Humans have the largest brain of all primates and the longest period of brain development
From birth to teenage years, there is a fourfold increase in the volume of the human brain
Humans are the only species to show differential development in timing across cortical brain areas
At birth, the child’s brain consists of 100 billion neurons, organized into groups that perform particular functions like interpreting sounds, storing memories, and learning new skills
Brain growth begins in utero at 18 days after fertilization
During the prenatal period, brain development consists of three stages: Geminal (Fertilization – 2 weeks), Embryonic (2 – 8 weeks), and Fetal (8 weeks – birth)
During the Geminal Stage, the fertilized egg attaches itself to the uterus wall and undergoes rapid and methodical cell division
The Embryonic Stage involves the development of major organs and basic anatomy, with the fetus having three layers: Ectoderm, Mesoderm, and Endoderm
During the Fetal Stage, rapid changes in development occur, including the development of physical characteristics, organs, and bodily systems
The brainstem (hindbrain) and midbrain are the first areas to develop, governing autonomic functions necessary for life and reflexes
Post-natal brain development involves fine-tuning the brain's circuitry through processes like synaptogenesis, synaptic pruning, programmed cell death, and myelinization
The brain continues to refine and develop connections through dynamic and adaptive processes influenced by genetic expression, Epigenetics, social learning, and experience
An enriched environment causes cortical neurons to thicken, sensory experiences trigger electrical activity that strengthens connections, and the cortex prunes itself into the most efficient structure around 3 months
Beyond infancy, the limbic system regulates emotions, the frontal lobes support advanced cognitive functioning, and the pre-frontal cortex continues to grow until the early 20s
Brain growth occurs in fits and spurts, coinciding with changes in cognitive behavior, and the timing of events in brain development is crucial
The prenatal brain is sensitive to negative influences like alcohol and malnutrition, as well as positive influences like enrichment
Teratogens are substances that exert adverse influences on development, such as drugs, smoking, disease, radiation, and maternal stress
Fetal Alcohol Syndrome (FAS) can lead to physical defects, growth retardation, central nervous system impairments, and permanent effects
Moderate drinking and binge drinking during pregnancy increase the risk of FAS (fetal alcohol syndrome), and even small amounts of alcohol can impact fetal development
Neglect during early experiences can alter brain growth and organization, leading to long-term impacts on emotional processing, social relationships, and IQ
The extent of environmental impact can determine the severity of atypical brain development
Neuroimaging of 122 neglected children showed altered brain growth
Some neglected children were raised in cages in dark rooms for the first years of their lives
Frontal Occipital Circumference, brain growth, and organization were worse in neglected children compared to normal children
Mainly affected the globally neglected children
Global neglect likely caused by lack of sensory experiences (sound, smell, touch) and poor nutrition
Brain structure is genetically determined, but brain plasticity means stimulation received also crucial for development
FAS symptoms are most severe when the "dose" of alcohol is highest
Moderate drinking (1-3 oz per day) can lead to serious (though less pronounced) symptoms of FAE
FAE/FAS risks are greatest following periods of binge drinking
Even drinking less than 1 oz of alcohol per day increases the likelihood of the fetus developing FAS
Physical defects associated with Fetal Alcohol Syndrome (FAS) include:
Flattened midface
Thin upper lip
Indistinct/absent philtrum
Short eye slits
Growth retardation in FAS can result in:
Lower birth weight
Height and/or weight low
Central Nervous System effects of FAS include:
Impaired fine motor skills
Learning disabilities
Behavioural disorders
Mental handicap (found in approx 50% of those with FAS)
Alcohol drunk by the mother reaches the placenta quickly, making it more dangerous than all drugs (including cocaine), leading to low birth weight, birth defects (FAS), miscarriage, etc.
Effects of FAS are permanent and cannot be outgrown
Children born with FWS can present with:
Nasal hypoplasia (stunted growth of the septum and nasal bridge)
Chondroplasia (bone calcifications)
FWS typically presents in only 1/3 of mothers who take warfarin, and only when taken within the first trimester
Cognitive impairments are associated with FWS, but by age 10/11 the majority of FWS children show no difference to matched controls with no exposure
Teratogens are substances that exert an adverse influence on development