The case study of Genie is well-known throughout psychology. The case begins with Genie's parents. Her mother (Irene) banged her head as a child, was blind in one eye and was 90% blind in the other eye. Genie's father (Clark) was twenty years older than her mother and was described as being 'overprotective'.
Genie's father did not want children, two of his children with Irene died at early ages and a third child was looked after by the paternal grandmother. Yet, in 1957 Genie was born.
Shortly after Genie's birth, her grandmother died in a hit-and-run. This incident left Clark feeling very depressed and outraged. He grew isolated and deemed society to be 'evil'.
When Genie was discovered, she had spent all thirteen years of her life in a tiny bedroom. She had mainly been restrained on a potty, but also with a sleeping bag acting like a straight-jacket. All her life, Genie had been actively discouraged from making any sounds at all. When in contact with her, Genie's father merely growled. Alongside this, Genie's mother and brother only spoke in whispers for fear of the father - therefore Genie heard next-to-nothing in her first thirteen years of life.
Genie's visual stimuli was also limited as her bedroom contained two small windows which had been taped up. The only thing she had been allowed to occasionally play with was a plastic raincoat. When it came to food, Genie was fed either baby food or a hard-boiled egg in complete silence and if she choked or spat any out, it would be rubbed in her face. Apparently, her father had said that she would not live beyond twelve years old, and that if she did, only then could her mother seek help.
Genie was discovered and taken into care in 1970. Her father committed suicide on the day he was due in court for abuse charges. When she was found, Genie weighed only 59lbs and was 4' 5" tall. She was incontinent, unable to chew solid food and couldn't swallow properly. If Genie got excited she she would urinate and she was unable to focus her eyes beyond 12ft. Due to the conditions she had been kept in, Genie was unable to extend her limbs properly which made walking difficult. The lack of speech and noise that she had experienced, meant that she knew very few words.
When she was first taken into care, some progress was made. For example: she was toilet trained within three days. She also began to hoard plastic objects and held people's hands to stop them from leaving. Unfortunately, years later Genie still had no reaction to warmth/cold, was easily terrified, was still unable to chew food and was still limited to just a few words of vocabulary.
This unique case greatly emphasises the importance of experience in our development!
Neurodevelopment
There are two stages:
1) Nature - growth of the embryo
2) Nurture - experience of life
The photo above shows X and Y chromosomes. The X chromosome contains 1000 genes, whilst the Y chromosome contains 80 (the latter is due to 300 million years of chemical attack).
XX: makes a female
XY: makes a male
1-2% of men are infertile due to the malfunctioning of the Y chromosome. The Y chromosome also contains things which are harmful to women.
The Zygote
The male's sperm is X/Y while the female's egg is X only. In terms of sperm, X is hardier and Y is faster.
Mortality Rates
Males experience higher mortality rates at all stages of life (Dodson, 2007). When it comes to conception the mortality rates are: 100 girls/125 boys. At birth the rates are: 100 girls/105 boys - almost 20% don't make it.
Upon conception the zygote continually divides - by the 5th day there are 16 cells. Is this zygote simply an amorphous mass (shapeless mass of protoplasm)? No:
1) You can differentiate between cells e.g. muscles, glial cells, bones
2) Cells must be able to get to where they need to be, then align correctly
3) Can establish the relationships between them
The mesoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the endoderm (inside layer) and ectoderm (outside layer). The mesoderm relates to the circulatory system, gonads, muscle, bone and cartilage. The endoderm relates to the digestive organs and the lungs.
Names for zygote:
* Zygote at fertilisation (up to 2 weeks)
* Embryo (2 to 8 weeks)
* Foetus (9 weeks to birth)
Neural Plate
There neural plate develops three weeks after conception. This is the first stage of development in all vertebrates. The vertebrate brain includes the forebrain, midbrain and hindbrain. The next images show interesting stages in the development of a human embryo.
This next picture shows the development of the human face during weeks 10-14.
This diagram shows what the human embryo looks like at approximately 28 days. Note the presence of the forebrain, midbrain and hindbrain (the latter of which are the beginning of the brainstem).
Stem Cells
Stem cells are able to self-renew. They are also undifferentiated meaning that they can develop into anything. When in the nervous system, some become neurons but most become glial cells.
Migration
Once created, cells have to move to their correct location. There are two types: glia-mediated translocation (diagram) and somal translocation (chemical attraction).
Neural Proliferation
Neural proliferation is the massive expansion of cell numbers in the neural tube. Not all areas grow at the same rate, this is determined by species e.g. birds and fish have larger areas responsible for 3D.
What happens on arrival in the correct location?
Aggregation - thanks to certain chemicals, similar cells bind together.
Once neurons have migrated to the right place and have aggregated into structures, axons and dendrites grow out from them. Some neurons extend finger-like growth cones or filopodia.
The French Flag Model below shows the ZPA (Zone of Polarising Activity).
Synapse Formation
Once the axons are in the correct place, a network needs to be built. Most neurons are connected to at least a thousand others (the average is around 7,000). One neuron can build an axon, but two are needed to build a synapse. This is called synaptogenesis. Connections are made with the best available cells, this is shown in the diagram below.
The graph below shows synapse levels in postnatal development:
Alcohol readily passes into the placenta, disrupting synaptogenesis. It causes Foetal Alcohol Syndrome (FAS) which can lead to brain damage, deformity and poor coordination.
Infant Development
Between birth and adulthood, the brain quadruples in size. There are however, no additional neurons being developed. This brain growth is due to myelination, further branching out etc.
Linking back to Genie, early experience is vital as unactivated neurons will die (apoptosis).
According to Spear (2000), the brain only achieves maturity in late adolescence. After birth the focus of development is mainly on the pre-frontal cortex.
Myelination is required for adult function. Most myelination is done by 3-4 years.
So there you have it! Basic neurodevelopment!
xoxo
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