Qualitative hemispheric differences in semantic category matching.

A unilateral category matching task with words as stimuli was employed to investigate semantic processing in the right and left hemispheres (RH, LH). An overall right visual field (RVF)/LH dominance was observed and performances were better than chance, also in the left visual field (LVF)/RH. A qualitative analysis of reaction times with individual differences multidimensional scaling (INDSCAL) revealed that LVF/RH INDSCAL solutions were significantly more differentiated in structure than RVF/LH solutions in terms of number and size of dimensions. These findings support a depth of activation hypothesis of hemispheric processing, with the LH rapidly and focally and the RH slowly and diffusely activating the semantic network.

Adjusted hypervolemic hemodilution in acute ischemic stroke.

We prospectively randomized 47 patients with acute ischemic stroke of the middle cerebral artery of less than 24 hours' duration to either adjusted hypervolemic hemodilution or control treatment and followed them up for 90 days. Rapid hemodilution to a target hematocrit of 30-35% as monitored with bedside determinations was achieved by using infusions of dextran 40, venesections, and infusions of additional crystalloid solution when necessary. There was no difference in the death rate between the two treatment groups. Of these 47 patients, 37 (19 in the hemodilution group and 18 in the control group) could be followed up for the entire study period of 3 months. The relative improvement in neurologic function from day 1 to days 8, 21, and 90 was significantly better in the hemodilution group than in the control group. In accordance, special tests for fine motor control of the paretic arm disclosed better performance in the hemodilution group. The frequency of patients with severe disability was significantly lower in the hemodilution group on days 8 and 21. Plasma viscosity (measured in 11 patients) was not affected by infusions of dextran 40. Vigorous hypervolemic hemodilution in patients with acute ischemic stroke is well tolerated and improves early neurologic outcome with an effect lasting at least 3 months.

[Acute aphasia]. / Die akute Aphasie.

Acute aphasia is in most cases due to cerebrovascular disease. Its occurrence is a strong indication of a lesion in the language-dominant hemisphere, i.e. usually the left. Aphasia has to be differentiated from confusional states, mutism and dysarthria. We present the different aphasic syndromes, the clinical evaluation of patients with aphasia, the differential diagnosis and etiological considerations. Finally, therapeutic approaches to aphasia treatment are pointed out.

[The right cerebral hemisphere]. / Das rechte Hirn.

An attempt is made to delineate typical clinical syndromes in the light of four selected patients with lesions in different regions of the right hemisphere. For higher cortical functions of the right hemisphere, as in the rest of the central nervous system, the locus of the lesion is critical for the nature of the deficit. Comparisons of damage to homologous areas in the contralateral left hemisphere with those in the right suggest that the functions of the right hemisphere are not subordinate to those of the left but are complementary and work in coordination with dominant hemisphere functions. In addition to dominance for spatial functions, the tasks of the right hemisphere are to recognize, evaluate, and react to non-verbal signals such as emotions, facial expressions, gestures and intentional modulation of speech. Impairment of these functions after right hemisphere damage shows that such compromised behaviors can frequently lead to serious social consequences.

Is there parallel and independent hemispheric processing of intonational and phonetic components of dichotic speech stimuli?

The possibility of hemisphere interaction in the processing of spoken language was studied in two dichotic listening experiments. The stimulus material consisted of six CV syllable triplets each spoken with each one of six intonation contours. In Experiment I, 15 aphasic patients, 8 patients with unilateral right hemisphere lesions, and 10 normal controls were asked to identify the four components of a dichotic item from a multiple-choice (MC) set comprising all possible CV triplets and intonation contours. In Experiment II, 30 normal subjects were required to identify either the right or left ear stimulus alone from an MC set comprising the right and left ear stimulus together with the two wrong combinations of right ear CV triplet with left ear intonation and vice versa. It is concluded from the results that the left hemisphere is capable of processing both phonetic and intonational information and that there is neither the necessity nor the tendency for right hemisphere participation in the perception of spoken language.

Facet theory applied to the construction and validation of the Aachen Aphasia Test.

The linguistic performance of 120 aphasic patients of the four standard syndromes assessed by the Aachen Aphasia Test (AAT) is analyzed by a nonmetric (ordinal) multidimensional scaling procedure (Smallest Space Analysis, SSA1). The linguistic structure of the test items is characterized within the framework of L. Guttman's facet theory. Three systematic components (facets) are discerned: linguistic modality, unit, and regularity. Properties of the facets as well as their relations are assessed and tested empirically by analyzing the interrelations among different items or sets of items. The spatial configurations obtained by the scaling procedure fit only partially the expectations derived from the facet-theory model. The modality facet was found to have a strong overriding influence on the aphasic test performance. The facets unit and regularity were only found for the most rigorously designed subtests. Written Language and Comprehension. The results suggest the introduction of a new combined facet linguistic complexity which reflects the dependency of the facets regularity and unit.

To what extent are the cognitive performances of Wernicke's aphasics disturbed by their own vocalizations?

The influence of vocalization on performance in the Token Test and arithmetic and memory span tasks was studied in Wernicke's aphasics. Tasks had to be carried out under two conditions: performance with oral repetition of the task commands or oral description of the task stimuli; performance without oral repetition or description of task commands or stimuli. Performance was significantly better in all tasks when no vocalization was required. The results are taken as evidence that in Wernicke's aphasics any activation of impaired language functions leads to interference between the defective linguistic functions and those which are still available to the patients.

[Broca's aphasia. The clinical picture and a consideration of the neurolinguistic structure (author's transl)]. / Die Broca-Aphasie. Klinisches Bild und Uberlegungen zur neurolinguistischen Struktur.

Broca's aphasia is characterized by disorders on the phonemic, syntactic and lexical level of linguistic description. It is not only the patient's speech which is impaired; abilities to comprehend, read and write are likewise impaired. Articulatory disorders (dysarthria) which are due to an impaired innervation of the phonatory and articulatory musculature may exist. However these disorders do not account for all the linguistic deficits found in cases of Broca's aphasia. The characteristic feature enabling a differential diagnosis of Broca's aphasia is agrammatism.

[Global aphasia. The clinical picture and a consideration of the neurolinguistic structure (author's transl)]. / Die globale Aphasie. Klinisches Bild und Uberlegungen zur neurolinguistischen Struktur

Global aphasia is described as a unitary syndrome which is characterized by a severe impairment of all linguistic capabilities. Speech production is extremely limited and consists of stereotyped phrases, recurring utterances or a few isolated words which are usually neologistically distorted. The patients are unable to express their thoughts in a situationally adequate manner. Language comprehension is restricted to simple questions and commands. A clinical description of the syndrome is given and the neurolinguistic structure of the disorders is discussed.