Stages of brain development Flashcards
Prenatal
First trimester, 16days after fertilisation the human embryo forms a neural tube ( what becomes brain and spinal cord ). Cells created around 6 weeks after gestation until 20 weeks gestation .These then migrate to correct location in brain where they become neurons and begins to form nervous system . Process of migration starts around 8 weeks and is completed by 29 weeks gestation.
When foetus around 2 months of gestation, neural tubes divides into brain cells and nerve cells and cerebral cortex formed ( Part of brain responsible for how we think and act ad memories and intelligence). It id divided into 4 different sections, frontal lobe, temporal lobe, the parietal lobe and occipital lobe.
4-6 months = 2nd trimester = brain fully develops although not grown to full size. At this point 100 billon neurons have mostly developed and around 20 weeks gestation , neurons start to develop including axon and dendrites.
5th month = simple synapses form allowing neurons to communicate with each other . End of 2 trimester , nervous system develops enough that the foetus can react to loud noises outside the womb.
3rd and final trimester - brain continued to grow. Brain development affected by what mother consumes. Example : foetus alcohol condition : alcohol disrupt nerve connection in baby’s brain -> learning difficulties when born
Childhood
After child born, brain develops many new neural connections . For example : in visual cortex number of synapses nearly doubles up to the age of 4 months
Ability to see clearly is limited, by the time its 5 months old the new synapses allow it to see in 3D and also ability to see in colour. Around 3 density of synapses in PFC is at its peak = allows child to use past memories to understand present and start to understand cause and effect During later childhood, these connections are pruned
Adolescence
The brain undergoes significant changes, grey matter which is found on the surface of the brain and composed of cell bodies of neurons, nerve fibres and supports cell has reached its max density.
Areas of the brain like the limbic system - regulates emotions and help form new memories - are first to mature. PFC - regulates decision making - last to mature Difference in time taken for limbi system and PFC to develop is thought to explain behaviour in adolescence (risks). The Fl continues to develop and reach maturity by age 16.
Adulthood
At age 25, the rational part of the brain the PFC fully develops. This is the part of the body needed to make rational decisions and focus on long term consequences of actions = reduces impulsiveness
During later adulthood, people can develop neurodegeneration disorders such as Alzheimer’s or Parkinson’s disease. Neurodegeneration disease get progressively worse over time and leads to death of neurons in brain. In Alzheimer’s disease, scientists believe that changes in cortex result in problems in thinking and memory
