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BIO114 The Making of Individual Differences-OPEN University
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Open University
SD226_1 12 Hours
Intermediate
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Course Description
This unit 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
from conception to birth. It is a topic that should be of wide
interest to students.
After studying this unit you
should be able to:
- recognise definitions and
applications of each of the terms printed in bold in the text;
- critically evaluate statements about the influence of
the genome on behaviour;
- explain the ways in
which genetic and environmental factors influence the development of the
nervous system;
- provide examples of the
influence of genetic and environmental factors on the development of the
nervous system and behaviour;
- discuss possible
flaws and short comings in experiments designed to examine the roles of
genes and environment in the development of behaviour;
- explain why different genetic diseases have different
outcomes;
- recognise the significance of
experiments similar to those described;
- explain
the role and control of transcription factors;
- recognise
the importance and discuss some aspects of the control of axon growth.
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Introduction
 Introduction
Resource- This unit 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 from conception...
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1 Individual differences
- 1.1 Introduction Resource
- This unit 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 adult...
- 1.2 The ‘genes and behaviour’
problem Resource
- 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 cell....
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2 Growth and development: the big picture
- 2 Growth and development: the big
picture Resource
- 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 within...
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3 The unique phenotype
- 3.1 Introduction Resource
- 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...
- 3.2 Small babies Resource
- 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...
- 3.3 Plasticity and permanency Resource
- 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,...
- 3.4 Sensitive periods Resource
- 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 concerns...
- 3.5 Summary of Section 3 Resource
- 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 stimuli,...
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4 Confounded variables: sensitive skin
- 4.1 Parental behaviour Resource
- 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...
- 4.2 Licking/grooming-arched back
nursing Resource
- 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...
- 4.3 Small babies: the sequel Resource
- 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 course...
- 4.4 Summary of Section 4 Resource
- 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 prematurity...
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5 Mechanisms
- 5.1 The nervous system Resource
- 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...
- 5.2 Sexually dimorphic nucleus of
the preoptic area (SDN-POA) Resource
- 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 preoptic...
- 5.3 Transcription factors Resource
- At various places in this unit,
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 this...
- 5.4 Retinoic acid Resource
- 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...
- 5.5 Summary of Section 5 Resource
- 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 life,...
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6 Axon guidance
- 6.1 The intricacies of neuron
growth Resource
- 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 the...
- 6.2 The growing axon: growth cones Resource
- 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 axonal...
- 6.3 Directing the growth cone Resource
- 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 obstacles...
- 6.4 Crossing the midline: a case
study Resource
- 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 (e.g....
- 6.5 Summary of Section 6 Resource
- 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 extracellular...
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7 Survival and death
- 7.1 Neuron proliferation Resource
- 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 virtually...
- 7.2 Selected to survive: studies of
the PNS Resource
- 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 size...
- 7.3 Selected to die: studies of the
CNS Resource
- 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...
- 7.4 Elixirs of the nervous system:
neurotrophins Resource
- According to Section 7.2 axons
obtain an elixir from targets at their synapses.
- 7.5 What do neurotrophins do? Resource
- 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 sequence...
- 7.6 Synaptogenesis Resource
- 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. muscle....
- 7.7 Neurogenesis Resource
- 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 rate,...
- 7.8 Summary of Section 7 Resource
- 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 development...
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8 Genes become you
- 8.1 Genes and behaviour Resource
- 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 enable...
- 8.2 Wilson's disease Resource
- 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 the...
- 8.3 Lissencephaly Resource
- 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...
- 8.4 Fragile X syndrome Resource
- Fragile X syndrome is the final
example of a genetic disease considered here.
- 8.5 Summary of Section 8 Resource
- 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 prognosis...
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9 Genes and their influence on behaviour
revisited
- 9.1 The psychological arena Resource
- 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,...
- 9.2 Antisocial behaviour disease Resource
- 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...
- 9.3 Monoamine oxidase A,
maltreatment during childhood and later violence
Resource
- 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 individuals...
- 9.4 Summary of Section 9 Resource
- 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 also...
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10 Unit summary
- 10 Unit summary Resource
- The unit 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 sections...
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End of unit questions
- End of unit questions Resource
- Explain your reasons for agreeing
or disagreeing with each of the following sentences.
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References and Acknowledgements
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Copyright 2007,
by the Contributing Authors.
Cite/attribute Resource.
administrator. (2010, January 30). BIO114 The Making of Individual Differences-OPEN University. Retrieved March 11, 2010, from Free University Courses OCW Courses OpenCourseWare Freeversity Foundation Web site: http://freeversity.org/science-and-mathematics/biology/bio114-the-making-of-individual-differences-open-university.
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