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Overview: I hope this lecture shows you that the scientific method is not as impersonal and dry as it sometimes appears. You will learn where scientific questions come from, and begin to appreciate the motivations of scientists who are interested in the biological bases of behaviour. Parkinson's disease is used as an example of a distressing human condition that may be amenable to a biologically based treatment. You will begin to appreciate the sheer number of people whose lives are devastated by psychiatric illness. Phrenology is used as an example of a theory which failed for several reasons: it was not supported by experimental evidence; and the technique was adopted by charlatans wanting to make 'a fast buck'. Nevertheless phrenology contains a grain of truth that has fuelled most of the work in psychobiology during this century - namely the notion of localization of function.
Scientific journeys can start from the wish to test a theory,
to find a solution to a problem , or
just plain hunch.
The next diagram manages to convey a rather dry and boring feeling
about science. It
really isn't like that at all. It can be the battleground for clashes
between massive egos
- you will meet plenty of those on your journey. But above all science
is a public
activity - with the communication of results at its
communication of results doesn't get a look in on this diagram. As I
said in the lecture in
my book it isn't science without public disclosure of methods and
results. A full
description of the method allows for replication in other labs by other
there that your results will come under the sharpest scrutiny when the
question is asked
"Does this result replicate?" The
Introduction and Discussion
sections of a scientific paper are where you can detect the clash of
Do you think everyday human thought relies on the scientific method, or does it need to be taught?
is agreed by scientists that species that now exist originate from very
simple forms of life that existed millions of years ago.
Darwin gave us an important theory of how evolution
occurs. It has been called "the single best idea anyone has ever had".
|Is Darwin's theory
free of 'cultural values'? This section contains a
set of optional readings, but it also contains details on how to spot a
good scientific theory.
In recent years a 'Darwin industry' has developed involving historians attempting to understand, unravel, and interpret the cultural influences on Darwin, and Darwin's influence on culture. There is very clear coverage of the cultural context and impact of Darwinian theory in:
When Darwin published his theory of evolution in 1859 it generated less controversy than we are sometimes led to believe. On the contrary, it was generally well accepted. Darwin's theory did not come as a 'bolt out of the blue' to an unsuspecting audience. In fact, Darwin was not alone in proposing a theory of evolution. There were already several accounts of evolution, but they were fundamentally different to Darwin's.
Pre-Darwinian theories postulated that evolution was the progressive unfolding of a purposeful plan involving a linear trend of increasingly complex species that culminated in the appearance of humans i.e. the natural world was considered to be a scala natura. These were evolutionary theories - in the sense that they rejected the picture of creation presented in the Book of Genesis - but they allowed space for God to operate as the master planner of a gradually improving world. But careful reading of Darwin's theory shows that it does not admit a purposive plan, and does not imply that humans as the highest rung on an evolutionary ladder. Instead it suggests that the mechanism underlying evolution feeds random variation between individual members of a species into a filtering mechanism composed of environmental pressures.
Evolutionary theories were welcomed by some in the mid nineteenth century; they offered a progressive way forward for a society dominated by church and aristocracy. But they were treated with suspicion by others because they threatened to abolish the special place of Man in the natural world, and disrupt a relatively stable social structure that had seen fundamental political upheavals in nearby France. Perhaps Darwin's theory of evolution was better adapted than others to survive in the scientific and social environment that existed in England nearly 150 years ago.
Bowler suggests that in 1859 readers interpreted the main message of the Origin of Species in line with the cultural beliefs of their times:
Darwin may have colluded with this misinterpretation to facilitate popular acceptance of his theory. Ruse (1999) argues that Darwin believed in social progress and this is increasingly evident in later revisions of the Origin of Species. For example, in the third edition published in 1861 he wrote that "natural selection clearly leads towards highness" (see Ruse 1999, p69-70).
Furthermore, Darwin seems influenced by the values of his social class, upbringing and circle of acquaintances. Ruse points out that in Darwin's book on human evolution - The Descent of Man - published in 1871, "Darwin brought in all of the cultural values of his sex, race and class. Not only do we learn that men are string and brave and brainy, whereas women are kind and gentle and sensitive; that whites are intelligent and hardworking whereas blacks are stupid and lazy; but that, on the whole, capitalism is no bad thing."
Darwin was highly respected during his lifetime - both before and after publication of the Origin of Species - and this is reflected in his resting place: He was buried next to that other national scientific hero, Sir Isaac Newton, in Westminster Abbey in 1882. And his fame lives on: In 2003 Darwin was voted the most important Briton of all time in a national survey organised by the BBC.
But you are now faced with a problem. Should you criticize Darwin's theory because it was tainted by cultural factors from an earlier period of our history? Or do you accept that Darwin, like all of us, is a product of our time and culture, but nevertheless he had an important insight into a reality that exists independently of time and culture?
Reading Ruse (1999) Chapter 1 "Karl Popper and Thomas Kuhn: Two Theories of Science" may help resolve this dilemma. The power of Ruse's (1999) evaluation of Darwin's influence comes from his analysis of:
Epistemic values or "scientific values" are a set of characteristics of a scientific theory that reveals a reality that - we assume - exists outside ourselves, and exists independently from us (i.e.' truth'). Ruse draws on work by McMullin to draw up a list of epistemic characteristics or "scientific values" which include:
Non-epistemic or "cultural values" factors refer to
Examination of the Darwin's life and times shows the influence of non-epistemic cultural values on the genesis of his theory, and particularly its development by his disciples. Furthermore, the epistemic qualities of evolutionary theory has had a powerful feedback effect on cultural values in the last century. For example, the use of metaphor such as Dawkin's 'selfish genes', and value-laden phrases such as 'survival of the fittest' (which was adopted by Darwin from Herbert Spencer), and "the struggle for existence" have entered the popular imagination.
When it was first published, Darwin's theory was not as epistemically strong as it is now. Ruse provides a convincing case that Darwin's theory contained several epistemic weaknesses:
Evolutionary theory now forms the paradigm for the biological sciences. A paradigm is a body of theory, results, methods, and set of acceptable questions that are embraced by the vast majority of people working in a particular discipline. It is a generally accepted way of doing science (see Ruse 1999, p19). You may be wondering what paradigm binds together all psychologists. I can't give you the answer.
I started my undergraduate studies in Zoology, Physiology and Botany so was immersed in the evolutionary paradigm from a tender age. But then I switched to psychology where a favourite student-discussion question used to be "Is psychology a science". I used to thoroughly enjoy arguing with friends that 'psychology is a pre-paradigmatic junk yard full of cognitive scrap metal'. Read about Thomas Kuhn's views on scientific paradigms in Ruse Chapter 1 if you want to continue this time-honoured student drinking game.
Here is an example of theory construction and the scientific method applied to a current problem.
|The Austrian physician
Franz Joseph Gall (1758-1828) suggested that the brain was the location
of all mental activities. He collected the skulls of criminals and
busts of famous men. Gall postulated that the surface of the skull
would mirror the exaggeration of functional areas in the cortex so that
he could correlate bumps in the skull with faculties prominent in
certain individuals and created a map locating particular mental
functions in particular areas of the cortex. This became Phrenology,
which claimed that mapping the bumps on a person's head would give
indications of the capabilities and personality of the individual. Adapted
from The Brain
Project by Stephen Jones.
Although today phrenology is not regarded seriously, Gall did express important insights. For example he wrote: "that the cerebral cortex represented the highest level of the brain and that the development of this area characterized mammals and man."
|"In the early 19th
century, Phrenology gained a rapidly growing interest. Some
unscrupulous people did however abuse the science for commercial
purposes, and the Victorian period saw the emergence of Phrenological
parlours which were closer to astrology, chiromancy, and the like, than
to real scientific characterology. Unfortunately, those con-men have
done a lot to stain the image of Phrenology as a real science, and
their bad influence lives up to today." Quotation from Phrenology
by Peter Van den Bossche
The most serious challenge to phrenology came from Paul Flourens, (French), who developed the 'ablation' (or surgical removal) experiment. He removed areas of the cerebral cortex of animals but did not observe clear-cut specific changes in behavior. Flourens wrote: "a large section of the cerebral lobes can be removed without loss of function. As more is removed all functions weaken and gradually disappear. Thus the cerebral lobes operate in unison for the full exercise of their functions."
It is now known that damage to specific parts of the brain can lead to behavioural changes. In 1861, Paul Broca described the case of a man who - when he was alive - appeared normal except that he was unable to speak. When he died, Broca autopsied the man's brain and found a lesion of the left frontal lobe of the left hemisphere. This loss of the language faculty is known as `aphasia'. Broca's observation marks the beginning of an idea known as localization of function.
Why do you think phrenology is dismissed as pseudo-science?
There is a grain of truth in the phrenologists claim that ' faculties
within the brain '. Nowadays this insight is referred to as Localization
Function . Put simply localization of function
holds that parts of the brain are
specialized to carry out particular functions. Localization of function
is the bedrock of
contemporary research into the relationship between brain and
behaviour. It is the belief
that we can ultimately understand how the brain controls our behaviour.
Why would we want
this knowledge? One very good reason is that it may help us understand
what happens when
behaviour becomes disturbed. For example, the next section of the
lecture gives you some
idea the enormous number of people who suffer because of brain
Please don't get the idea that I, or any other neuroscientist for that matter, believes that psychiatric illness is simply the result of abnormal brain chemistry. It isn't. Clearly an individual's external environment may play an important role in the development of these very distressing conditions. But there is a complex interaction between a person's internal and external environment.
Put simply: The brain affects behaviour and behaviour affects the brain.
|Parkinson's disease provides a very clear example of the application of the scientific method to the alleviation of human suffering. Over one million Americans suffer from this disease which usually strikes the over 40's. This section begins by describing the symptoms of Parkinson's disease and its progression. Although drugs can be used to treat the symptoms, not all patients respond well to these medicines, and they do not offer a cure for Parkinson's, only relief from its symptoms. Therefore we will examine an example of a ground breaking series of experiments involving an animal model of Parkinson's disease which offer the hope for a new form of treatment involving tissue transplantation into a part of the patient's brain that is affected by the disease.
|Tremor of one hand is a
frequent early manifestation of parkinsonism
|Tremor often improves or
disappears with purposeful function
|Difficulty in performing
simple manual functions ( e.g. doing up a shirt button )
may be initial symptom
Writing shows 'micrographia' (small size) and effects of tremor
Improvement after L-DOPA therapy
Stages in the development of parkinsonian symptoms .
(a) Stage 1 : unilateral involvement; blank faces; affected arm in semiflexed position with tremor; patient lean to unaffected side.
(b) Stage 2: bilateral involvement with early postural changes; slow, shuffling gait with decreased excursion of legs.
(c) Stage 3: pronounced gait disturbances; moderate generalized disability; postural instability with tendency to fall .
Last stages in the development of parkinsonian symptoms.
(d) Stage 4; significant disability; limited ambulation with assistance.
(e) Stage 5; complete invalidism; patient confined to bed or chair; cannot stand or walk even with assistance.
disease is thought to be caused by a breakdown in communication between
areas of the brain: the substantia nigra and the striatum (the striatum
consists of two
structures: the caudate nucleus and the putamen). The striatum controls
and walking. Cells in the substantia nigra synapse with cells in the
striatum. Dopamine is
the chemical messenger released at these synapses. Patients with
Parkinson's disease are
missing about 80% of the cells in the substantia nigra, and there is a
of about 80% of dopamine in the striatum.
the disease involve replacing this lost
dopaminergic function. The most common treatment involves giving the
patient the drug
L-DOPA which is converted into dopamine in the brain.
Results of L-DOPA therapy
Moreover in the long term:
there is still a need for research into causes and treatments for this
One avenue of research is attempting to develop a Tissue Transplantation Therapy . This involves replacing damaged cells in the patient's brain with new cells that synthesize the chemical dopamine. This therapy has its roots in groundbreaking basic research in animals such as that carried out by Dunnet in Cambridge, UK.
Introduction to Dunnet's experiments
Here is a picture of the Rotometer Dunnet used
in his experiment A wire
connected to the recorder extends from a harness fitted around the
rat's chest. This
device records circling behaviour in rats. The hemisphere-shaped bowl
tends to encourage
circling behaviour in amphetamine treated rats.
This figure shows the results of Dunnet's
experiment on the effects of dopamine-rich
grafts on amphetamine-induced rotation.
Rotation in intact control rats (the bottom line), rats with unilateral nigrostriatal lesions, and rats with unilateral nigrostriatal lesions + dopamine-rich ( DA graft ), serotonin-rich (5-HT graft ), or striatal (CPu graft ) cell suspension grafts into the denervated host neostriatum. The lesions induce a marked turning asymmetry, which is alleviated only in the group receiving DA-rich grafts.
In one subgroup of rats with DA-rich grafts, the grafts were lesioned by an injection of the neurotoxin 6-hydroxydopamine (6-OHDA) (indicated by the arrow above the line representing the DA graft removed group). Destruction of the DA cells in the graft reinstated the initial rotation asymmetry.
Source of DA neurones [from Antiparkinsons Pravin K. Mishra, Ph.D. ]
Do you think Parkinson's disease is a psychiatric illness?
Medications for Parkinson's disease can be effective, but they sometimes wear off too soon. Discover what's being done to allow patients to get longer responses to their treatment.
Parkinson's disease generally affects people in later life, but there are inherited forms of the disease (e.g. autosomal recessive juvenile parkinsonism) that affect younger people. In the 9 April 1998 issue of Nature, a group of Japanese scientists report that they have identified the gene for one of these early-onset forms of parkinsonism.
is a link to a recent Behavioral & Brain Sciences article which
covers transplantation in great detail
OVER PARKINSON'S DISEASE IN SIGHT!
The Harvard Mahoney Neuroscience Institute Letter FETAL
NERVE CELL TRANSPLANTATION: ADVANCES IN THE TREATMENT OF PARKINSON'S
Eric Chudler's pages provide easy to follow background information on a number of topics: