBM showed that the volume of the right posterior hippocampu correlated with the amount of time spent as a taxi driver. No differences were observed in other parts of the brain.

Draganski Results

From the baseline scans, taken before the study began, they found no significant regional differences in the grey matter between the two conditions. However, at the end of the 1st part of the study, the jugglers showed a significantly larger amount of grey matter in the mid-temporal area in both hemispheres (area associated with visual memory). 3 months after the participants stopped juggling (when many were no longer able to carry out the routine) the amount of grey matter in these parts of the brain had decreased. No change in the non juggling sample.

MAGECC Maguire

- Was a quasi experiment, so no cause and effect relationship can be established, brain scans were coded so that analysis could be done blindly, some may argue that those with larger hippocampi may be more spatially talented and thus choose to be taxi drivers, however, this is disproven by the correlation between the size of the hippocampus and number of years driving. One cannot argue that the MRI has low ecological validity because the participants were not asked to do anything while in the scanner; as they were only having their brain anatomy measured. Although the study does appear to have a sampling bias, it is reality that the vast majority of London cab drivers are male. However, this does still make it difficult to generalize the findings. Finally, this study is ethically sound as the MRI does not cause any health risks and everyone gave consent.

MAGECC Draganski

- Study used a pre-test/post-test design to show differences in neural density over time, the study was experimental, thus backing a cause and effect relationship, control group present, very small sample size hurts reliability (especially considering averages were used), and because the study was a field experiment (independent variable manipulated under natural conditions), so the study has problems with internal validity as the participants were in their home environments for a good part of the study.

Primer pheromones

Pheromones that cause slow, long-term physiological changes, such as hormonal effects

Signaling Pheromones

Pheromones that produce rapid behavioral effect, such as mating

Vomeronasal organ

Located in the anterior nasal cavity of mammals, responsible for processing pheromones

Olfactory bulb

Nerves from the VNO connect to this, a special region adjacent to–but separate from–the main olfactory bulb

Population validity

The fact that most of the studies used self selected samples means that the majority of studies were performed with young, relatively educated participants

Participant bias (demand characteristics)

Participants guessing the nature of the study

Ecological validity

If it matches what naturally occurs

Internal validity

Confounding variables

Zhou et al aim

To see the effect of AND and EST on heterosexual and homosexual men and women.

Zheou et al procedure

Sample of 4 groups of healthy non-smokers, 24 heterosexual males, 24 heterosexual females, 24 homosexual males, and 24 bisexual or homosexual females. Participants were presented with a point-light walker task, which is a set of dots that move in a way that represents the properties of human motion. Participants were then asked to observe the stick figure in motion and identify its sex. Task was performed around the same time of day on 3 consecutive days while being continuously exposed to either androstadienone mixed with cloves, estratetraenol mixed with cloves, or a control solution, also mixed with cloves. Participants only carried out the task while smelling one of the solutions each day. Participants only carried out the task while smelling one of the solutions each day. Scents were counterbalanced to control for order effects.

Zhou et al results

Researchers found that when heterosexual females and homosexual males were exposed to AND, they had a higher rate of identifying the stick figure as masculine than the control group. AND had no significant effect on heterosexual men or lesbian women. In contrast, smelling EST systematically biases heterosexual males toward perceiving the stick figure as more feminine. The effect was not statistically significant in bisexual and lesbian women, showing that AND and EST may have some effect on human sexual behavior

Zhou et al criticisms

Hare et al failed to replicate the study.  This means results may not be reliable. The researchers found that exposure to putative pheromones had no significant effect on gender perception or attractiveness. Researcher carried out the experiment with different groups based on gender and sexuality and obtained different findings.  These variables must also play a role in the strength of the effect of the IV on the DV. Dose of AND and EST used in this study was notably higher than humans naturally secrete. This means that though Zhou's study showed a significant effect, it’s unlikely that this is representative.

Doucet aim

Study the role of secretion of the areolar glands in suckling behavior in 3 day old infants.

Doucet procedure

Researchers administered different secretions to the infants nasally, then measured their behavior and breath rate. The researchers then compared the infants’ reaction to seven different stimuli, including secretions of areolar glands, human milk, cow milk, formula milk, and vanilla.

Doucet results

Researchers found that infants only began sucking when exposed to the secretions of the areolar glands. Additionally, there was a significant increase in breath rate. The researchers argue that this stimulus of the areolar odor may start a behavioral and physiological events that lead to the progressive establishment of attachment between the mother and infant. 

Lundstrom and Olsson Aim

To study the effects of androstadienone (derivative of testosterone and one of the chemical components of sweat).

Lundstrom and Olsson procedure

Studied a woman’s mood after being exposed to either androstadienone or a control solution, in the presence of either a male of female experimenter.

Lundstrom and Olsson Results

Androstadienone increased women’s mood in the presence of a male experimenter and had no effect when the experimenter was female.

Hare et al aim

Study whether AND and EST signal gender and affect mate perception.

Hare et al procedure

Repeated measures counterbalanced double-blind design, heterosexual participants completed two computer based tasks twice on two consecutive days. While completing the task, on one of the days they were exposed to AND or EST, masked with clove oil, and on the other days they were exposed to the control of clove oil only. Substances were administered via a cotton ball taped under the nose throughout the task. The first computer based task involved showing the participants 5 “gender neutral facial morphs”, and participants had to indicate whether each was male or female. In the second task, participants were shown opposite sex photographs and asked to rate them for attractiveness on a scale from 1-10. 

Hare et al results

 First task revealed no difference in gender assigned to morphed faces in the pheromone vs. control condition. Results of the second task revealed no difference in the average attractiveness ratings of opposite sex photographs. Thus, the researchers concluded that AND and EST do not act as signals of gender or attractiveness, meaning they don’t qualify as sex pheromones. Additionally, the gender of the experimenter had no effect on the results. 

Cutler, Friedmann and McCoy aim

To investigate whether synthesized male pheromones increase sociosexual behavior of men.

Cutler, Friedmann and McCoy procedure

A sample of 38 men were recruited through local press releases that invited volunteers to participate in an experiment with the aim to test whether a male pheromone added to aftershave lotion would ‘increase the romance in their lives’. The selection criteria was that they were male, heterosexual, 25-42 years old, in good health, not taking any medication, of regular appearance (not abnormally attractive or unattractive), shaving regularly and having adequate social skills with women. Participants were screened with personality questionnaires to ensure they fit the criteria, anyone who had traits deviating too strongly from the average was excluded. Participants were then randomly divided into two groups (in a double-blind way). Each participant brought his aftershave lotion examined by the researchers. and was asked to use it after every shave at least 3 times a week throughout the study period. Participants were also given a behavior calendar where they had to fill out daily occurrences of 6 behaviors each day: petting, affection, and/or kissing, sleeping next to a romantic partner, intercourse, non-prearranged dates, prearranged dates, and masturbation. After a baseline period of 2 weeks, subjects then returned to he lab and the technician added either ethanol or pheromone with ethanol to their aftershave lotion. The pheromone was a synthesized version of a pheromone naturally secreted by men. Participants then used their aftershave lotion for a 6 week trial period.

Cutler, Friedmann and McCoy results

Significantly more men in the pheromone group who had an increase over the baseline in the first 4 behaviors. Researchers concluded this meant applying the synthetic pheromone resulted in an increase of sociosexual behaviors, and the attractiveness of men to women.

McCoy and Pitino aim

Investigate whether synthesized hormones have an effect on sociosexual behavior of women.

McCoy and Pitino procedure

Participants were 36 regularly menstruating women with the mean age of 28. Either the synthesized pheromone or a placebo was added to their perfume. 7 sociosexual behaviors were recorded weekly across 3 menstrual cycles, same 6 as Cutler but with the added category of male approaches. 

McCoy and Pitino results

There was a significant increase over the baseline found in the pheromone group in intercourse, sleeping next to a partner, formal dates, petting, affection, and/or kissing. There was no increase in the other 3 behaviors. Researchers concluded the synthesized pheromone increased sexual attractiveness of women to men.