PSYC1101 - Gene & Behaviour

behavioural genetics

the study of how genes and environment interact with each other to influence psychological traits

how do people study heritability?

• family studies

• adoption studies

• twin studies

heritability

• how differences in a trait across people are influenced by genes vs environment

• 100% heritability = 0 environmental influence

family studies

• the degree to which a trait “runs in the family”

• if a trait comes from your genes, your family members should be more similar in that trait

adoption studies

• adopted parents → 0% shared genes

• the differences between a trait thats common with biological vs adopted parents

limitation of adoption studies

• selective placement (adoption centres are selective in choosing parents - parent's traits may be related)

• children are not always adopted at birth (could share lived experiences w/ biological parents when younger)

limitation of family studies

• it is difficult to separate whether the trait is due to shared genes or sharing the same environment

misconceptions about behavioural genetics

1. heritability tells us if a trait can be changed by different environmental pressures

2. heritability tells whether a gene causes a trait or not

the warrior gene

• variant of the MAOA gene that has been linked with impulsivity, aggression and criminal behaviour

• ued to support racial stereotypes involving aggressive behaviour

the infidelity gene

• variant of the dopamine receptor (DRD4) gene that has been linked with cheating

the iq gene

• apparently a US company found a way to screen embryos for the IQ gene (claims that genes is linked with being smart)

Genetic Determinism

• the idea that genes completely determine behaviour

• is wrong because:

• - ignores environmental factors

• - oversimplifies complex traits (multiple genes can contribute to behavioural differences)

corpus callosum

• allows two lobes to communicate with each other

• right = language

• left = tone/emotion

frontal lobe

high order thinking, motor control, emotional regulation, language production

parietal lobe

processing of senses, spatial awareness

occipital lobe

visual processing, facial & object recognition

temporal lobe

memory, hearing, language comprehension

cytoarchitectonics

• road map of brain based on differences in structure of stained tissues

• 52 areas - each area has a different function

area 17

primary visual cortex

neurons

• processes information & sends nerve impulses

glial cells

• protect against diseases; keeps brain healthy

• provide structural support

• produces myelin

prefrontal cortex

executive functions (planning, inhibition, working memory)

primary motor cortex

planning / preparation movements

pre-motor cortex

selection of physical movements to accomplish plan

supplementary motor cortex

coordination of movements, including hands

somatosensory association area

processing of senses in the brain

centre vision cortex

high detailed

peripheral vision cortex

less detailed; sensitive to motion

auditory cortex

processing of auditory information

prosody

processes emotional tone in speech

allows us to detect sarcasm

reticular formation

• a network of neurons part of both hindbrain & forebrain

• controls arousal & sleeping / waking cycle

hypothalamus

• controls basic survival & homeostatic actions

thalamus

• gateway between sensory input and other cortexes

hippocampus

• transfer from STM to LTM

cerebellum

• complex motor movements

• balance

• muscle tone / posture

• stores procedural memories

medulla, pons

• breathing

• basic autonomic functions

depolarisation

• occurs at -55 mv

• membrane becomes permeable to sodium ions

neurotransmitters

• chemicals that allow neurons to communicate across synapses