Introduction
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...
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...
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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...
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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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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...
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...
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 Article3.3 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 Article3.4 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 Article3.5 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 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...
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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 Article4.3 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...
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 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...
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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 Article5.3 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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5.4 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 Article5.5 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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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...
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