BIOLOGICAL APPROACH

MRI

magnetic resonance imaging

• uses a strong magnetic field & radio waves to create a detailed 3D image of the body’s internal structures

• magnetic field aligns the protons in the body (mainly from water molecules)

• MRI sends pulses of radio waves, disrupting the alignment

• as protons return to the original spot, they release energy, allowing the MRI machine to detect the signals and generate images

Maguire et al. (2000) AIM

to investigate whether the brain of London taxi drivers is structurally different due to their navigational experience

Maguire et al. (2000) METHOD

quasi-experiment

• allows cause-and-effect relationship to be established

• participants are allocated based on pre-existing characteristics

• IV was not manipulated, as pre-existing groups were compared

• range of ages

• single blind study (participants were blind)

Maguire et al. (2000) SAMPLE

16 right-handed taxi driver males who had their license for at least 1.5 years

Maguire et al. (2000) PROCEDURE

• 50 control males were placed in an MRI machine to create a baseline

• taxi driver males were also placed in an MRI

• machine used 2 techniques

  • voxel-based morphometry (VBM) - measures density of gray matter

  • pixel counting - measure the area of the hippocampus

Maguire et al. (2000) RESULTS

• pixel counting showed the posterior hippocampi was larger in taxi drivers

• volume of right posterior hippocampi varied depending on time spent as a driver

  • longer = larger

  • shorter = smaller

• anterior hippocampus was smaller

Maguire et al. (2000) CONCLUSION

• posterior hippocampus is involved when previously learned spatial info is used & may change in response to environmental demand

• anterior region may be involved in encoding new environmental layouts

localization of function - the hippocampus

localization of function: the notion that specific areas in the brain are responsible for certain behaviours

can be studied through

• relative localization: there is a dominant area but is not the only area

• strict localization: specific parts are strictly for certain behaviours

• equipotential theory: all areas of the brain are always active and equally active in overall mental functions

  • basic skills are localized but complex things are combined

• hippocampus - located deep within the medial part of the temporal lobe of the brain, one in each hemisphere. It sits near the temples and ears and is a key structure for memory and spatial navigation

hormones - cortisol

hormones: chemicals released by specific glands in the body that circulate in the bloodstream & act as messengers to organs and cells

• regulate medium and long-term behavioural changes but take a long time to do so

• may act as neurotransmitters as well & can be more instantaneous in their impacts

cortisol

• produced in the adrenal glands

• increases amount of glucose in the blood & increase the metabolism of fats, proteins, and carbs

• provides crucial energy for the fight or flight response

• moderate levels help the consolidation & retrieval of memory

• high levels impair memory & can lead to hippocampal impairment

Newcomer et al. (1999) AIM

investigate whether high levels of cortisol interfere with verbal declarative memory

Newcomer et al. (1999) METHOD

double blind true experiment

• participants were matched for age & gender

IV - cortisol

DV - verbal memory performance

high level of cortisol - given a tablet w/ 160mg on each day

low level - given a tablet with 40mg

placebo - given a fake tablet

Newcomer et al. (1999) SAMPLE

employees/students at Washington University Medical Center who were checked to ensure no health conditions that would interfere

Newcomer et al. (1999) PROCEDURE

asked to listen to & recall parts of a prose paragraph for 4 days to test verbal declarative memory

Newcomer et al. (1999) RESULTS

high cortisol - impaired memory performance (worst of three)

• effect didn’t last

moderate - assisted in recall of the passage

there are cortisol receptor sites on the hippocampus, responsible for the transfer of info & allowing them to do better

neuroplasticity

the ability for parts of the brain (synapses & pathways) to change their structure based on changes inside and outside the body

• dendritic branching causes it as the dendrites of neurons grow as we learn new things

synapse - the tiny gap between two neurons where communication happens (where the axon terminal & the dendrite meet)

• axon terminal is the end part of the neuron that releases chemical messages

• dendrite receives the message

• long term potentiation - when synapses become stronger due to repeated use

• neural pruning - when synapses are removed as they are under used/stimulated

neural networks - when neurons connect with others to form connections (shaped by neuroplasticity) and provide a path for signals and connections

• received by sensory organs and travel to desired location

• more its used, the more efficient and developed it becomes

evolution

the changing in the inherited traits of a species over time (Charles Darwin)

evolutionary psychology - a theoretical approach that assumes human thoughts, feelings & behaviours have been exposed to evolutionary pressures

• natural selection: members of a species who have characteristics which are better suited to the environment will be more likely to breed & pass traits

  • results in successive generations developing characteristics that make it more competitive

Fitness refers to the organisms ability to survive and reproduce within their environment. 

• Evolutionary psychologists attempt to explain how certain behaviors can be explained by examining their evolutionary origins and identifying their ability to enhance survival. The evolutionary theory of natural selection can be used to explain various emotions, such as disgust.

Fessler et al (2005) AIM

investigate if disgust sensitivity varies during pregnancy

Fessler et al (2005) METHOD

31 item true/false & likert-type scale based questionnaire - online survey

Fessler et al (2005) SAMPLE

496 pregnant woman

Fessler et al (2005) PROCEDURE

• had to rate their level of disgust in 8 areas

  • contact with animals, body products, sex, personal space, death, hygiene, & food

  • presence of morning sickness was controlled w/ the first question which asked for their current level of nausea

Fessler et al (2005) RESULTS

disgust was higher in first trimester - may be correlated with the nausea & morning sickness that occurs first trimester

• even when controlling for nausea

Fessler et al (2005) FINDINGS

• disgust indicates evolutionary fitness

• disgust appears to protect the fetus

• natural selection favours the disgust response

neurotransmitters

bran chemicals that help communicate info via electrical impulses throughout the body - work closely with neurons

neurons: nerve cells

• receive signals, integrate hem, and communicate them to target cells

• mainly consist of dendrites, which process & receive the signals

• action potential (electrical signal) goes through the axon terminal & releases neurotransmitters from the PRESYNAPTIC

  • inhibitory - prevent the message from traveling (hyperpolarizes)

  • excitatory - make neurons pass the message (depolarizes)

• POSTSYNAPTIC receives from receptor sites on the membrane

  • agonist binds to the receptor site and increase the effect

  • antagonist bind to the receptor site and decrease the effect

Antonava et al (2011) AIM

determine how blocking ACh (acetylcholine) receptors with scopolamine (antagonist) impacts spacial memory

Antonava et al (2011) SAMPLE

20 healthy adult males

Antonava et al (2011) METHOD

true experiment

• injected with scopolamine or placebo 90 minutes before

double blind

Antonava et al (2011) PROCEDURE

• put in an fMRI while playing the game

• virtual reality where participants explored an area to find a pole

• after finding they were given a black screen for 30 seconds & were told to actively recall where to find the pole

• were then given a new starting point & used spacial memory to find the pole

• brain activity measured 6 times

• returned 3-4 weeks & redid test with the opposite treatment

Antonava et al (2011) RESULTS

• scopolamine - reduced activation of hippocampus (memory, learning & emotion)

• suggests that scopolamine ipairs memory or new info by decreasing spiking activity in hippocampus

• ACh may play a role in encoding spatial memories as there are high levels in the hippocampus

pheromone

a chemical substance produced & released by an animal

• affect the behaviour or physiology of others of its own species

• signaling pheromones produce rapid behavioural effects in animals that leads to mating

• secreted by glands but not into the bloodstream

have not been confirmed in humans BUT Androstadienone (AND)

• male steroid found in sweat/semen, linked to positive moods in females & is found to act like a pheromone

Zhou et al (2014) AIM

to see if AND influences human sexual behaviour

Zhou et al (2014) METHOD

true experiment

• IV - type of pheromone (AND) & gender & sexuality

• DV - response of the participant

Zhou et al (2014) SAMPLE

24 heterosexual & homosexual males

24 heterosexual & homosexual/bisexual females

Zhou et al (2014) PROCEDURE

watched a stick figure walk across a screen & needed to guess if it was male or female

were exposed to cloves (control) or AND or both

Zhou et al (2014) RESULTS

when hetero females & gay men were exposed to AND, they were more likely to say it was a man

AND had no sig impact on the hetero men or gay women

gene

genes - basic unit of heredity that store genetic info & are passed from parents to the future generations

located on chromosomes - contain hundreds of thousands of genes

made of dna - carry genetic instructions to allow for protein productions

genome is entire set of DNA

genotype is the genetic makeup

phenotype is the observable & physical expression

allele - different varieties of genes

• each has two alleles (mom and dad)

• can vary in genetic makeup and sequence

• longer allele is more protein - loss of function

epigenetics - study of how environment changes gene expression

• histones wrapping around chromosomes that hold the genes, preventing them from being transcribed

5-HTT gene (serotonin transporter) connected to the reuptake of serotonin in the synapses

• linked to MDD

serotonin (neurotransmitter) influences sleep, emotion & arousal

• synapse - gap between neurons where communication happens

Caspi et al (2003) AIM

investigate if a functional change in 5-htt will increase or decrease depression symptoms

Caspi et al (2003) SAMPLE & METHOD

opportunity sample of 847 participants aged 26 taking part in another study

natural experiment

Caspi et al (2003) PROCEDURE

separated into three groups

• 2 short alleles

• 2 l0ong alleles

• 1 short 1 long allele

interviewed about stressful life events more recently and childhood trauma

assessed correlation between stressful events and depression, length of allele and depression, & stress and length of allele

Caspi et al (2003) RESULTS

2 shorter had more depression symptoms

childhood maltreatment was predictive of MDD in groups with at least one short allele

2 long allele had less symptoms of depression

genetic similarity

• Genetic similarity refers to the degree to which individuals share genetic material

• Genes are the basic units of heredity and carry the instructions for the functioning and growth of all organisms

• One way psychologists study this is through twin and kinship studies, which help distinguish between the effects of genetics and the environment

• Monozygotic (MZ) twins share 100% of their genes, while dizygotic (DZ) twins share around 50%

  • Monozygotic twins come from one fertilized egg

  • Dizygotic twins come from two fertilized eggs

• If monozygotic twins show a higher similarity in behaviour than dizygotic twins, it suggests a genetic basis

• Concordance rate: probability that the same trait will be present in both members of a pair of twins

  • Explored by studying the twins separated or together to associate their behaviour

• Kinship studies extend this by comparing behaviours across relatives of different genetic relatedness

Weissman et al (2005) AIM

to study the potential genetic nature of Major Depressive Disorder (MDD)

Weissman et al (2005) METHOD & SAMPLE

longitudinal family study over 20 years - researcher triangulation

161 grandchildren & their parents & grandparents

looking at families at high & low risk of depression

original sample of depressed & not depressed patients was selected from an outpatient clinic

Weissman et al (2005) PROCEDURE

data was collected from clinicians who were blind to past diagnoses of depression or to previous interview data

original sample of parents & children were interviewed 4 times

children were now adults & had their own children

these people were evaluated by 2 experienced clinicians - one child psychiatrist & the other a psychologist

Weissman et al (2005) RESULTS

inter-rate reliability

• .82 for MDD

• .65 for anxiety

• .94 for alcohol dependence

high rates of psychiatric disorders in grandchildren with 2 generations of MDD

by 12 years old, 59.2% of grandchildren showed signs of a disorder

severity of parents MDD meant higher rates in children

if parents were depressed but not grandparents, no significant impact on children