Back to Revision NotesQ1.
Bk. 2 Ch 4; Bk. 4 Ch 5
Similarities: general structure (cleft, apposition zones); general functioning
(vesicles, diffusion, receptors, IPSP/EPSP); general modulation (breakdown
and/or re-uptake of neurotransmitter, neuromodulation), mode of action
(response to AP, calcium influx)
Differences: type of neurotransmitter(s), type of receptor(s), length
of apposition zone, location of synapse in relation to axon hillock, and
cell body/dendritic spine, nature of neuromodulators, number of vesicles,
number of receptors
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
Number of eggs is a measure of partial fitness. What really matters is the survival and laying patterns of the chicks. If the 12 all survive and the females lay a normal sized clutch of eggs, then Ann's fitness certainly isn't low. To get a clear picture of Ann's fitness it is necessary to know what all Ann's offspring, and their offspring, do. This would approach a measure of absolute fitness. Furthermore it is necessary to know what other female great tits in the population are doing, by way of rearing offspring/grand offspring. The ethologist would have to accumulate data from several families, including Ann's over many years to establish Ann's fitness relative to the rest of the population.
Structure: 4 marks
Content:
Ann's fitness up to 6 marks
study of fitness up to
6 marks
Understanding: 4 marks
Gene issues - Pleiotropy (one gene can have many effects e.g. PKU),
polygeny (many genes influence a character e.g. movement), phenocopy (appearance
of symptoms without the gene), biological (excludes social and psychological),
reductionist (finding the gene solves the problem).
Schizophrenia issues - diagnosis (psychosis, symptoms), causes (social,
psychological, biological), treatment (some drugs are effective) heritable
(twin studies).
There are two separate issues which need to be discussed: the first
is the nature of schizophrenia, and the second is what it means to have
a gene "for" something. I shall deal with each of these issues in the following
essay.
Schizophrenia is a psychosis in which the individual fails to respond
to normal stimuli in an appropriate way and often complains of stimuli
(e.g. voice, or images) which others present are not aware of. It is difficult
to diagnose because the symptoms are so diverse and also because their
presence is erratic. Indeed some authorities recognise the schizophrenias
rather than just one. The difficulty of diagnosis is compounded by a difficulty
of treatment, stemming in part from conflicting views on the causes, ranging
from the social, the psychological and the biological. Briefly, the social
has regard to the family and circumstances in which the individual lives;
the psychological has regard to the circumstances under which the individual
has grown up i.e. their parents and siblings; and the biological has regard
to the brain anatomy and biochemistry of the individual, the ventricles
being larger in schizophrenics and the metabolism of dopamine being unusual.
It is difficult to imagine how one gene, which after all only codes for
one protein, could give rise to such a wide range of symptoms. On the other
hand the symptoms of PKU are varied and that is caused by one gene.
A gene for schizophrenia would place the cause of schizophrenia firmly
in the biological camp, would render it heritable and, possibly, untreatable.
It would also be a victory for the reductionist view and detract from the
social and psychological perspectives which, nevertheless, would still
have a lot to offer in terms of helping the schizophrenic make sense of
and live in society.
The gene issues are also necessarily biological and reductionist. A
gene may well be associated with a particular illness e.g. PKU, but that
does not mean the individual has to suffer with the disease, it can be
treated. Nor does it mean that the gene necessarily causes the disease
- it depends on the other circumstances of the individual, not least of
which is the other genes in the genotype. A gene does not produce a condition
as complex as schizophrenia; other genes must be involved - schizophrenia
is polygenic. Furthermore it may well be the case that someone with the
symptoms of schizophrenia may not have the gene at all. This is phenocopy.
The principle issue then is that such a search is reductionist and biological
and an apparent resolution to the schizophrenia problem, but is not necessarily
a solution.
Structure: 4 marks
Content: max. 12 marks
schizophenia up to 10
genetics up to 10
Understanding: 4 marks
Central: PAG, raphe, descending pathways, T cells, opioids, naloxone,
surgery (ascending pathways).
Gate: substance P, c fibre and Aδ fibre interaction at T
cells, spinal cord
Peripheral: prostaglandins, bradykinins, nociceptors, c fibres, analgesics(
e.g. aspirin), local anaesthetics, substantia gelatinosa, TENS
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
There are moral and ethical reasons: brain surgery is likely to be permanent
and the outcome not completely predictable; who decides whether the surgery
should occur, and under what circumstances?
There are biological reasons: there is not an aggression centre. Studies
of Adam's and Flynn have shown that different areas of the hypothalamus
can influence aggression but so too do the amygdala and septum. The hypothalamus
is involved in other aspects of behaviour. The brain is also highly complex
and so removing one area may damage another or the pathways to and from
another. Aggression uses the same sensory and motor apparatus as other
behaviours which makes the likelihood of altering other behaviours considerable.
How has aggression been defined and diagnosed?
Some aggression (competition) is a necessary part of life.
What are the long-term effects?
Structure: 4 marks
Content: max. 12 marks
aggression up to 6
lesioning up
to 6
issues up to 4
Understanding: 4 marks
Testosterone is a key determinant of sex and behaviour in humans. Altering the balance of that hormone in early life could override the child's natural sex in terms of anatomy, physiology and behaviour. The effects of excess testosterone have been clearly demonstrated in female rats and monkeys. The genitalia could become male-like. The physiology could be altered to inhibit the oestrus cycle - the organising effect of testosterone is permanent. Brain anatomy and function could be altered. For example such treatment renders the pre-optic nucleus and the amygdala be male-like, the latter correlating well with rough and tumble play. Genetic females would be masculinized. The effect of additional testosterone on male babies is unknown but it is likely to alter the "natural" behaviour of the infant for precisely the same reasons as the females.
Structure: 4 marks
Content: 12 marks
anatomy up to 4
brain, physiol. up to 4
behaviour up to 4
Understanding: 4 marks
Q7.
Bk. 1 Ch 2 & 5; Bk. 3 Ch 2
Innate behaviour could be considered as genetically determined (and
hence unaffected by environmental factors) or as accurate on first appearance.
Favourite topic of early ethologists who considered the former definition.
e.g. Paralaster, egg rolling, gull chick pecking.
Evident now that most behaviours subject to modification with practice,
hence latter; definition preferred e.g. gull chick pecking, acoustic imprinting,
song learning. The label does not explain the behaviour.
At one end of the nature/nurture debate.
Better students will ponder whether communication in the green tree
frog is innate.
Structure: 4 marks
Content: 10 marks
Understanding: 6 marks
Definition of receptive field with examples from vision and touch (possibly
also pain and sound - tonotopic maps). Differences between receptive fields
in size and sensitivity.
The importance of lateral inhibition and convergence - receptors can
be part of several receptive fields of "higher" neurons.
Structure: 4 marks
Content: 12 marks
Understanding: 4 marks
Does the mind emerge from the properties of large quantities of neurons
(i.e. epiphenomenalism) or does it have a separate existence (dualism)?
If it emerges, what sort of animals have a mind or is it peculiarly human?
Is it simply a different way of describing the same thing (i.e. identity
theory).
How is mind defined? As cognition, as consciousness, as language?
Structure: 4 marks
Content: 12 marks
mind 8 marks
disorders 4 marks
Understanding: 4 marks
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