Biological Psychology

Neurotransmitters

• One way messages are passed within the brain

• Chemicals that pass from neuron to neuron.

• Between neurons there are gaps called synapses.

• If the receptors of one neuron are set to receive the neurotransmitters of another, the message continues.

Genes

• Are passed on from parents to children + they govern behaviour as well as physical characteristics.

• Children receive roughly half their genes from their fathers + half from their mothers.

• The human genome has recently been decoded - means that all genes have been identified.

• Does not mean the function of each gene is known - it is often the combination or the position of genes that leads to certain characteristics, not one particular gene.

Seasonal Affective Disorder

• Type of depression

• Linked to the change in seasons

• Typically occurs during winter + autumn months

• Decreased exposure to natural light can disrupt our circadian rhythms

Exogenous zeitgebers

External factors that help regulate our circadian rhythms e.g light exposure

Hormone implicated in the cause of SAD

• Melatonin

• Pineal gland secretes melatonin until dawn (increase in light)

• During winter secretion process continues for longer

• In turn decreases production of serotonin - linked to depressive symptoms

SAD - treatments

• Light therapy

• Anti - depressants (SSRIs)

Infradian Rhythm examples

• Menstrual cycle

• SAD

The menstrual cycle

• 28 day series of physiological changes that occur in a woman’s body to prepare for a possible pregnancy

• Controlled by the interaction of hormones produced by hypothalamus, pituitary gland + ovaries

• Divided into 3 phases

4 phases of the menstrual cycle

• Menstrual phase

• Follicular phase

• Ovulation

• Luteal phase.

Menstrual phase

• First phase

• Lining of uterus shed through vagina

• 3 - 7 days

Folicular phase

• Second phase

• Pituitary gland releases FSH

• This stimulates the growth of a follicle in the ovary

• The follicle contains the egg

• As the follicle matures, it releases oestrogen

• Oestrogen causes uterus to thicken lining to prepare for pregnancy

• 14 days

Ovulation

• Third phase

• Mature egg is released from follicle

• Egg ready for fertilisation

Luteal phase

• Final phase

• Egg released from ovary

• Ovary produces progesterone

• Progesterone thickens uterus lining to prepare for pregnancy

• If egg is fertilised + implants in uterus, fertilised egg produces hCG

• hCG maintains thickened lining of uterus

• If pregnancy does not occur, thickened lining is shed (menstrual phase)

Premenstrual Syndrome (PMS)

• Associated with luteal phase

• Oestrogen + progesterone levels rise to prepare endometrial lining for embryo

• If conception does not occur, levels of hormones decrease towards end of luteal phase

• Lining + unfertilised egg are shed (menstruation)

• Levels of other hormones also rise + fall

• Typically occur 5 days before menstruation + end 4 days after bleeding starts

• No more symptoms until day 13

PMS symptoms

• Acne

• Back ache

• Cramps

Reinberg - Menstrual cycle

• Exogenous zeitgebers

• Light exposure can affect menstrual cycle

• When women were exposed to bright light in the evening, menstrual cycles became shorter

• Woman spent 3 months in a cave with only a small lamp

• Cycle shortened from 28 - 25.7 days

• Shortened luteal phase

Russell et al. - Menstrual cycle

• Pheromones

• Menstrual cycles became synchronised with other females’

• Through odour exposure

• Sweat samples from one group of women were rubbed on upper lip of another group of women

• Despite physical separation from the other group, menstrual cycles synchronised

• Pheromones have an effect on people nearby rather than those producing them

• External factors do effect infradian rhythms

• A more holistic approach should be taken not reductionist considering only endogenous factors

Evolutionary psychologists - Menstrual cycle

• Synchronisation of menstrual cycles provides evolutionary advantages

• Allows better coordination + cooperation among women in group

• Allows better care for children + hunting for food

• May also increase social bonding

• Beneficial in terms of forming alliances + support networks, important for survival

Penton - Volk et al - menstrual cycle

• Conducted research on relationship between menstrual phase + social behaviour in women

• Women in luteal phase (after ovulation) were more likely to engage in prosocial behaviours e.g helping others

• Compared to women in follicular phase (before ovulation)

• Women expressed a preference for feminised faces at the least fertile stage of menstrual cycle + more masculine face at most fertile stage

• Infradian rhythms play a role in regulating behaviour

Light therapy - evaluation - Eastman

• After 3 weeks of light therapy symptoms significantly decreased

• Therapy resets the circadian rhythm

• Suppresses melatonin + reduces symptoms

SAD - research - Golder + Macy

• Analysed 509 million twitter messages

• Across 84 countries

• Found a relationship between decreased day length + less positive emotions

SAD - research - Dongdong Qin

• Reduced daylight in a group of 8 macaque primates

• Increase in depressive symptoms

• E.g huddling, reduced movement + weight loss

• Reversed with antidepressant treatment

SAD - research - Lam et al.

• Review of 22 studies

• Looked at relationship between latitude + prevalence of SAD

• Correlation of 0.66

• Consistent with shorter days experienced in north compared to south being associated with SAD

• However, those not affected by SAD are likely to remain north

• Those affected by SAD are more likely to migrate south.

Light therapy - SAD

• Decreases levels of melatonin

• Uses light box to increase amount of light received

• Decrease in melatonin reduces tiredness + can reduce symptoms

• Most effective in morning

• 10,000 lux intensity

• 30 inches away from eye level.

• 30 - 60 minutes of white light

Light therapy - evaluation - Reeves et al.

• Self report scores for depression fell after 1 session

Light therapy evaluation

• Often used alongside other treatments (antidepressants + psychotherapy)

• Because light therapy may only work short term

• May not prevent SAD from reoccuring in the future, so not a cure

• More of a management tool not an effective treatment

Light therapy - side effects

• Non-invasive, safe + easy to use

• No serious side effects unlike antidepressants

• Can have mild side effects e.g insomnia + eye strain, headache or agitation

• Not recommended for individuals with certain eye conditions

Light therapy - evaluation - convenience

• Convenient - requires no preparation or recovery time and can be done at any time of day

• Can be unsafe for some people so not be suitible for everyone e.g those with eye conditions

• Must be done consistently every day, may be difficult for some individuals to maintain

• Light boxes can be expensive

Light therapy alternative - Antidepressants

• SSRIs

• Increase serotonin in the brain

• Help improve mood in winter months

• Stop serotonin being taken out of synapse by uptake mechanisms

• Taken as a tablet, begin at smallest possible dose to improve feelings of depression

Light therapy alternative - Psychotherapy

• CBT

• Fewer physiological side effects

• May be less distressing to patients

• Can take up to 6 weeks to be effective

• Light therapy treats symptoms whilst CBT changes our thought process

• CBT shuld last long term so is more effective as it addresses reasons behind symptoms

Steps of melatonin release

• Low levels of light (retina)

• Melanopsin carries signal to SCN

• Axon pathway to pineal gland

• Melatonin release

• Induced sleep

Effect of shift work - Circadian rhythm

• Involves waking at times when you should be asleep

• Causes breakdown between endogenous pacemakers + exogenous zeitgebers

• Maybe because external cues are apparent when trying to sleep - interrupts melatonin production

• Alternating shift patterns further disrupt routines for eating + sleeping

• State of desynchronisation - decreased alertness + concentration

• Can cause health problems - cancer + heart disease

• Lowers productivity causing depression + anxiety.

• E.g Chernobyl disaster occured between 1-4am which may have been caused by shift work

Shiftwork - research

• Roughly $77 billion spent on major accidents or work related illnesses due to shift work

• Knutsson et al - found people who worked shifts for more than 15 years were 3x more likely to develop heart disease than non-shift workers.

Shiftwork research - Czeisler

• Advised a Utah chemical plant on shift patterns

• Original = 3 typical 8 hour shifts on backwards rotation

• Workers reported = stress + trouble sleeping, high levels of absenteeism + minor health issues

• Rotated shifts every 21 days - allows time for cycle synchronisation (forward rotation system)

• After 9 months = workers reported lower stress + absenteeism + increased productivity

Shiftwork research - Police

• Supports Czeisler

• Research on American police officers

• Moving shifts to forward rotation decreased stress accidents while working by 40%

• Our knowledge of circadian rhythm allows us to devise methods to reduce effects of shift work

Shift work - evaluation - gender bias

• Males make up majority of shift work

• Most research has involved mainly male participants

• Results may not apply to females due to different anatomy + hormones

Shift work - evaluation - ethics

• Raises ethical issues - should shift work be allowed

• Suggests their may be long-term negative consequences

Shift work - evaluation - real life application - rotating shifts - Gold

• Found more problems occur when shifts rotate rapidly

• By rotating them over a longer period of time, we could reduce harmful bodily effects

• Body given time to adjust to the new pattern

Shift work - evaluation - real life application - Herxheimer + Petrie

• Reviewed 10 studies + found taking melatonin near bed time was effective in inducing sleep

Jetlag

• Physiological effects of a disrupted circadian rhythm caused by travel

• Caused when people travel across time zones so endogenous pacemakers do not match exogenous zeitgebers

• Biological rhythms - not able to cope with sudden changes
  - SCN is resistant to exogenous zeitgebers + takes several cycles to fully synchronise

Jetlag - evaluation - Schwartz et al

• Studied US baseball teams who travelled across the country for matches

• Teams going from east coast to west experienced clocks going 3 hours back (phase delay)

• West coast teams experienced (phase advance)

• Significant difference between their win rates

• East to west = won 44%

• West to east = won 37%

• Lacks internal validity = confounding variables (illness, referee bias)

Jetlag - evaluation - real life application - Webb + Agnew

• Found succesful strategies for coping with jet lag

• Outdoor pursuits, light exposure + regular meal times

• Suggests following exogenous zeitgebers is the best way to address jet lag consequences

Jetlag - evaluation - real life application - melatonin

• Effectiveness of jetlag treatments allows us to understand endogenous pacemakers + exogenous zeitgebers

• Melatonin is being developed as a treatment

• Reports suggest it is useful in resetting endogenous pacemaker

• Small doses taken a few hours before local bedtime

• Effects vary depending on if jet lag symptoms are due to phase advance or phase delay

Endogenous pacemakers - research - Decoursey + Krulas

• Used radio collars on chipmunks - measure survival rates in Allegheny mountains, USA

• Surgically damaged SCNs of chipmunks

• Lost normal rest-activity cycle

• 30 = surgical lesions to SCN

• 24 = surgery not on SCN

• 20 = intact controls

• SCN Lesioned = higher proportion killed by weasels in first 80 days of release.

• Due to increased nocturnal movements - attracted weasel predators

• Shows significance of SCN + endogenous pacemakers on circadian rhythm

Exogenous zeitgebers - research - Siffre

• 7 months underground in a cave

• No exogenous zeitgebers (temperature, social contact + light)

• Circadian rhythm increased from 24 - 25 hours

• Significance of exogenous zeitgebers on circadian rhythm

Endogenous pacemakers - research - Morgan

• Bred hamsters to have a circadian rhythm of 20 hours (not 24)

• SCN neurons were transplanted into normal hamster brains

• Circadian rhythm adjusted to 20 hours

• Significance of SCN on circadian rhythm

Exogenous zeitgebers - research - Skene + Arendt

• Claimed the majority of blind people with some light perception have normal circadian rhythms

• But, those without any light perception show abnormal circadian rhythms

• Significance of exogenous zeitgebers on circadian rhythm

Circadian rhythm

• Lasts 24 hours

• Sleep-wake cycle

• Runs on a combination of endogenous pacemakers + exogenous zeitgebers

• SCN - part of hypothalamus - regulates sleep-waking patterns by sending messages to the pineal gland

• Humans have a free running 25 hour endogenous pacemaker - kept to 24 hours by exogenous zeitgebers

Hormones

• Body’s chemical messangers

• Transfer information around the body through bloodstream

• Produced by endocrine system

• Affect many processes (growth, reproduction + mood)

Testosterone

• Androgen - chemical that develops male characteristics

• Antenatal exposure can impact developing brain

• Increased competitive aggression

• Too much testosterone after birth - increases cell growth in hypothalamus + amygdala

• Increases aggression

Chang et al - hormones

• More testosterone in fish = more aggresive

• Measured by aggression, exploring + boldness

• Aggression = readiness to display gills to mirror image

• Exploring = readiness to explore shelter

• Boldness = readiness to leave shelter

• When these traits increased, so did testosterone levels

Wagner et al - hormones

• Castrated mice = aggression levels dropped

• Injected with testosterone = aggression increased

• Aggression measured by biting attacks on other mice

• Testosterone causes aggression in mice

• Issues of extrapolation

Dabbs et al - hormones

• 692 adults males

• Prison inmates

• Testosterone measured in saliva samples

• Behaviour was coded through previous prison system records

• Those who had commited sex + violence crimes = higher testosterone

• Those who had commited burglary, theft + drug crimes = lower testosterone

• Higher testosterone = violated more prison rules, especially rules involving confrontation

Oxytocin - release

Posterior pituitary gland

Oxytocin

• Hormone - increases trust between people

Oxytocin - Low levels

• Decrease trustworthiness

• Increase aggression

Oxytocin - Lane et al - Hormones

More oxytocin = increase in trustworthiness

Cortisol - production

Hormone produced in adrenal glands

Cortisol

• Responsible for waking us up in the morning

• Main job = manages stress levels

• Inhibits aggression

Cortisol - Low levels

• Under aroused autonomic nervous system (ANS)

• To increase arousal - become aggressive

Burnett et al

Boys with lower cortisol levels in saliva = 3 times more aggressive than those with high levels

Selective breeding - Genes + aggression

• Using selective breeding, psychologists have found aggression can be transmitted from parent to offspring

• Supports genetic explanation

Monozygotic twins

• Genetically identical

• Split from same egg shortly after conception

• Share 100% of genes

• Always same sex

Diozygotic twins

• Genetically non-identical

• Developed from seperate eggs

• If same sex = share up to 50% of genes

Concordance rates - twin studies

• Used to measure twin studies

• If 100% = all twins have a behaviour in common

• If 0% = no twins have a behaviour in common

• Psychologists compare concordance rates of MZ and DZ twins

• Determine extent that behaviour is a result of environment + genetics

If MZ concordance is significantly higher than DZ concordance

The disorder has a genetic component.

If MZ concordance is same or similar to DZ concordance

The disorder is environmentally caused.

If MZ concordance is 100% 

The disorder is genetically caused.

If MZ concordance is significantly less than 100%

The disorder has an environmental component.

Coccaro et al - genes - hypothesis

MZ twins would have greater similarities (higher correlation) than DZ twins in aggressive behaviour (if aggression was influenced by genes).

Coccaro et al - genes - results - direct physical assault

MZ twins = 50% concordance rates

DZ twins = 19% concordance rates

Coccaro et al - genes - verbal assault

MZ twins = 28% concordance rates

DZ twins = 7% concordance rates

Coccaro et al - genes - conclusion

There is a significant influence of genes on aggression

Brengden et al - genes

Study of 6 year old twins + physical aggression

Brengden et al - genes - results - physical aggression

MZ correlation = almost twice as high as DZ twins

• Suggests physical aggression is mainly influenced by genetic factors

Brengden et al - genes - results - social aggression

Correlation was similar for MZ and DZ twins

Suggests social aggression is more influenced by shared environmental factors

Brengden et al - genes - results - non-shared environmental factors

- Influence both physical + social aggression

- In neither case was the correlation high

Twin studies - evaluation - shared enviornment

• MZ twins typically brought up in shared environment + same prenatal environment

• Difficult to determine if behaviour is genetic or due to same enviroment

Twin studies - evaluation - concordance rates

If MZ concordance rates don’t equal 100%, twin studies cannot provide conclusive evidence of genetic influences.

Twin studies - evaluation - sample

• Small sample sizes as twins are rare

• Findings unrepresentative of wider population

• Difficult to recruit large + diverse sample of MZ and DZ twins

• Difficult to generalise

Brendgen et al - aims

• Extent social aggression is explained by genetic factors, shared environmental + non-shared environmental factors compared to physical aggression.

• If any covariance between physical + social aggresion can be explained by shared genetic factors, shared environmental factors or non-shared environmental factors. Or if it can be explained by effects of one type of aggression on the other.

Brengden et al - Sample

• 234 pairs of 6 year old twins

• From Montreal, Canada

• 84% from European descent

• Same sex = assessed for physical resemblance (18 months) - determine if MZ or DZ - many were also checked through DNA

Brengden et al - Procedure

6 years old

- data collected to assess social adaptation in kindergarden

- written consent received from parents before data collection

- Peer reports + teacher ratings also collected

Brengden et al - procedure - Teachers rated social + physical aggression of twins in class

- Used Preschool social behaviour scale + indirect aggression scales (psychometric tools)

- Measured extent teachers rated children as (making others dislike a child, becoming friends with another child in revenge, spreading nasty rumours)

- Physical = (times children got into fights, hit, bit or kicked others + physically attacked others.

Brengden et al - procedure - Peer reports

Children asked to circle 3 children who best fit behaviour descriptions on a photo

Social aggression measured:

- ‘tells others not to play with a child’, ‘tells mean secrets about others’

Physical aggression measured:

- ‘gets into fights’, ‘hits, bites or kicks others’

Brengden et al - results - social aggression - genetics

Teacher ratings = 20%

Peer ratings = 23%

Brengden et al - results - social aggression - shared environment

Teacher ratings = 20%

Peer ratings = 23%

Brengden et al - results - social aggression - non-shared environment

Teacher ratings = 60%

Peer ratings = 54%

Brengden et al - results - physical aggression - genetics

Teacher ratings = 63%

Peer ratings = 54%

Brengden et al - results - physical aggression - shared/non-shared enviornment

Teacher ratings = 37%

Peer ratings = 46%

Brengden et al - findings - physical aggression

- MZ = correlation twice as high as for DZ

- For both peers + teachers

- Genetic factors = main influence on physical aggression

- Shared environment = little influence on physical aggression

Brengden et al - findings - social aggression

- Correlation for MZ and DZ were similar

- For both peers + teachers

- Shared environmental factors = main influence

Brengden et al - findings - non-shared environmental factors

- Influence social + physical aggression

- As correlation was not high for either

Brengden et al - conclusion - physical aggression

- Influenced by genetic factors + non-shared environmental factors

Brengden et al - conclusion - social aggression

- Mainly influenced by environmental factors

- Mainly non-shared environmental factors

MAOA gene (warrior gene) - dysfunction - adrenaline

- Noradrenaline not being broken down

- Too much adrenaline (not metabolised)

- Hypersensitivity in fight or flight response

- May overreact to external stimulus + perceive a threat that does not exist.

MAOA gene (warrior gene) - dysfunction - dopamine

- Increased levels of dopamine (not broken down)

- Excess levels of dopamine linked to aggressive behaviour

MAOA gene (warrior gene) - dysfunction - serotonin

- Decreased levels

- Has a calming influence

- Low levels = reduction of control over impulses

Stuart et al - MAOA - hormones

- 97 men

- All involved in severe domestic abuse to partners

- The most violent men had faulty MAOA gene

- They engaged in highest level of physical + psychological aggression

- Inflicted worst injuries on partners

McGuffin & Gottesman - twin studies

MZ twins aggression concordance rates = 87%

DZ twins aggression concordance rates = 72%

- Genes influence aggression

- As MZ was not 100%, other factors also influence aggression