Distinctive features of unilateral spatial agnosia in right and left brain-damaged patients

In order to study the distinctive features of unilateral spatial agnosia shown by right and left brain-damaged patients, a test of copying drawings with guiding landmarks was given to 83 control subjects and to 248 patients affected by right (n = 108) or left (n = 140) hemispheric damage. The test enabled us to obtain a quantitative assessment both of the lines omitted ('omissions') and of the lines wrongly traced ('errors') on the half page contralateral to the damaged hemisphere. Results showed that contralaterally to the hemispheric locus of lesion a clear-cut double dissociation can be found between right and left brain-damaged patients: the former showed a striking tendency to omit the lines lying on the left half of the sheet, whereas the latter tended mainly to trace faulty lines on the right half of the drawings.

A neurolinguistic model for the study of aphasia

After having briefly discussed some of the most important models that are now used to understand or to classify the aphasic troubles, the authors explain the neurolinguistic model they are actually using to study some aspects of aphasics' verbal and nonverbal behavior. This theoretical model distinguishes proper linguistic from extralinguistic disturbances in the various clinical forms of aphasia. The existence in aphasia of extralinguistic components that might, in some way, influence verbal performances, is accepted by most authors. Much less obvious is the existence, at least in some clinical forms of aphasia, of proper linguistic (competence) disturbances. Our theoretical model assumes that in most clinical forms of aphasia some impairment of the semantic (lexical) structures of language exists, and it maintains that this trouble can be found both at the expressive and at the receptive level, both in verbal and in nonverbal tasks. Th results of some experimental investigations which give some support to this theoretical model, are briefly discussed.

[Verbal and non-verbal aspects of semantic disintegration in aphasia (author's transl)]

After a review of the explanations offered in the literature on the nature of aphasic disintegration, the author suggests that a nuclear impairment of semantic level of language integration may exist in many forms of aphasia. This hypothesis is supported by personal observations on verbal and non-verbal aspects of semantic impairment in aphasia. The incidence of semantic troubles is very high both at the level of verbal production and comprehension and at a non-verbal study of the "areas of meaning". No relationship was found between the incidence of semantic troubles and the ("fluent" or "non-fluent") clinical form of aphasia. A definite relationship exists between production of semantic paraphasias at the expressive level and number of semantic errors obtained as a verbal comprehension task, and between verbal semantic disorders and pathological performances at the non-verbal task of "semantic relationships".

[Elementary logic and semantic fields in aphasia]

Modern linguistics, like genetic psychology, postulate a non-linguistic basis for the structurisation of the semantic fields. If such is the case, it should be possible to observe in aphasia, where semantic deficiency predominates, a related disturbance in the semantic fields and logic. Paraxodically, such disturbances have been observed both in Broca's aphasia and in the predominantly semantic aphasia of Wernicke. A qualitative analysis shows that quantitatively identical results in the semantic aphasias of Broca and Wernicke are the result of phenomenological convergence. The related disturbance in the semantic fields and logic appears characteristic of the semantic deficiency which, in aphasic semiology, is marked by the substitution of one word for another. These finding support the theory of the relative autonomy of phonemic and semantic disorders in Wernicke's aphasia. They confirm the linguistic and genetic theory that the structure of vocabulatory is based on extralinguistic factors. They do not however provide an explantation for semantic disorders in aphasia. Further research is required to discover on what functional system articulation of the symbolic function and general operative capacity is based.

[An experimental study of autotopagnosia (author's transl)]

One hundred and twenty patients with unilateral cerebral hemisphere damage (54 aphasics, 21 non-aphasic left and 45 right brain-damaged patients and 57 control subjects without cerebral lesions were given a battery of verbal and non-verbal tests of autotopagnosia, with the aim of studying the relationships between disorders of body schema and the side of the hemispheric lesion. A second aspect of our research consisted in understanding whether impairment in naming and pointing to body parts following verbal commands was really a specific symptom or if the same difficulty was found when patients were asked to name or to point to parts of objects other than the human body. Our results have shown that: 1) the aphasic patients are significantly more impaired than the non-aphasic patients on all the tests, non-verbal as well as verbal; 2) when results obtained on tests of naming and of pointing to parts of the human body were matched with results obtained on tests of naming and of pointing to parts of objects other than the human body, no difference could be demonstrated. These findings suggest that autotopagnosia is a nonspecific symptom, and that it does not find a satisfactory explanation in terms of "disorders of the body schema".

[Acoustic and semantic disturbances of comprehension in aphasia]

The authors carried out a verbal auditory comprehension test on 115 aphasic patients, 44 patients suffering from a left hemispheric lesion without aphasia and 120 normal subjects used as acontrol group. The test also revealed either disorders in acoustico-phonemic discrimination or difficulities in semantic differentiation. The main aim of the research was to check experimentally the theory propounded by Alajouanine and colleagues (1964) according to which, in Wernicke's aphasia, it is possible to demonstrate a twofold correlation between disorders of comprehension and speech disorders both phonemic and semantic. Only one part of the theory of Alajouanine and colleagues has been confirmed by our experiments for our results have shown that there is a very close correlation between semantic paraphasias and disorders of semantic differentiation whilst no correlation can be found between phonemic paraphasias and disturbances in auditory phonemic discrimination.

[Homolateral and controlateral disturbances in the tactile discrimination of the hemispheric lesions]

Ten normal controls and 45 brain-damaged patients, affected by lesions of the right (N = 25) or of the left (N = 20) hemisphere were given a test of two points discrimination, in order to check the hypothesis of a different organization of the somesthetic function at the level of the dominant and of the minor hemisphere. Somatosensory thresholds were measured at the level of the back of the hands and of the back of the feet by means of a modified version of the Weber two-point aesthesiometer. When patients with lesions of the right and of the left hemisphere were compared the following results were obtained: --somatosensory thresholds were higher on the contralateral than on the ipsilateral side of the body in both groups of patients; --ipsilateral defects were found in about 20% of the brain-damaged patients, but no relationship was put in evidence between laterality of lesion and ipsilateral sensory defects.

Pattern of ipsilateral clinical extinction in brain-damaged patients

A test of double tactile simultaneous stimulation was given to 212 patients affected by focal (178) or diffuse (34) cerebral lesions to study the order of dominance between face, hand, and foot. Both in focal and in diffuse brain-damaged patients, a striking dominance of the face over the hand and foot was found. No significant difference between hand and foot was seen, but a mild prevalence of the foot over the hand was suggested by a cumulative analysis of our results. These findings do not support the hypothesis of a continuous downward gradient of dominance from rostral to caudal regions of the body.

Confabulation of denial in senile dementia. An experimental study

Some forms of confabulation ('confabulation of denial') seem due to the need to deny demential dissolution by replacing information pointing to illness with expressions suggesting normal health and efficiency. Seventy-six unselected patients affected by senile dementia were investigated in order to study the relationships between confabulation of denial and (a) stage attained by the demential process; (b) degree of memory loss, and (c) personality features and cultural models of the patients. Confabulations of denial were absent in the initial and the most advanced stages of dementia, whereas they frequently occurred in the stages of state and of evolution of illness. Memory loss did not seem to be directly responsible of the symptom, while personality features and social cultural models seemed to have a definite valence in the development of confabulation of denial. Some implications of these findings are discussed.

The unilateral forms of finger agnosia. An experimental study

The unilateral forms of finger ‘agnosia’ (UFA) were studied in 60 control and in 176 brain-damaged patients by means of a non-verbal test of finger localization. Both right and left brain-damaged patients showed a prevalence of finger agnosia on the hand contralateral to the damaged hemisphere, but this prevalence was significantly more important in the right hemispheric group. When the task performed was under visual control, the prevalence of UFA among the right brain-damaged patients seemed due mostly to unilateral spatial neglect, but this interpretation could not account for the results obtained with the hands hidden from view. Some implications of these findings are discussed.

Qualitative analysis of unilateral spatial neglect in relation to laterality of cerebral lesions

Two unselected groups of patients, affected by a mono-hemispheric cerebral lesion, were studied in two seperate services by means of various tasks of copying drawings, in order to check the hypothesis of a qualitative difference between unilateral spatial neglect (USN) of right and left brain-damaged patients. In both experimental groups drawing asymmetries were found to be of slight importance among the left hemispheric patients, consisting chiefly in a tendency to omit some figures lying on the right half of the models, and to be definitely more severe in the right braindamaged patients, where the main pattern of USN seemed to be the tendency to leave unfinished the left half of the drawings. A second aim of the study was to describe some less frequent features of USN, sometimes found in patients who were recovering from a severe damage of the minor hemisphere. These patterns of USN seemed to suggest that the core of unilateral spatial neglect consists in a peculiar disorganization of the type of synthesis of the sensory data which seems characteristic of the minor hemisphere.