Acknowledgements
The content acknowledged below is Proprietary (see terms and conditions) and is used under licence.Course image: NIH Image Gallery in Flickr made available under Creative Commons...
View ArticleReferences
Blakemore, C. and Cooper, A. (1970) Development of the brain depends on visual environment, Nature, 228, pp. 477–8.Caspi, A., McClay, J., Moffitt, T. E., Mill, J., Martin, J., Craig, I. W., Taylor, A....
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View ArticleEnd of course questions
Question 1Explain your reasons for agreeing or disagreeing with each of the following sentences.(a) If a disease has a genetic basis and someone has the (abnormal) alleles for the disease, then that...
View Article10 Course summary
The course began by considering what factors contribute to individual differences. The case was made, with the spiders, and later with genetic diseases, that the genome was very important. Subsequent...
View Article9.4 Summary of Section 9
This section has illustrated what has to be done, by way of a long-term study, to yield meaningful information on the relationship between genes and development and the behaviour of the organism. It...
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9.3 Monoamine oxidase A, maltreatment during childhood and later violence
One Dutch family was found to have a history of antisocial (aggressive) behaviour. Genetic studies were conducted and a potential culprit gene MAOA, monoamine oxidase A, identified. The aggressive...
View Article9.2 Antisocial behaviour disease
The psychological arena is hugely complex because there are additional issues of responsibility and treatment. Briefly, society takes a more lenient attitude towards the behaviour of someone who is ill...
View Article9.1 The psychological arena
The examples in the previous section followed the traditional medical approach, namely that there is a disease, it can be diagnosed (identified), and the cause of the disease, be it viruses, bacteria,...
View Article8.5 Summary of Section 8
Genes do influence development. However, genes do not always determine the developmental path. The prognosis for Wilson's disease is very good, because environmental intervention is possible. The...
View Article8.4 Fragile X syndrome
Fragile X syndrome is the final example of a genetic disease considered here.Activity 21What does the term ‘genetic disease’ mean? AnswerGenetic disease means that the symptoms of the disease are...
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8.3 Lissencephaly
Lissencephaly, literally meaning ‘smooth brain’, is characterised by the absence of sulci and gyri, and by a four-layered cortex, instead of the usual six layers, with the majority of cortical neurons...
View Article8.2 Wilson's disease
The effects of a protein that is absent, or present but not doing its job, may not be evident for many years. This is called late onset, and is exemplified by Wilson's disease. Many molecules within...
View Article8.1 Genes and behaviour
In the preceding sections many different proteins have been mentioned. These proteins are the receptors, signals, channels, enzymes, transporters, structural components and transcription factors that...
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7.8 Summary of Section 7
This section has sought to illustrate the formation of connections between neurons and their targets by exploring a few examples. The picture that emerges is one of cells at different stages of...
View Article7.7 Neurogenesis
Brains contain within them the seeds of their own salvation and the seeds of their own destruction. In its early stages, the brain produces vast numbers of neuroblasts as stem cells divide at a huge...
View Article7.6 Synaptogenesis
The formation of synaptic connections is an essential property of nervous system development. Synapses are formed between neurons and also with targets that are not part of the nervous system, e.g....
View Article7.5 What do neurotrophins do?
Neurotrophins shut down the mechanism of apoptosis. Neurotrophins do this by attaching to receptors in the cell membrane of the innervating axon and activating a cascade of biochemical reactions. The...
View Article7.4 Elixirs of the nervous system: neurotrophins
According to Section 7.2 axons obtain an elixir from targets at their synapses.Confirmation that there is indeed an elixir came from a series of events that reveals how much of science really works....
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7.3 Selected to die: studies of the CNS
Recent evidence has revealed that during development in mice, cell death occurs in two phases. The first phase is at about E15–E17 days, during neuron proliferation, and will not be considered further...
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7.2 Selected to survive: studies of the PNS
Viktor Hamburger carried out a series of classic embryologieal experiments over a period of about 30 years. He investigated the relationship between the size of target tissue in chick embryos and the...
View Article7.1 Neuron proliferation
There is a huge proliferation of neurons in early life. Even whilst that proliferation continues, some cells, e.g. neuroblasts, stop being able to divide. At some later stage the proliferation itself...
View Article6.5 Summary of Section 6
Growth cones respond to proximal and distal cues. The proximal cues in the extracellular matrix or other cells affect adhesion and result in chemotactic guidance. Distal cues are also in the...
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6.4 Crossing the midline: a case study
Many neurons on the left side of the body make contact with targets on the right, contralateral, side of the body, and vice verse. Crossing the midline is particularly prevalent in descending neurons...
View Article6.3 Directing the growth cone
The growth of the growth cone has been likened to the progress of a climber. The climber can only go where there are satisfactory hand and foot-holds and where progress is not blocked by physical...
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6.2 The growing axon: growth cones
The growth cone is a small area of active tissue at the tip of a growing axon (Figure 15). As the growth cone moves forward, it adds new material to the cell membrane and so extends the axon. (New...
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6.1 The intricacies of neuron growth
Particular nerves, such as those sensory nerves that arise from the nasal retina (the side of the retina adjacent to the nose), cross the midline; other sensory nerves, such as those that arise from...
View Article5.5 Summary of Section 5
When oestradiol combines with its receptor inside neurons, the cell produces proteins which protect it from cell death. As a consequence, the male brain, which has oestradiol in its neurons in early...
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5.4 Retinoic acid
The retinoic acid story is both distressing and illuminating. It is distressing because with hindsight it is possible to see how the suffering of many people could have been averted. It is illuminating...
View Article5.3 Transcription factors
At various places in this course, reference is made to new proteins being made, or to genes being switched on. The control of gene transcription is a hugely complex area and well beyond the scope of...
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5.2 Sexually dimorphic nucleus of the preoptic area (SDN-POA)
As well as affecting behaviour (Section 3.4) neonatal testosterone also affects the physical characteristics of some areas of the brain. One of these is a small area of the hypothalamus, the medial...
View Article5.1 The nervous system
Development has so far mostly been assessed in terms of the gross performance, the overt behaviour, of the organism. Relationships have been established between certain environmental events and certain...
View Article4.4 Summary of Section 4
Two important points emerge from this section. The first is the powerful effect of maternal contact on the development and later behaviour of their charges. In the Feldman study the disadvantages of...
View Article4.3 Small babies: the sequel
Evidence that some of the consequences of being born prematurely were enduring was discussed in Section 3.2. However, what emerges from Section 4.2 is that the quality of maternal care can alter the...
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4.2 Licking/grooming-arched back nursing
Rat mothers perform a number behaviours towards their pups: they build a nest for their pups, keep them in it and occasionally lick them and nurse them. (Rat fathers have a parental role too but it is...
View Article4.1 Parental behaviour
A moment's reflection will convince you that parental behaviour differs from one family to another. The effect that different parental styles have on the development of the recipient offspring is very...
View Article3.5 Summary of Section 3
The developing organism is nudged onto different developmental paths by the environment in which it finds itself. Thus the experience of being premature, or of experiencing only horizontal visual...
View Article3.4 Sensitive periods
The steroid hormone testosterone plays a major role in the development of mammals. In particular it is instrumental in causing differences between males and females. One well explored difference...
View Article3.3 Plasticity and permanency
The visual system relies on, amongst other things, the exquisitely precise connections between the retina, the lateral geniculate nucleus of the thalamus and the visual cortex. In precocial organisms,...
View Article3.2 Small babies
Development continues in the womb until birth, which, in humans, is about 38 weeks after conception. (The often quoted duration of pregnancy of 40 weeks is based on pregnancy beginning on the first day...
View Article3.1 Introduction
We each begin life with a unique genome. As we grow and develop, we are each subjected to a range of factors that influence the way development proceeds. Most of those factors are common to us all, the...
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2 Growth and development: the big picture
The scale of the problem facing the human zygote is vast. The zygote, the single cell resulting from the fusion of a sperm and an ovum, is about the size of a full stop on a nomal printed page, yet...
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1.2 The ‘genes and behaviour’ problem
Amidst the progressive change to the brain and nervous system that occurs during development, there is one constant, one fixed element; the set of deoxyribonucleic acid, DNA, molecules found in each...
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1.1 Introduction
This course addresses the question of how the differences between individuals, especially in behaviour, arise during development. Development, the transformation of the single cell, the zygote, into an...
View ArticleLearning outcomes
After studying this course, you should be able to:recognise definitions and applications of each of the terms printed in the textcritically evaluate statements about the influence of the genome on...
View ArticleIntroduction
This free course examines issue of nature and nurture, how genes and the environment interact in the development of the nervous system to make each of us unique. In particular it looks at the period...
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