Theoretical and practical foundations of clinical neuropsychology

One of the most important theoretical premises of neuropsychology is the understanding of mental function as a functional system consisting of hierarchically interconnected links. In this case, the links that are invariant to the functional system of its role (goal, result) and variable (operations, means of achieving a result corresponding to the goal) are distinguished. Such an approach allowed to formulate A.R. Luria concept of cerebral systemic dynamic localization of functions, the main provisions of which are as follows. Every mental function is provided by the joint integrative work of different brain zones, each of which makes its own specific contribution to the implementation of a certain link in the composition of the functional system. In accordance with the hierarchical structure of the function, certain structures of the brain have different meanings for the maintenance of mental processes. In this regard, the abnormal functioning of individual parts of the brain can lead to a more or less significant deficit in mental processes, affecting various levels and links in their provision. When implementing a particular type of mental activity, it does not always include all the structural units of the brain associated with an exhaustive representation of mental processes. Depending on the degree of formation, interiorization or automation of the function, the number of required afferent and efferent links is "curtailed" both in its external deployment and in relation to the brain zones that provide them. The concept of systemic dynamic localization of functions implies a kind of “intersection” between them in those links that are common to various types of mental activity.
A number of consequences follow from these provisions, which are the basis of neuropsychological diagnostics and are significant for clinical neuropsychology. Changes in the brain usually lead to a violation of only certain brain areas or the interaction between them, and therefore the mental process suffers not globally, but selectively, within its various components. It is essential to emphasize that in this case there remain intact links provided by the work of intact brain zones or systems. Naturally, this results in the restructuring of the entire mental process, and the degree of deficiency is determined by the role of the affected link in the integral system of mental function. Indicators of such a restructuring function can be its expanded, manual execution, the transition from an involuntary implementation level to an arbitrary, dissociation between the safe execution of tasks at an involuntary level with the inaccessibility or difficulty of the voluntary implementation of activities. This also includes such manifestations as the preservation of the execution of an action in one modality and a violation in another, a slowdown or unevenness of the pace of activity, latency of inclusion in it, sensitivity of mental functions to the conditions of their implementation (noise, interference, simultaneous load on several mental processes).
However, since, as mentioned above, various mental functions contain common links in their structure, the loss of one of them, as a rule, can lead to a violation of the “set” of mental processes with the defeat of one particular brain region, ensuring the implementation of this common component . On these main consequences of the theory of systemic dynamic localization of mental functions, the method of syndromic analysis of their disorders in local brain lesions is based. The concept of this method presents three basic concepts of clinical neuropsychology: factor, syndrome and symptom.
The most complex and to date not fully established is the concept of "factor", aimed at overcoming psychophysical parallelism and bearing in itself both physiological and psychological content. On the one hand, the factor is a certain type of analytical-synthetic activity of specific, differentiated, defined brain zones. In this sense, the factor acts as a result of brain activity. On the other hand, the factor is, as it were, introduced into the structure of mental functions; having a specific character reflecting the functional ambiguity of the brain zones, it provides the realization of one of the links of the functional system and, as a result, is presented in it as a psychological component.
It can be said that with the help of a factor a correspondence is established between the two main determinants of mental reflection: that which is reflected from the external and internal environment, and how it is carried out in specific forms of activity of the brain zones. Since in this context the concept of "factor" is one of the fundamental, let us turn to an example.
It is known that a person lives and acts in a spatially organized external and internal environment. The reflection of this property - the properties of the spatial organization of the world - is necessary for many types of activity (distance estimation, implementation of movements, solution of constructive problems, understanding of the digit structure of numbers, evaluation of spatial distinctive signs of letters, ideas about the scheme of one’s own body, etc.). This property finds its representation in speech in the form of the words "above", "under", "right", "left"; comparative designs; inverted sentences and cases ("brother of father" - "father of brother"). Finally, there are ideas about the "quasi-spatial" organization of a person's lexical experience, storing in memory a system of meanings of words in the form of "trees", "nests", and "semantic fields".
It is also known that with the defeat of the temporal-parietal-occipital region (TPO), the possibility of operating with spatially oriented objects is impaired. On this basis, it can be stated that the TPO zone provides a factor of spatial and quasi-spatial analysis and synthesis in mental activity.
Another example. Reflection of the world, its picture can be in various cases built on the basis of the analysis of stimuli that come in either in a temporal sequence (successively) or at the same time (simultaneously). Despite the fact that both of these methods in an individual experience exist in interaction, it is possible to identify activities that are associated mainly with one of them. So, the auditory perception of speech is a successive process, and the visual perception of objects is simultaneous. It is shown that the simultaneous organization of mental processes as a whole suffers from a lesion of the right hemisphere of the brain, and the successive - of the left. In this case, there is reason to talk about the factors of simultaneity and succession, as specific for the right and left hemispheres of the brain, respectively.
Both of these examples show the complexity and diversity of the manifestations of factors, the possibility of their assignment to larger or fractional structural and functional units of the brain. The existing data allow us to identify a number of factors that are “attached” to the work of various areas of the brain at various levels of its horizontal and vertical organization.
The syndrome is defined as a combined, complex impairment of mental functions that occurs when certain areas of the brain are affected and naturally due to the removal of a factor from normal operation. In particular, it follows from the example above that when a TPO area is affected, visual-spatial perception, speech, praxis, visual-effective thinking, counting operations and other processes that require spatial analysis and synthesis must be disrupted. It is this picture of mental impairment in this localization of the pathological focus that is shown by clinical observations. It is important to note that the violation of the spatial factor naturally unites the disorders of various mental functions that are internally related. In this sense, the violation of a factor is a syndrome-forming radical that forms the structure of the syndrome. The concept of “symptom” is no less closely related to the concept of “factor” than the syndrome. As a rule, it is used in two senses, corresponding to the stages of the procedure of neuropsychological examination of the patient. At the first stage of preliminary orientation in the general condition of the patient's mental functions, the manifestation of their insufficiency in the form of speech disorders, movement disorders, etc. is established. In this sense, a symptom is an external manifestation of functional deficiency. Considering the above about the multi-element structure of the function, it should be noted that at this stage of the study, the symptom of manifestation of mental function deficiency is multivalued, that is, it may indicate a wide area of ​​brain damage and is not a differentiated criterion of the topic of the lesion. At the next stage, a purposeful study of the symptoms, their neuropsychological qualification with the establishment of the disturbed factor underlying the formation of the symptom and giving it a “local” meaning is carried out.
Summarizing the overall relationship between the concepts of symptom, syndrome and factor, it can be determined that the neuropsychological syndrome is a regular, typical combination of symptoms based on the violation of a factor caused by a deficiency in certain brain areas in the case of local brain lesions or a certain type of brain dysfunction caused by another, non-local pathology. The main goal of the neuropsychological diagnostic examination is to establish a regular combination of neuropsychological symptoms based on the definition of the syndrome-forming disturbed factor.
Often, the concept of "factor" applies not only to the psychological and psycho-physiological characteristics of the syndrome, but also to clinical determinants of the state of mental functions due to the presence of cerebral and local symptoms in various brain pathologies. In our opinion, such an extensive interpretation of the factor is erroneous. However, it was precisely because of this that the dichotomy of factors on the general cerebral and local, directly due to the clinical characteristics of the pathological process, arose. It is known that in addition to local effects on the brain, a tumor can lead to a disturbance of liquorodynamics and the formation of a hypertensive syndrome, to introduce a toxic component in the clinical course of the disease, resulting in swelling and brain swelling. At the same time, the disruption of the normal course of mental processes is also caused by the topics of focal brain damage, and general changes in the brain's work, the consequences of which can be such pathological phenomena as the patient’s workload, slowing down of all types of activity, exhaustion, reduction in the rate of failure to complete the program negative attitude to the survey. Such a change in the background components of the patient's mental activity, incorrectly called cerebral factors, must be taken into account when working with the patient and when interpreting the data on the specific violation of individual mental functions obtained during the examination. The serious condition of the patient, caused by cerebral changes, is an indication for the dosed examination, the introduction of interruptions; It is often necessary to examine such a patient for several time-limited sessions in order to minimize the effect of background changes in mental activity in general on the performance of individual actions and operations.
Data on the general condition of the patient, the psychologist receives with careful familiarization with the history of his illness. In the neuropsychological practice of the school of A.R. Luria analysis of the history of the disease is given a special place. A preliminary study of the history of the objective data contained in the history of the disease, gives a lot of information needed to conduct a neuropsychological diagnosis. The time of onset of the disease, the appearance of the first symptoms of impaired mental functions, their specificity, the etiology of the pathological process (tumor, vascular pathology, trauma, inflammation) are very important for planning a neuropsychological examination. According to an objective history, the psychologist receives information about the state of the visual function. Equally important are objective information about the motor (the presence of paresis and paralysis, hyperkinesis), auditory and general sensitive areas. In addition to direct indications of the lateralization and localization of the lesion, these data impose requirements on the organization of the neuropsychological examination and the choice of methods adequate to the state of the motor and receptor systems.
Of particular importance in the study of objective information about the disease are data obtained from such procedures as craniography, arteriography, computed tomography, which directly indicate the nature of the pathological process and its localization in the right or left hemispheres, in convexital or deep, medial or basal parts. This determines the tactics of neuropsychological examination in the direction of a more thorough approach to identifying those symptoms that are characteristic of syndromes associated with an objectively verified lesion of a given brain area.
The tactical tasks of building a neuropsychological examination include the selection of more or less sensitized samples, and sometimes the creation of special sensitized conditions. Methods for sensitizing experimental conditions and individual methods include an increase in the rate of supply of incentives and instructions, an increase in the volume of stimulus material, and the presentation of the latter in noisy conditions. A more sensitized condition is to apply to the work of the analyzers not at the gnostic, but at the mnestic level (with the preserved gnosis, the function can detect a deficiency in memorizing patients with model-specific information).
It must be emphasized that any examination of a patient according to clinical indications should be gentle to him. In this sense, not every patient should and can go through a full and thorough study of all mental functions. The selection of methods, the choice of symptoms of mental disorders for their subsequent psychological qualification is largely determined, as mentioned earlier, by data from an objective history.
Speaking about the tasks of clinical psychology in the context of solving diagnostic issues, it should be noted that their spectrum, especially at the current level of development of medicine, is much broader than only the differential diagnosis of the topic of local brain pathology. The clinical practice included such objective methods for assessing the localization of the pathological focus as angiography and computed tomography in its various variants. The tasks of the actual topical diagnosis still remain in the field of clinical neuropsychology. In particular, dysfunction of the brain systems does not always coincide with the localization of the lesion of the brain. In some cases, a foci verified by contrast and radiographic techniques reveals itself with neuropsychological symptoms not only at the place of its localization, but also at "nearby" symptoms, indicating a change in the functional state of the structures adjacent to the localized lesion zone and provides information about the possible direction of tumor growth.
In addition to solving issues related to the actual differential topical diagnosis, neuropsychological examination also has other diagnostic tasks. These include assessment of the state of mental functions in a patient during the process of pharmacological treatment of the brain and restoration of functions after a directed surgery. In some cases, information about the neuropsychological syndrome gives reason to choose the tactics of operational impact on the brain structure. For example, the study of the neuropsychological syndromes of the lesions of the corpus callosum in its various sections contributed to the development of the tactics of the transcollosal approach to the removal of basal brain tumors. Of particular importance for the nature of surgical intervention is the neuropsychological syndrome with a compensated state of mental processes and in cases of an established topical diagnosis using objective methods. We are talking about focal brain lesions, giving minimal neurological disorders in combination with the absence of visible disorders of mental functions.A thorough neuropsychological examination aimed at assessing the impairment of mental processes, which should occur when the brain damage is localized, allows you to set the degree of compensation and to give a forecast about the possible structure of the syndrome in cases of decompensating postoperative effects, its severity and the nature of reverse development. The sensitivity of the neuropsychological method to a possible change in the functional state of the brain as a whole and its individual systems makes it possible to describe the structure of the syndrome of impaired mental functions, not only in the dynamics of the actual local brain pathology.
The findings of recent years related to the study of the selective influence of various drugs on brain structures and, accordingly, on various components of mental processes (factors), are getting more and more clinical use of brain dysfunctions. The correct use of these drugs requires not only knowledge of which structural and functional areas of the brain they can have a therapeutic effect. Directed pharmacological effects in this case are possible with an understanding of the specifics of the mental defect, the neuropsychological syndrome and the disturbance of the factors underlying it. Only in this case it is possible to predict not only the direct effect of the drug, but also those restructuring in the psyche system that can occur in this case.
Thus, the tasks of a clinical neuropsychological examination of a patient can be combined into two interrelated classes: 1) differential topical diagnosis and 2) description of the structure of mental function disorders based on the syndrome component in order to indicate a violation of the factor (s) underlying their deficiency and functional rearrangements. The ability to solve the second class of problems provides the prospect of the neuropsychological clinical diagnosis going beyond the limits of the local brain pathology itself to a wide range of diseases, which result in mental disorders that require therapeutic action, corrective and rehabilitation measures.The generalization and understanding of the data obtained at the same time creates new prerequisites for the further development of ideas about the connection of mental processes with the brain substrate, i.e. for the development of theoretical neuropsychology in its dialectical unity with practice.