Prenatal Development

conception/ fertilisation (fusion of sperm and egg) / zygote (fertilised egg)

1. cell division / 2. cell migration / 3. cell differentiation/ 4. cell death

mitosis- results in proliferation of cells

movement of cells from point of origin in other locations in embryo

transformation of stem cells into roughly 350 different types of specialised cells

selective death of certain cells

germinal period - conception to implantation / rapid cell division / cell differentiation

embryonic stage - from implantation to 8th week / inner cells mass becomes the embryo and the rest of the cells develop into its support systems

the placenta - exchange of materials in the bloodstream - in: nutrients, oxygen - out: c02, waste

foetal period - 9th week -until birth / continued development of physical structures and rapid growth of body / increasing levels of behviour and sensory experince learning

- U shaped groove becomes a tube
- Differentiates into brain and spinal cord
- Importance of folic acid
- During early development 250,000 neurons are produced per minute

- Emergence of some structural features
- Folded cortex emerges from having lots of neurons
- Patterns of gyri/sulci pulled into shape by tension of axon bundles (white matter tracts)

teratogens- - Environmental agents that have caused harm during prenatal development
- E.g. Minamata disease - caused by mercury poisoning (eating fish) - in pregnant parents, mercury is removed from the body and concentrated in the fetus
- Caused major disruptions to limb development
timing: - Sensitive periods: organs are most vulnerable during he formation of basic structures - timing differs for different systems e.g. thalidomide 4th and 6th week
individual differences e.g. genetic susceptibilty

- Nature= genetic blueprint (things we are born with)
nurture= role of experiences

each connection in the brain is specified by our genes

- Hebbian learning 'cells that fire together, wire together'
- Spontaneous electrical activity enables networks to form before sensory experience shapes the system further
- Spontaneous activity from the retina, and cochlea helps to form the visual and auditory pathways
- Spontaneous activity in developing spinal and motor circuits contributes

- Link between structure and experience
- Plasticity - capability of reorganisation, brain areas can acquire new functions
Limits of plasticity:
- Previously formed connection wont fully b overwritten

· Pre natal ultrasound
· Prenatal MRI
· Prenatal EEG
· Prenatal MEG
· Modified MEG - optically pumped magnetometers
Behavioural methods - movements, heart rate changes

- Spontaneous movements from around 5 weeks - hiccups, swallowing, foetal breathing at 10 weeks
- By 12 weeks most of the movements present at birth have appeared - jerky movements become integrated

- Parent heartbeat, blood flow, breathing
- 28 weeks + sounds from the environment
Evidence:
- Heart rate changes when the pregnant person starts speaking
- More head turns towards the pregnant parents voice played on the speaker
- Able to distinguish between music and speech = importance of auditory exprinces in brain development

- Amniotic fluid takes on odours from what the parent has eaten- taste and smell
- Taste - preference for sweeter tastes (sugar injected into amniotic fluid - infants ingested more)
- Parent ingested carrot or kale - facial expression and movement investigated with ultrasound