Handbook Of Clinical And Experimental Neuropsychology

Gianfranco Denes, Luigi Pizzamiglio, Gianfranco Denes, Luigi Pizzamiglio

• Editorial: Psychology Press
• Año: 2020
• ISBN:
  9781317735014
• Edición: 1
• Categoría: Psychologie
• Categoría: Geschichte & Theorie in der Psychologie

The domain of neuroscience has had one of the most explosive growths in recent decades: within this development there has been a remarkable and renewed interest in the study of the relations between behaviour and the central nervous system. Part of this new attention is connected with the contribution of new technologies (PET, fMRI) permitting more precise mapping of neural structures responsible for cognitive functions and the development of new theoretical models of mental activities.
The diffusion of new pathologies (for example the pattern of cognitive impairment associated with AIDS) has further enlarged the field of clinical neuropsychology. Finally there has been an expanding clinical interest in the understanding and management of age-related cognitive changes.
This volume is the translated and updated version of the second edition of Manuale di Neuropsicologia (Zanichelli, 1996), by the same authors, and it reflects the current status of the art. It is intended to blend clinical and theoretical aspects of neuropsychology. The first part discusses the instrumental and clinical methods of investigation in neuropsychology, together with their development. A long section is dedicated to the language and memory disorders. The impairment of non-verbal cognitve functions, such as the disorders of space orientation, of of visuo-perceptive abilities, and of the emotions and attention, are extensively discussed. The pattern of degenerative dementias is thorougly described, as e is thoroughly described, as well as a number of new topics, such as a neuropsychological approach to consciousness. Finally, perspectives for treatment of some cognitive disorders are outlined.

Part I

Methodological Problems in Neuropsychology

1

Neuropsychology: Introductory Concepts

Giacomo Rizzolatti and Luigi Pizzamiglio

Although the historical priority of an idea or of a theory is always debatable, it is generally accepted that the first coherent conception of human and animal behaviour expressed in neurological terms was the Cartesian one. Figure 1.1 shows a graphic representation of the Cartesian conception. The nervous system is subdivided into two basic levels: a lower level, which can be assimilated in anatomical terms in the spinal cord and the brain stem, and an upper level, corresponding to the brain. Sensory information arrives at both levels. At the lower level it activates circuits, so that the organism responds to sensory stimuli with motor responses. This lower level is the level of reflexes. The sensory information that arrives in the brain is also transformed into motor commands. However, the sensorimotor transformation is not mechanical, as it is in the lower level, but occurs through the action of the mind. The latter creates a representation of the external world, stores sensations in the form of memories and decides how to act in the external world.

FIGURE 1.1

The Cartesian model of the central nervous system

Neuropsychology is the discipline that studies the processes belonging to the mental level in the Cartesian schemata through experimental means. Therefore, it deals with one of the oldest and most basic scientific and philosophical problems: the relationship between mind and brain. The means used by neuropsychology to tackle the problem are not, however, the deductive ones of philosophy but those of the experimental sciences. Neuropsychology is an eminently interdisciplinary science, converging with neurology, neuroanatomy, neurophysiology, neurochemistry, psychology, linguistics, and artificial intelligence.

It is difficult to say exactly when neuropsychology began. However, the Cartesian model posed the following problem for the first time with the clarity necessary for its verification and “falsification”. The brain is the site of the mind. However, it is also the point of arrival for sensory information and the point of departure for voluntary motor commands. Is it possible to conceive of the brain as a homogeneous structure, or does the dichotomy between neurological and psychic functions imply an anatomo-functional inhomogeneity? Given that there are receptive cortical areas and other efferent ones, is the remaining part of the brain homogeneous or can it be separated into areas with different functions? A scientifically satisfactory answer to this question was given in the second half of the nineteenth century.

The period extending from 1860 to 1900 is the period of the great neurological and neuro-physiological discoveries. The empirical and conceptual bases of neuropsychology were laid down during these 40 years. Broca’s studies (1861a, 1863, 1865) showed that a correlation exists between language motor disorders and lesions of the left frontal regions. Wernicke (1874) localised sensory aphasia in the posterior part of the superior left temporal gyrus and provided a systematic picture of the aphasias. Development of Wernicke’s concepts brought Lichtheim (1885) to propose the anatomo-functional schema of language centres, which has constituted the base of classification of the aphasias up to the present time.

In 1870 Fritsch and Hitzig demonstrated that electrical stimulation of an area in the frontal lobe produces isolated movements of contralateral limbs in the dog. This zone—the motor area—was soon defined in other mammals, including humans. The discovery of the motor area and the facility with which the experiment was replicated definitively defeated the antilocalisationist positions (Flourens, 1823) and opened the era of the electrophysiological study of the cerebral cortex in animals and in humans. Ferrier (1876) demonstrated the existence of motor areas in the monkey and suggested that the parietal lobe has visual functions. Münk (1878) established that the visual functions are primarily localised in the occipital lobe. Wernicke (1895) demonstrated that the somatosensory and somatoperceptual functions are localised in the parietal lobe. Bianchi (1895) described the spatial hemineglect syndrome in monkeys and suggested that the frontal lobe is involved in processes of memory and learning. The century closed with Liepmann’s (1900a) description of various types of apraxia and the possible neuronal circuits underlying voluntary movements.

The years stretching from the beginning of the 1900s to the end of the Second World War were less fruitful in terms of results than the preceding era. New discoveries were made, better descriptions and better localisation of syndromes were obtained, and the limits of the concept of localisation were debated, but the questions posed by researchers did not seem radically different from those posed at the end of the 1800s.

Various factors concurred during this period of conceptual stagnation in neuropsychological research. The first was the success of the preceding era. Results of experiments on animals and clinical observation had shown that the brain was basically organised in a way rather similar to the nervous centres forming the lower level of the Cartesian model (spinal cord, brain stem). Also, in the cerebral cortex there were sensory areas, motor areas, and intermediate areas (associative) linking the sensory and motor areas. Why should the function of these circuits be described with concepts such as mind, attention, consciousness? A neurophysiological explanation could and should be sufficient.

This point of view was reinforced by Pavlov’s (1927) experiments in Russia and Thorndike’s (1932) and Watson’s (1914) in the United States. If a slightly acid solution is placed in the mouth of a dog, it salivates. The response to the stimulus is a pure physical fact, so no mental explanation seems necessary. Now, if a sound is associated with the administration of the slightly acid solution, the animal will salivate when it hears the sound before, or also in the absence of, the administration of the solution. The response to the sound (conditioned response) follows precise laws as does the natural (unconditioned) reflex. Therefore, it is not logical to postulate two independent explanation systems for such similar phenomena.

The turning point reached by psychology through the learning experiments freed it (and neuropsychology as well) from many of its problems. If attention does not exist, but is simply a verbal description of certain behaviours, there is no sense in studying it, at least in neuropsychological terms. If there is no mental process during learning, and a certain nervous pathway is simply “reinforced”, the only real problem is that of localising the pathway or pathways involved in learning. Pavlov did not deny the dichotomy between the brain and the lower centres. According to his conception, learning is a specific function of the cerebral cortex. Therefore, the dichotomy between the brain and lower levels was accepted but was then resolved in terms of innate connections and learned connections. The Cartesian schema in Fig. 1.1 was substituted by that in Fig. 1.2. Once this schema is accepted, the task of the neuropsychologist is no longer that of explaining mental functions, which do not exist, but of localising the areas in which the associations responsible for the various behaviours occur.

FIGURE 1.2

The Behaviouristic model of the central nervous system.

The strongly antimentalistic intellectual climate that characterised the first 40 years of this century changed progressively and radically after the war. The works of Hebb (1949) and Broadbent (1958) reinstated and gave scientific dignity to terms such as attention and “set” (predisposition to respond in a certain way). Moruzzi and Magoun’s (1949) experiments demonstrated that a precise neuronal substrate exists for attention, at least in its intensive dimension. Sperry’s (1976) experimental results and theories brought the concept of consciousness to the fore. The brain-mind problem reappeared, and solutions that implied a brain-mind interaction were proposed both in a materialistic (Sperry, 1976) and spiritualistic (Eccles, 1986) vein. In a decade, more or less coinciding with the 1970s, psychology was transformed from behaviourism to cognitivism. The development of machines that showed intelligent behaviour changed the way of tackling the study of brain functioning, passing from a passive attitude of observation to an active one of builders of robots with “mental” faculties. Modern neuropsychology was born from the contribution of these new ideological tendencies and new scientific knowledge.

Besides the ideological factors, which created a favourable situation for the development of neuropsychology, a series of factors linked to the progress of neighbouring disciplines favoured its growth. Progress in neurosurgery and new radiological and brain imaging methods permitted anatomo-clinical correlations that were inconceivable only 10 years before. New neuro-physiological techniques made it possible to study neurone activity in nonanaesthetised animals with freedom of movement during the execution of complex tasks. Psychology offered methods and models of a complexity incomparable to the simple models borrowed from nineteenth-century psychology. Making use of these advances, neuropsychology assumed its individuality and independence, which increasingly separated it from clinical neurology. The term neuropsychology (Bruce, 1985), introduced in the 1950s, substituted the term brain pathology (Kleist, 1934a) or study of the higher nervous functions (Pavlov, 1927) and marked the birth of a new discipline, which was autonomous with regard to techniques and problems.

A chronological description of recent neuropsychological discoveries is beyond the scope of this chapter. A brief history of neuropsychology, subdivided into its basic sections—cerebral localisation, hemispheric dominance, memory, aphasia, agnostic disorders—has been published by Benton (1988). The reader can find essential information there. However, there are two interesting examples of how the various disciplines forming modern neuropsychology concur in the study of a neuropsychological problem. An example of the multidisciplinarity of the neuropsychological approach, which has relevance for the brain-mind problem, is that of neglect. A second example is the problem of hemispheric dominance.

Neglect is a disorder characterised by the inability to perceive and respond to stimuli presented in a particular area of space. The presence of neglect, at least in its most serious forms, can be determined by observing the patient’s behaviour in carrying out normal activities. The patient appears to ignore the space contralateral to the lesion. If the physician speaks to the patient from this side he or she does not respond or look towards where the voice of the physician is coming from, turning around to the opposite side. Often, when eating, patients, take food from only half of the plate. If they have to make a drawing, they execute only the part ipsilateral to the lesion. Neglect can affect not only extrapersonal but also personal space. For example, patients can forget to wash the part of their body contralateral to the lesion, or forget to shave half of their face. They can forget to dress the half of their body contralateral to the lesion. Finally, even when they have no motor deficits, patients do not explore the space opposite to the lesion either with their eyes or by turning their head. More rarely there can be partial or total absence of contralesional limb movements in the absence of paralysis. For a complete description of the neglect syndrome see Bisiach’s chapter in this volume.

What problems are posed by neglect? The first, common to all neurological syndromes, is the site of the lesion. This problem can be divided into two parts, one anatomical and one functional. Is the syndrome due to hypofunctioning or to nonfunctioning of the anatomically lesioned nervous tissue or to an alteration of other centres connected with it? In lower-level neurological syndromes, the anatomical explanation coincides with the functional one. For example, a lesion that causes flaccid paralysis affects (with very rare exceptions) the spinal motoneurones or their extensions. The lesioned mechanism is the conduction of the nervous impulses from spinal centres to the muscle. The situation is different when the lesion involves the higher nervous centres. In the case of neglect in humans, even if various cortical areas can be affected, the most frequent lesion is that of the right parietal lobe. How can this observation be explained? There are various possibilities. The first is that the neuronal substrate whose destruction produces the syndrome is in the right parietal lobe. This explanation seems to be the simplest and the most immediate. However, it is not necessarily true. In fact, it is possible that the information that is indispensable for awareness of contralateral space (lesioned in neglect) passes through the parietal lobe, but is used by other structures in the frontal lobe, in the cingulate gyrus, or even in the subcortical centres. In this case, the syndrome is due to a disconnection of the centres really responsible for the functioning of those that provide lower-order information necessary for obtaining this awareness. A third possible explanation is that the lost function in neglect does not result from the activity of a centre, but of an entire circuit, of which the parietal lobe is part.

It is obvious that postmortem techniques and traditional radiological methods cannot answer these questions. They can only localise the site of the anatomical damage. The problem of functional localisation of the deficit will be clarified in the future when new methods of functional investigation of cerebral activity, based on measures of cerebral blood flow or on measures of cerebral metabolism, become more diffused and more precise. Naturally, attentive clinical observation should be added to this, with particular emphasis on atypical cases of neglect, which can p...