NEUROPSYCHOLOGY IN THE DIAGNOSTICS OF LOCAL BRAIN INJURIES

Prof. A.R. LURIA (Moscow)

During the last few decades a new branch of Psychology has grown -Neuropsychology-the application of psychological methods for the diagnostics of local brain injuries.

It is well known that the beginning of the study of localization of brain functions in the second half of the 19th century started with the analysis of aphasia, and that after brilliant studies of Broca and Wernicke it seemed, that the description of such symptoms as loss of motor speech, or the under- standing of spoken language can be used as a means for evaluation of the local diagnostics of brain injuries.

The heroic period of the development of neuropsychology which started with these studies lasted not too long.

From the beginning of this century a marked disappointment in a pos- sibility of a strict localization of complex psychological processes could be observed'. Neurological analysis made obvious that the distrubances of motor speech and understanding of language as well disturbances of writing and reading, complex symbolic movements and gnostic processes could be obser- ved in different lesions of the hemispheres and that all these disturbances are to be considered more as a dissolution of the most complex level of higher forms of nervous activity than as symptoms of an isolated cortical focus.

It seemed for a time that the hopes to use experimental psychology for a local diagnostics of brain lesion was impossible, and that neurology and neurosurgery have not to count on the help of more elaborated psychological methods for their practical diagnostic work.

But-as the history of scientific psychology proved-these pessimistic views were wrong, and when-after an intensive work of a generation-new approaches were elaborated and new data obtained,-it became clear that experimental psychology was able to give an invaluable help for the local diagnostics of brain lesions.

The use of psychological methods for the diagnostic of local brain lesions could become possible only after an intensive work: basic concepts of psycho- logical functions had to be revised and new methods of analysis had to be developed; that was the way for a success in this new field.

A few basic ideas which underly neuropsychological analysis of local brain lesions can be mentioned, and some illustrations of these concepts can be demonstrated.

Every psychological process-such as writing or reading, perception of an image or motor action-ean be understood only as very complicated func- tional systems. These systems are formed in the course of a complex social development and they have very complicated dynamic structures. They

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all have their afferent (or sensory) components. their motor organization ; they include different neurophysiological mechanisms providing special forms of analysis and synthesis of the information received, as well as mechanisms for matching of preliminary intentions with the effect of actions, which is an important part of the whole self-regulating behavior.

It is obvious that such a complex process can never be a product of an isolated group of nervous cells or a circumscribed cortical area, and is based on a complex system of different cortical zones.

A basic fact is decisive for neuropsychology: i t is that each of these zones, which constitutes a part of this functional system plays a specific role in the whole functional system and provides a specific factor in the psychological activities in question.

Circumscribed local lesions of the brain destroy this very specific com- ponent-a visual or visuo-spatial analysis, an acoustic or motor successive synthesis etc., and the whole functional system becomes disintegrated.

The most important is that in different lesions, with different factors disturbed, the type of this disintegration becomes different, and a careful descrip- tion of this disintegration can be used as a basic way towards a neuropsycho- logical analysis of the symptom and towards the evaluation of local focus underlying the whole injury.

This psychological qualification of the symptom is the heart of the neuro- psychological analysis of the local brain lesion.

We shall try to illustrate this approach only on one example.

*-* We shall choose for such an analysis the distrubances of writing; and we

shall try to show how different are those disturbances in different localisa- tions of brain injury, and how valuable can be a sophisticated neuropsycho- logical analysis for a local qualification of a symptom.

Writing is a very complicated process, and a whole complex of compo- nents is necessary to provide a normal writing of a word by dictation or spontaneously.

To write a word a careful acoustic analysis of the stream of the speech sounds i s necessary; if this acoustic analysis is insufficient-no writing (in our indo- european languages) is possible.

As it was shown by modern linguistics and by psychophysiology of lan- guage-this acoustic analysis of the speech sound is a complicated process. It has as a basis a differentiation of the acoustic stream in isolated units of speech sounds-phonemes, different in different languages, based on specific sound features and constituting specific phonetic groups. Only when such specific phonematic features are singled out as cues for perception-sounds become units of meaningful speech and can be perceived as components of meaningful words.

If such a sophisticated acoustic encoding is insufficient, phonemes can be perceived as undifferentiated noises or as slight deviations of the same sound.

It is well known that in German the length of the sound is decisive for a change of meaning: Stadt and Staat, Satt and Saat have different meanings in German language, and for a German listener these words sound vem diffe- rently; but for a Russian-whose language does not use the length of a sound as a cue for differentiation of meanings, these pairs of words sound very simi- lar. It is a hard task for a Russian to differentiate the English &wine’’ and “vine”, or a French-c&le” and <<lait”, but it is a very hard problem for an Englishman to grasp the difterence of softness in Russian words. The

same difficulties can be observed when a Russian as well as an Englishmen tries t o perceive the differences in a Chinese 6 (to buy) and ma (to sell), allthough for a Chinese these differences are very obvious.

This phonematic analysis of the speech sounds becomes possible only if the cortical mechanisms of the left temporal zone (acoustic or verbo-acoustic analyser) is preserved. As it was shown elsewhere disturbances of the upper posterior part of the left temporal zone result in an inability of acoustic differentiation of the speech sounds, and the understanding of meaningful speech becomes very difficult.

That is the basic mechanism of so called acoustic (or sensory) aphasia, and many symptoms of this clinical picture become clear if such an analysis is made.

But there is an important result of this disturbance: the patient with a lesion of the left temporal lobe looses his ability to write by dictation or spontaneously: he confuses such similar sounds as 16b” and “p”, c d ‘ ’ and tit", and in severe cases he confuses even more distinct sounds. That is why his writing becomes very poor, but a careful analysis can show that this dis- turbance is a result of a detective acoustic analysis and the confusion of the similar sounds, and cases when a patient writes &$gasha” instead Lskasha” (cereal), (6kora” instead “gora” (mountain) can be used as examples of such type of writing defects in cases of lesions of the left temporal zone of the cortex.

Acoustic analysis is important for evaluation of speech sounds and for writing but is not sufficient for those processes. As our experiments have shown,-- an additional kinesthetic analysis is necessary for this purpose, and it takes the shape of articulatory analysis of the speech sounds.

When a small child is beginning to write,-it is unable to write by dicta- tion without articulation of the sounds of the word. That is why (as i t was shown in our laboratory by L.K. ~ ‘ A Z A R O V A ) after the elimination of arti- culatory (or kinesthetic) analysis of the sounds the number of mistakes in writing of a child of the first or second grade-increased sixtimes. The impor- tant fact is that the cortical mechanism of this kinesthetic analysis of the speech sounds is very different from the acoustic analysis; it includes the activity of the lower parts of the postcentral (kinesthetic) cortex of the left hemisphere, -and when this part of the cortex is disturbed-precise articulation becomes impossible. In these cases similar articulemes are confused and the subject begins to pronounce <id’’ instead of -1” or Ccn’’, (linguo-palatal arti- culemes) and 6 m ” instead of ~6p” or ccb”, (labial articu1emes)-and a clinical picture of wfferent” or r<kinesthetic motor aphasia” can be observed.

I t is easy t o see that these defects play a decisive role for the disturbances of writing: the subject becomes unable to use precise articulatory analysis for evaluation of speech sounds and begins to confuse similar articulemes in his writing. Such examples as writing of “ston” or czstod” instead of ~ ~ s t o l ” (table), or “khanat” instead $rkhalat”--(coat) are symptoms of such a kind of writing disturbances. It is obvious that writing is disturbed in both cases -of temporal as well as in the cases of postcentral lesions, but in both cases the kind of writing disturbance is different.

The acoustic and kinesthetic analysis of the speech sounds are of basic importance for writing; but there are more factors included in the writing process.

To write a word-is to re-code the sounds (or phonomes) into letter (or graphemes) and for such rc-coding a still different cortical mechanism is necessary.

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I t is well known to neurologists, that a visual and visuo-spatial organi- zation necessary for the construction of graphemes is provided by occipital or parieto-occipital parts of the cortex. That is why in local lesions of these parts of the left hemisphere-the whole process of acoustic or kinesthetic analysis of the speech sounds remain undisturbed, but the spatial organiza- tion of graphemes becomes impossible.

There are the cases when the patient tries to write a letter but is unable to find the proper spatial orientation of its componants,-visual mistakes of mirror lines can be observed,- and the whole writing process is disturbed again,-this time in a thir, different form.

W’e can omit further examples and spare time to show how differently the writing is diaturbed in lesions of premotor zone, in lesions of the subcortical ganglia, or of frontal lobes. The really important fact is that in any of these lesions disturbances of writing have a different structure and can be analysed as symptoms of separate syndromes. In every case mentioned-psycholo- gical analysis is able to make an objective description of the structure of symptom-and to single out the primary defect underlying the whole dis- turbance.

All that has a great signijicance for the use the neuropsychological method for the erraluation of the symptom, for the analysis of the basic distuTbances,- and for the local interpretation of the symptom.

In using the esample of various forms of writing defects we tried to show the kind of approach of neuropsychology to the study of local brain injuries. It is easy to see that only a sophisticated psychological analysis of the stzucture of the symptom makes it possible to use such complex phenomenon as writing disturbances for a qualijication of the defect and for the local diagnostics of the disorder.

In the course of the last few decades a series of symptoms (disturbances of speech and reading, of perception and movement, of calculation and pro- blem solving were studied in our laboratory for the same purpose,-and as a result a neuropsychological analysis is now included in several important neurological and neurosurgical clinics of our country, and is used for the pract- ical purpose of local diagnostics of t he brain injuries.

It can be easily understood that the development of this new branch of applied psychology became possible only as a result of a careful revision of the basic psychological concepts and of new approach to the psychophysiolo- gical analysis of the basic psychological processes.

That is why neuropsychology is not only an important branch of applied psychology.

Its development is of high significance for the revision of the whole field of the general psychology itself,-and I can hope that a new scientific approach to the neurological basis of psychological processes will be a result of the development of this new and important discipline.

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