Intro to Clinical NeuroPsych 2022-2023
Introduction to Clinical NeuroPsychology | The Book
Chapter 1 | Clinical neuropsychology: a historical outline
Already 400 BC, Hippocrates taught that an abnormal behaviours and emotions
stemmed from the workings of the brain. Then René Descartes (1596-1650) believed that the
soul was located in a cavity in the head, namely the pineal gland or epiphysis. Franz Joseph
Gall (1750-1020) proposed a completely different approach, namely that there are many mental
organs located in the gray matter or cortex of the brain. This resulted in the development of
phrenology. Gall's ideas were tested using the so-called clinico-anatomical method. This
involved studying the cognitive loss of function in the areas of e.g., language or memory, in
patients with brain injury, and subsequently after the death of the patient, linking the location
of the lesion to the type of functional impairment.
Cell theory
A question that has always been important in the brain-behaviour debate is that of
localisation. The Ancient Greek had three different forms of the soul. They called the guiding
principle the psychikon hegemonikon, the Latin spiritus animalis.
A few philosophers noted cavities in the brain - the ventricles- which were at that time called
cells. These cells were considered to be the site of the mind. The first cell was assumed to
receive the information from various senses; this cell was called the sensus communis. The
second cell was believed to interpret the image (a psychological representation;
vision/imagination). The image was then stored in the third cell, memoria, or memory.
René Descartes: an undivided mind
René Descartes lived during the Renaissance era. His most famous axiom is "I think,
therefore I am". His basic principle is that he regarded people as composed of two substances:
the body (res extensa) and the mind (res cogitans). Although the mind is not material and does
not take up any space, Descartes believed it had a specific location, the pineal gland or
epiphysis. He regarded the res cogitans as a kind of manager.
Gall and the localisation issue
Franz Joseph Gall wanted to create a new psychology, which he preferred to call
organology or craniology (phrenology). He assumed that all psychological functions were
innate. He stated that each of these functions was concerned with an independent organ.
The clinico-anatomical method
The method that was used to test the localisation ideas by Gall and Jean-Baptiste
Bouillaud and by charting the specific loss of function in patients with focal encephalopathy
was called the clinico-anatomical method. By this method, Broca's area has been discovered.
At that time, it was a rule in physiology that the shape of an organ determined its function, and
if two organs had the same shape then they also had the same function. Therefore, in theory,
the two sides of the brain could not have different functions (i.e., Broca's area could not be true
as that would mean we speak with the left side of our brain).
After Broca, Wernicke continued the topic and discovered Wernicke's Area. He
proposed language consisted of a set of different functions, not only production but also
comprehension.
John Locke was a strong advocate of empiricism - he did not believe in innate
characteristics and knowledge. Everything was learned, and learning was accomplished through
the principle of association, associatism, as described by Aristotle.
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Holism
Holism is an approach to understanding the human mind and behaviour that focuses on
looking at things as a whole. It is contrasting with localisationism.
! Luria: a global model !
Luria sought a balance between holistic and localisationistic views. He regarded the
whole brain as a single complex functional system within which various subsystems contribute
to joint activity.
Luria summarised the functional architecture of the brain using 3 broad classifications:
- 3 continually interacting functional units, relating to the subcortical, posterior, and
anterior parts of the brain ('activation', 'input' and 'output', respectively).
- 3 hierarchically organised levels of processing, related to primary, secondary, and
tertiary zones in the brain.
- Behaviour that is or is not regulated by language processes, related to the left and right
hemisphere, respectively.
The three functional units:
1) The first unit is to regulate alertness and attention.
2) The second unit processes cognitive information (perception, processing, storage).
3) The third unit is used to organise behaviour (planning, regulating, and monitoring of
goal-directed activities).
Luria placed the greatest emphasis on the far-reaching significance of language and in
particular of internal speech for the regulation of cognitive, emotional, and planning functions.
An initial impulse: the test battery
The Halstead-Reitan Neuropsychological Battery were intended to chart various
psychological functions. Similar is the Luria-Nebraska Neuropsychological Battery (LNNB),
developed by Charles Golden in 1981, based on Luria's ideas and test procedures.
! Neuropsychology as an independent discipline !
Norman Geschwind was important for neuropsychology to become its own discipline.
Geschwind became familiar with the work of Wernicke and encouraged many people to look
for specific centres and links in order to more accurately chart the functioning of the brain, and
focus on the analysis of functions. An important aspect of this involved looking for double
associations - one can more or less establish independent functions if, in the case of a lesion at
location X, function A is affected but function B is not, and if in the case of a lesion at location
Y, function B is lost but not function A.
Another important figure for neuropsychology to become its own discipline was Roger
Sperry, who carried out research on the effects of split-brain surgery. In this surgery, the fibre
tract between the two hemispheres (the corpus callosum) is cut through. Interestingly, the
negative side effects of cutting through roughly the largest fibre tract were very limited.
However, after studying patients with split brains, it was discovered that the right side of the
brain was better at performing certain functions than the left side; the idea of a dominant left
hemisphere was replaced by the idea of hemisphere specialisation. This discovery ensured that
neuropsychology became a specialty in its own right. The precise assessment of the nature and
severity of disorders became part of the profession.
Cognitive neuropsychology
What do we mean by a function and a localisation? Language philosopher Jerry Fodor
believes we have no awareness of language processes, and we do not have any control over
them. This type of process is referred to as a module. It therefore makes a clear distinction
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between representation (the information that can be processed by a module or produced as
output) and a process (the calculations, computations, or transformations that are carried out
on the representations). Fodor formulated several characteristics with which a model has to
comply:
1. It’s domain specific.
2. It has innateness.
3. It is encapsulated.
4. It has a fixed neural architecture.
Cognitive neuropsychology systematically analyses the effects of brain damage on
cognitive functions, in particular by looking at the nature of the errors to test a certain theoretical
view, usually illustrated as a collection of sub-processes in the form of ‘boxes’ that are
connected to each other by lines or arrows (hence the term boxology).
Another popular research area for cognitive neuropsychologists was agnosia (an
inability to recognise objects).
Marr’s approach is based on serial processing- that is, the conversion of information
to a subsequent level of representation. Connectionist models are mainly descriptive rather than
explanatory. The neural-network approach showed that several assumptions, in particular
about the power of double association, were not tenable. A truly revolutionary development
was that of neuroimaging techniques. Using neuroimages, it is possible to get a better view on
the brain injury. As a result, greater attention has been devoted to psychological processed in
the brain and to areas of the brain that are active during certain processes, and less attention has
been given to the theory development in the field of cognitive processes.
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Chapter 3 | Neuropsychology: the scientific approach
Clinical neuropsychology is primarily concerned with the study of the effects of brain
disorders on behaviour, both in clinical practice and in scientific research. In clinical
neuropsychology, dissociation and double dissociation play an important role. Dissociation
demonstrates that the sub-processes are independent of each other, as each of them can be
disrupted separately. Usually, case studies or recovery studies are used for research. However,
these have drawbacks. Drawbacks of recovery studies include the test-retest effect, whereby if
one or more tests are used to establish a disorder following a brain injury, and the same tests
are used at a later date to measure recovery, a better score can be achieved the second time that
the patient takes the test(s)- not because the underlying function has recovered, but rather
because the patient is now familiar with the test(s).
Fields
In scientific research in the field of neuropsychology a distinction can be made between
fundamental neuropsychological research, which focuses on achieving a better understanding
of underlying cognitive disorders and the related brain structures, and clinically oriented
neuropsychological research, in which there is a greater focus on, for example, a more detailed
classification of symptoms, the usefulness of test instruments and procedures, and the follow-
up of the course of an illness.
Clinically oriented neuropsychological issues
In order to address symptoms, neuropsychologists undertake a neuropsychological
diagnostic assessment, carried out according to the empirical cycle, starting with a suitable
hypothesis. Then they collect data from the patient.
In the Stroop test (well-known in depression research), the naming of emotionally
loaded and neutral words or pictures is compared. This task is based on the principle of using
the power of a relatively automatic process.
This type of research has its limitations:
1) The main limitation of all psychological instruments is that the value of the conclusions
is largely dependent on the quality of the tests and questionnaires used.
2) A test battery, primarily because of logistical limitations that are often intrinsic to
research on patients, can contain only a limited number of tests, and it is often assumed
that a certain test for memory represents ‘memory’.
3) Missing values. If a test battery is not completed by a patient for whatever reason, there
will be missing values in the database. This causes problems with the analysis and
interpretation of the data.
Fundamental neuropsychological research issues
Scientific questions about the precise nature of a disorder and thus about the underlying
cognitive processes are generally studied using experimental paradigms. A classic example is
the study of spatial orientation by Posner. A cue is given preceding the stimulus. The cue can
be given in the centre or at the periphery of the visual field. The interval between the cue and
the target stimulus varies. Using these variations, Posner was able to demonstrate that the spatial
orientation process consists of several stages, namely disengaging attention from what it is
focused on at the moment, shifting attention, and finally returning attention. This is called
Posner’s diagram.
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