The input from brain research

Question 1

What was the Edwin Smith Papyrus?

Answer 1

papyrus from Ancient Egypt that contains short descriptions of the symptoms and treatment of different forms of brain injury; named after the person who bought the papyrus in Egypt and had it analysed. It shows illustrates how physicians treating wounded soldiers quite early became convinced of the importance of the head (brain) in controlling behaviour.

Question 2

What were the roles of the heart and the brain in Ancient Greece according to 1. Plato, 2. Aristotle and 3. Galen?

Answer 2

Plato: According to Plato, the soul was divided into three parts. The highest part, responsible for reasoning, was situated in the brain. It came directly from the soul of the universe, was immortal, separated from the body, and it controlled the body. The second part of the soul dealt with sensation, was mor- tal and situated in the heart. To avoid it polluting the divine soul, a neck separated the two. Finally, the lower part of the soul dealt with appetite and was placed in the liver, far away from the other two.
Aristotle: Aristotle was convinced that the heart was the seat of the soul. The function of the brain in Aristotle’s view was to counterbalance the heat of the heart.

Question 3

Why did Aristotle believe the Humans brain was larger than other animals?

Answer 3

he human brain relative to the body was larger than that of other animals because man’s heart was hotter and richer and needed a stronger counterbalance for good performance.

Question 4

Name a philospoher, six centuries after Aristotle that came to the conclusion that the brain was where the ‘soul’ was and how he came to that conclusion

Answer 4

Galen (c. 130–c. 200 CE) started to experiment on animals. In one of his experiments Galen found that a pig stopped squealing, but kept breathing, immediately after he severed nerves in the throat, thus demonstrating that the voice came from the brain and not from the heart. Galen also dissected brains and published drawings of them.

Question 5

Another problem Galen had to solve was how the brain communicated with the rest of the body. The heart was connected to all parts of the body through the blood in the veins, but how did the brain communicate?

What conclusion did Galen come to?

Answer 5

Galen did not think the brain itself was important for reason or emotion but for the soul residing inside the brain. The soul lived in the solid parts and produced and stored animal spirits in the apertures in the middle of the brain, called the ventricles. By means of these spirits the soul communicated with the rest of the body. The spirits travelled between the soul and the organs via the nerves, which were assumed to be hollow tubes.

Question 6

Name three points about brain research which took place during the renaissance

Answer 6

• Andreas Vesalius (1514–1564) resumed dissections and extended them to humans, he persisted in Galen’s preoccupation with the correct drawing of the ventricles and did not care much about the convolutions of the brain, which he carried on depicting as intestines
• Vesalius further established for certain that there were three ventricles and attributed purposes for these ventricles
• With the rediscovery of Galen’s texts, researchers also regained interest in the relationship between brain injuries and behaviour. (Speech problems can be caused by brain injury)

Question 7

What purposes did Vesalius assign to the three ventricles

Answer 7

The front ventricle was assumed to receive information from the senses and, therefore, was called the common sense. It also included fantasy and imagination. The second ventricle, in the middle of the head, comprised thought and judgement. Finally the third ventricle, at the back of the head, contained memory.

Question 8

Name and describe three developments of the brain in the seventeenth and eighteenth centuries

Answer 8

The brain instead of the ventricles- In the seventeenth century they started to pay attention to the difference between the outer layer of the cerebral hemispheres (the parts of the brain with the convolutions), which looked greyish, and the layer underneath, which had a white appearance.

• Increased interest in reflexes-
• A proposed treatment for brain injury

Question 9

Why is our autonomic nervous syste known as the sympathetic nerve system?

Answer 9

Galen had already noticed that sometimes animals performed involuntary acts, which he ascribed to ‘sympathy’ between the various body parts, so that one could respond sympathetically to another’s distress.

Question 10

Which two other researchers contributed to knowledge on reflexes in the 17th and 18th centuries?

Answer 10

Descartes argued that a reflex consisted of a sensory impression which rushed to the brain and subsequently was reflected back (as in a mirror) into a motor command to bring about the required action.

In 1784 the Czech physiologist Jirˇí Procháska published a book in which he argued that reflexes were not controlled by the brain but involved the spinal cord and the structures just above it.

Question 11

What problems arised with the new view of the importance of the cerebral cortex and the white matter being the important parts of functioning?

Answer 11

The brain seemed to be numb. How then could it be involved in sensation and movement? If you exposed the grey matter and touched it, the animal did not seem to be disturbed. However, if you touched the white matter or went into the ventricles, the animal screamed, sometimes showed involuntary movements, and often died.

Question 12

What five breakthroughs formed a series in the nineteenth century and irrevocably altered the model of brain functioning and made modern neurophysiology possible ?

Answer 12

1. the discovery of the cerebrospinal axis
2. the growing impact of the reflex
3. the localisation of brain functions
4. the discovery of the nerve cell
5. the disentangling of the communication between neurons.

Question 13

What observation lead to the discovery of the cerebrospinal axis?

Answer 13

researchers began to realise that a body remained functioning in a vegetative state when the cerebral hemispheres were taken away or disconnected from the structures at the top end of the spinal cord (nowadays called the subcortical structures). So, there were many bodily functions that did not seem to require the cerebral hemispheres.

Question 14

Researchers also started to pay more attention to the nature and function of reflexes in brain functioning. An important figure in this respect was the British physician and physiologist Marshall Hall (1790–1857). What did Marshall introduce? Explain

Answer 14

He introduced the notion of the reflex arc to refer to the mechanisms involved in involuntary movements elicited by sensory stimuli; a signal is picked up
by sensory receptors, transmitted to the spinal cord through an afferent nerve, transferred to interneurons, which activate motor neurons that send a motor command over an efferent nerve to initiate the withdrawal movement

Question 15

Some time later, researchers extended Hall’s reflex arc from the spinal cord to the complete brain. For them, the reflex was no longer one mode of action in the nervous system among others, but… ?

Answer 15

the basal unit from which the remaining nervous functions evolved

Question 16

What important researcher did this influence at that time?

Answer 16

One of the scholars who took this view was the Russian physiologist Ivan Sechenov. In 1863 he published a theoretical treatise under the title Reflexes of the brain, in which he claimed that all higher functions of the brain were of a reflex nature. Sechenov’s treatise was important because it influenced Pavlov, who was a student of his.

Question 17

What is meant by the brain equipotentiality theory?

Answer 17

theory saying that all parts of the brain have equal significance and are involved in each task; first thought to apply to the complete brain; since the nineteenth century limited to the cerebral hemispheres

Question 18

What theory was in contrast to the brain equipotentiality theory?

Answer 18

localisation theory; theory saying that brain processes are localised, meaning that only part
of the brain underlies a particular mental function

Question 19

Name three early nineteenth century discoveries that gave evidence for localisation theory

Answer 19

• Language production is controlled by the front parts of the brain
• Language production is controlled by the left frontal lobe
• Language understanding and the posterior part of the brain

Question 20

What evidence did the French professor of clinical medicine and a student of Gall, Jean-Baptiste Bouillaud which according to him proved that speech was controlled by the front parts of the brain?

Answer 20

In a paper read to his colleagues he reviewed the data from 14 autopsies. Eight patients with speech problems all had lesions in the frontal lobes of the brain, whereas these lobes appeared to be intact in the six other patients without speech disorder. In 1848 he presented a large number of new cases to support his theory.

Question 21

Who repeated and extended Bouillaud’s work and presented evidence to the Société d’Anthropologie that speech production was controlled by the frontal lobes?

Answer 21

Paul Broca, professor of pathology in Paris

Question 22

How did Broca extend this theory

Answer 22

In 1865 he went further and claimed that only a region in the frontal lobe of the left hemisphere was involved.

Question 23

Who further extended this theory and how?

Answer 23

the German-Polish physician Karl Wernicke in 1874 presented evidence that language problems could also occur after damage to the rear part of the left hemisphere. These problems, however, had nothing to do with speaking, but rather with the understanding of language. The patients at first sight gave the impression of fluent speakers, until you tried to make sense of what they were saying; there was no meaning in their language.

Question 24

What two technical innovations were needed for the discovery of the nerve cell?

Answer 24

The availability of better microscopes

New techniques to stain the brain tissue

Question 25

What was used to colour the brain cells and how did this help?

Answer 25

silver; This technique made the neurons stand out against the surrounding cells and revealed that they not only consisted of globules (cell bodies) but in addition comprised a highly interconnected network of branches

Question 26

What was the fourth big breakthrough in the nineteenth century concerning grey and white matter?

Answer 26

the grey matter of the cerebral hemispheres consisted of billions of cells and that the white matter and the nerves were the ‘tails’ (later called axons) of these cells.

Question 27

What two problems were there with the assumption that brain fluids in the nerve cells were able to transmit information from and to the brain?

Answer 27

There was difficulty accounting for the speed of neural transmission (which easily exceeds 100 km per hour). In addition, there was the problem that no-one was able to show the presence of fluid in the nerves.

Question 28

What was the solution to these problems involving brain fluid and why did people think this?

Answer 28

round 1650 the first electricity generator was built, followed in 1745 by the first usable device to store electricity, the so-called Leyden jar. With the help of a generator and a Leyden jar scientists could study the characteristics of electrical currents. Physiologists were struck by the similarities between electrical signals and what happened in the nerves (a signal was transmitted at a high speed and at the end made something happen).

Question 29

Who showed empirical evidence for this and how?

Answer 29

Italian physician Luigi Galvani. In 1786, while operating on frogs, he noticed that a dissected leg of a frog contracted each time his assistant touched a bare nerve with his scalpel and the electricity generator nearby produced a spark.

Question 30

Another question was whether nerves were like real electrical wires or whether the electrical signal generated was based on chemical processes within the nerve. What was the answer and how was this shown?

Answer 30

von Helmholtz in 1852 decided to measure the speed of signal transmission in the nerve. If nerves were like electric wires, the signal speed should be astronomically high (close to the speed of light). Alternatively, if the signal was based on chemical processes, as von Helmholtz assumed, it would be much slower. The latter was the case: the speed of the nerves in the leg of a frog was only some 30 metres per second

Question 31

In what century did the communication between neurons also become understood?

Answer 31

20th century

Question 32

When is electrical information and when is chemical information usually transmitted with nerve cells?

Answer 32

electrical information mainly involved in intra-cell communication, chemical information transfer important for communication between neurons

Question 33

Localisation studies continued in the twentieth century. In particular the World Wars resulted in new insights. Why?

Answer 33

The invention of high-velocity bullets had the unforeseen consequence that brain wounds were more focused than before, allowing researchers to get a sharper image of function loss after damage to small parts of the brain.

Question 34

Similar observations were made in World War II. A particularly important paper here was that of the German physician, Joachim Bodamer (1947), describing soldiers who suffered an injury to the rear of the brain. What were the symptoms of this injury?

Answer 34

They lost their ability to recognise faces (prosopagnosia)

Question 35

In the 1970 and 1980s, a number of neuropsychologists became dissatisfied with the way in which the subject matter was investigated. They had two grievances. What were these grievances?

Answer 35

The localisation issue turned out to be difficult to address on the basis of human brain injuries.

the results of the examinations rarely went beyond a list of symptoms displayed by various patients (case studies). There was little theory behind the enterprise, little effort to link the various findings and draw implications for normal, healthy functioning.

Question 36

Give two reasons why the localisation issue turned out to be difficult to address on the basis of human brain injuries.

Answer 36

All that could be done was to establish a correlation between symptoms measured while the patient was alive and brain damage observed much later, after the patient had died

The damage caused by brain injuries and strokes is usually widespread and not limited to one specific brain structure, making it difficult to decide which part of the damage was at the origin of the symptoms.

Question 37

What new field did this lead to and where did they lay their focus?

Answer 37

Neuropsychologists wanted to use observations from patients with brain damage to test and amend the information-processing models proposed by the cognitive psychologists. Instead of looking for anatomical localisations, neuropsychologists should investigate the functional implications of injuries. To emphasise the difference between the new type of research and the traditional neuropsychological approach, a new name was coined: cognitive neuropsychology.

Question 38

What is meant by deep dyslexia?

Answer 38

Deep dyslexia is a condition of strongly impaired reading after brain injury with a very particular symptom: sometimes, when patients try to identify a word, they do not read the word itself but a semantically related word.

Question 39

How did Morton and Patterson (1980) attempt to explain this?

Answer 39

postulated a distinction between a logogen system and a cognitive system. The logogen system could be compared to a mental dictionary; it contained all the words known to a patient (later the name ‘lexicon’ was used for this system). The logogen system did not contain information about the meaning of the words; this was stored in a central cognitive system with which the logogen system interacted. Written words were recognised by first activating their entry in the visual logogen system and then by activating the corresponding meaning in the cognitive system.

Question 40

What three different logogen systems did Morton and Patterson (1980) argue existed?

Answer 40

a visual logogen system for the recognition of written words, an auditory logogen system for the recognition of spoken words, and an output logogen system for the production of speech

Question 41

Within the full model there were three routes for a normal reader to read aloud a written word. describe these three routes and their implications regarding abilities

Answer 41

The first route directly con- verted the letters into sounds; this one was called the grapheme phoneme conversion route. It allowed readers to name non-words, such as dom and pham. The second route consisted of a direct connection between the visual logogen system and the output logogen system. The existence of such a route predicted that there would be patients who were able to name words with irregular pronunciations (e.g. yacht, pint) without knowing their meaning. Finally, the third route to name written words was one via the visual logogen system, through the cognitive system, to the logogen output system. In this route the visual logogen activated its meaning and on the basis of this meaning candidate output logogens were activated.

Question 42

According to Morton and Patterson (1980) which route was the origin of the semantically related errors observed in deep-dyslexia patients? How did they explain this?

Answer 42

Third route; In these patients the grapheme phoneme conversion route and the direct route between the visual logogen system and the output logogen system were severed. All they had left was the route mediated by the cognitive system. Because this route was not very accurate, they failed to read a lot of words altogether and other words gave rise to semantically related responses.

Question 43

For a long time the evidence about the neurophysiology of the brain and the localisation of functions was based on post-mortem analyses. In the twentieth century, however, scientists increasingly managed to extract information from a working brain.

Name one of the first techniques to do this and how it worked

Answer 43

One of the first techniques used was single-cell recording. In this technique electrodes were planted in individual brain cells and recorded when the cells fired. By presenting different types of stimuli, researchers could determine in which processes each cell took part.

Question 44

Why was the use of these single cell recordings very limited and how was this resolved?

Answer 44

because this technique involved brain surgery and the insertion of electrodes in the brain; Eventually, however, brain imaging techniques became available that did not require the researchers to touch the brain. These are called non-invasive techniques.

Question 45

In 1928 the German physician and psychologist Hans Berger published an article that would dramatically change brain research.

What was the subject matter of this article?

Answer 45

He reasoned that if brain activity was electrical activity, he might be able to pick up some signals if he put electrodes on the human scalp. Berger indeed found very weak signals that seemed to oscillate at a frequency of some 10 cycles per second, at least when the person was at rest with their eyes closed. As soon as the person opened their eyes or was touched on the skin, the regular signal disappeared and was replaced by smaller and faster oscillations, which disappeared again when the person closed their eyes and returned to rest

Question 46

What was Berger’s new method of the measurement of brain activity called?

Answer 46

Berger called the printout of the electrical brain activity as a function of time an electroencephalogram, better known under its abbreviation EEG.

Question 47

What name did he give the waves associated with the brain activity?

Answer 47

He further called the slow, regular waves at rest alpha waves, and the fast, irregular waves under situations of alertness beta waves.

Question 48

Name two of the first applications of EEG

Answer 48

One of the first applications of the EEG measurement was the demonstration that epileptic seizures involved uncontrolled electrical discharges. Another application was the discovery of different sleep stages.

Question 49

As the accuracy of the EEG recordings grew, two further applications became available. Name these two applications

Answer 49

Event Related Potential (ERP) research

One could try to localise the source of the electrical signal.

Question 50

Explain Event Related Potential (ERP) research

Answer 50

In this type of research, two types of stimuli are presented repeatedly and researchers examine in what respects the brain response to one type of stimulus differs from that to the other.

Question 51

How successful was EEG in localising the source of the electrical signal? Explain how EEG was used to measure this

Answer 51

In a recording up to 128 different electrodes are placed on the head. Not all of these electrodes return an equally strong signal. Depending on the distribution of signals, it is possible to have an estimate of the part of the brain that was at the origin of the signal. Unfortunately, because of the limit to the number of electrodes that can be placed on the head (and because of the small errors involved in the placement itself), localisation on the basis of EEG recordings is not very accurate.

Question 52

How can a much better resolution be obtained, also through measuring the electrical brain activity?

Answer 52

A much better resolution can be obtained if researchers measure the magnetic field around the head. The electrical signals in the brain produce magnetic fields, which can be picked up by sensitive sensors. This forms the basis of magnetoencephalography (MEG), a technique which is still in its early stages but which is expected to have a very significant impact.

Question 53

Name one of the first methods of measuring blood flow in the brain and how it works

Answer 53

One of the first techniques consisted of injecting a radioactive tracer into the blood circulation and detecting the radioactive signal. The more blood a certain region requires, the more tracer goes to that area. This was the basis of PET (positron emission tomography)

Question 54

Give two reasons why PET is now rarely used

Answer 54

because of the need to use radioactive material and because the precision of the measurement is limited.

Question 55

Name another method of measuring blood flow in the brain and how it works

Answer 55

fMRI (functional magnetic resonance imaging) measures the magnetic resonance of the blood. This differs between blood with oxygen and blood without oxygen. Measurement of the magnetic resonance makes it possible to determine which regions of the brain are using a lot of oxygen (and thus are very active).

Question 56

Name two advantages of fMRI compared to PET

Answer 56

more accurate measurements can be made and that the investigation takes place without the need for an injection.

Question 57

What is a limitation of fMRI?

Answer 57

A limitation of the technique is that at present the oxygen use can only be registered at a rate of a few times per second, so that researchers cannot measure the detailed processing that is going on

Question 58

How can one measure the effects of ‘virtual lesions’?

Answer 58

Because brain activity is electrical activity, it is possible to interfere with it by inducing a weak electric current in the neurons. Interference with the electrical activity of neurons in a restricted brain area is the basic mechanism behind transcranial magnetic stimula- tion (TMS). A coil is placed on the head of the person and a focused electric current is sent to the grey matter underneath.

Question 59

How is TMS complementary to fMRI?

Answer 59

because fMRI only allows researchers to see a correlation between activity in certain brain regions and performance on a particular task. It does not tell researchers whether the brain activity is necessary for the behaviour. Such a conclusion is only possible with TMS. By interfering with the activity of an area, the researchers can examine whether the region is critical for good task performance.

Question 60

What is meant by cognitive neuroscience?

Answer 60

Just as neuropsychological information was used to test cognitive models of information processing, so did psychologists increasingly rely on brain imaging data to test their theories. This branch of research became known as cognitive neuroscience, the scientific study of the biological mechanisms underlying cognition.

Question 61

Name two criticisms cognitive neuroscience faced

Answer 61

According to some authors, the findings of fMRI are more comparable to the localisation efforts of traditional neuropsychology (sometimes mockingly referred to as ‘blob spotting’) than to the testing of cognitive models done in cognitive neuropsychology.

Kihlstrom (2007) went even further and argued that the conclusions based on brain imaging have a strong resemblance to the claims made by the nineteenth-century phrenologists.

Question 62

Needless to say, cognitive neuroscientists strongly disagree with the claim that their studies are unable to provide anything more than information about the localisation of brain activity. `Give three of their main arguments

Answer 62

First, there is a difference between empirically showing the brain regions involved in a particular task and speculating about them.
Second, localisation of the brain activity while a person is performing a task does provide information about the processes involved. For instance, brain regions normally involved in moving the feet are activated when participants see a picture of a person kicking something or are asked to read the word ‘kick’. This suggests that activation of movement commands is part of the understanding of actions and words referring to actions. This information (and the ensuing changes in theories of how people understand concepts) would not have been there without brain imaging.
Third, on the basis of brain imaging data it is now recognised that, although the brain is compartmentalised into regions with specialised functions (as defended by the localisers), all tasks (even the simplest) require the interaction of several areas distributed over distant parts of the brain. This too was not realised before the start of cognitive neuroscience. In addition, although brain areas are specialised, they are involved in several tasks with different stimuli.

Question 63

It might even be argued that the discussion about equipotentiality vs. localisation has been settled to a large extent by what two findings?

Answer 63

The overlap of functions in brain areas and the cooperation of different, distant parts of the brain