Effect of visual complexity in tachistoscopic recognition of Kanji and Kana symbols by German subjects.

Kana and Kanji characters differing in figural complexity, as defined by the number of strokes, were presented tachistoscopically in the right and left visual field to 20 right-handed German subjects not familiar with Japanese script. Neither an interaction between complexity of script and visual field nor any simple main effect of visual field were obtained. It is concluded that the complexity of the different types of script is not critical for visual field asymmetries observed in experiments dealing with the recognition of Kana and Kanji in Japanese subjects.

Disorders of calculation in aphasic patients--spatial and verbal components.

The aim of the study is to investigate whether the disorders of calculation observed in patients with Broca's aphasia are due to linguistic factors whereas those observed in patients with Wernicke's aphasia may be reduced in part to a disorder in the ability of spatial visualization. Two sets of arithmetic tasks were given to 20 Broca's aphasics, 20 Wernicke's aphasics, 20 patients with right hemispheric retrorolandic cerebral lesions and 40 patients with no brain damage. The solution of the tasks required different degrees of spatial visualization. The statistical evaluation of the data showed, as hypothesized, that Wernicke's aphasics perform significantly poorer than Broca's aphasics in tasks with a more pronounced spatial component than in the tasks having a predominantly verbal component.

Transcranial Doppler ultrasonic assessment of middle cerebral artery blood flow velocity changes during verbal and visuospatial cognitive tasks.

Hemisphere specific changes of blood flow velocity in the right and left middle cerebral artery (MCA) induced by cognitive demands of verbal and nonverbal tasks were examined by means of a newly developed technique of simultaneous bilateral transcranial ultrasonic Doppler sonography (TCD). Thirty-one right-handed healthy volunteers served as subjects. Identical stimulus and response procedures were used with all tasks to avoid possible differential effects of these conditions on blood flow velocity. Compared to the preceding resting phase, the increase in flow velocity induced by each of the verbal tasks (sentence completion, similar or contrasting word meaning, similarities) proved to be significantly higher in the left than in the right MCA. Among the non-verbal visuospatial tasks only the "identical pictures" (perceptual speed) task led to a complementary higher increase in right MCA blood flow velocity. No such asymmetry in blood flow acceleration was observed, however, with the tasks "figure assembly" and "cube comparison" which require visualization and mental rotation of figures. The findings underline the recently emerging uncertainty in neuropsychological research with regard to the functional specialization of the right hemisphere.

Hemispheric asymmetry of arterial blood flow velocity changes during verbal and visuospatial tasks.

Changes in arterial blood flow velocity induced by cognitive activity were measured by simultaneous bilateral transcranial Doppler sonography (TCD) of the posterior and the middle cerebral artery. The finding of a robust left hemisphere dominance for verbal tasks but of an inconsistent right hemisphere dominance for visuospatial tasks obtained in an earlier study [13], in which TCD measurement had been restricted to the middle cerebral arteries, was confirmed. At the same time, it could be demonstrated that the failure to find the expected right hemisphere dominance for tasks of spatial visualization and mental rotation extended to the TCD measurement of the posterior cerebral arteries.

Effects of spatial arrangement of letter pairs in a name-matching task with unilateral and bilateral hemifield stimulation.

In tachistoscopic studies requiring "same/different" judgements on pairs of stimuli, differences between unilateral and bilateral presentation have been interpreted in terms of higher level cognitive processing. However, unilateral presentation is usually confounded with vertical and bilateral presentation with horizontal arrangement of stimuli. The effect of various stimulus arrangements was examined in two experiments. The results gave no evidence for an independent effect of uni- vs bilateral presentation, but rather a strong effect of the spatial arrangement such that pairs arranged on a straight line through the fixation point yield faster reaction times than any other vertical or horizontal arrangement.

Hemispheric dominance in the processing of J.S. Bach fugues: a transcranial Doppler sonography (TCD) study with musicians.

Although the majority of studies on musical processing in musicians observed a left hemisphere dominance which has usually been explained by a proficient analytical strategy used by these subjects, the findings are still inconsistent. Changes in hemispheric activity induced by listening to music (J. S. Bach fugues) and by recognizing the repetitions of the fugue theme were examined, using the technique of bilateral transcranial Doppler sonography (TCD) of the left and right middle cerebral artery (MCA). Subjects were 32 right-handed musicians, half of whom were members of an orchestra or members of a choir. The fugues were presented in two versions: a-cappella and instrumental. During passive listening to the a-cappella version, a weak left-dominant asymmetry of blood flow acceleration was observed, while there was no hemispheric asymmetry during listening to the instrumental version. During the task of fugue theme recognition, a highly significant asymmetry in favour of the right MCA was observed with both versions. It is concluded that when the processing of complex musical material has to be based on the analysis of melodic contour features and calls for working memory capacities a right hemisphere dominance is observed even in musically sophisticated subjects.

Diagnostic value of saccadic pursuit eye movement in screening for organic cerebral dysfunction.

In order to validate the results obtained in a preliminary investigation the saccadation of slow pursuit eye movements was examined in 19 patients with unilateral brain damage, in 25 patients with diffuse cerebral disease and in 26 neurotic patients. The diagnostic significance of saccadation was ascertained in detecting general cerebral dysfunction. By means of a discriminant function combining the parameters, "number" and "size", of saccades more than 80% of the brain-damaged patients and controls could be identified correctly, but the side of the cerebral lesion could not be determined.

Residual information processing in the neglected visual half-field.

A patient with neglect of visual half-field without hemianopia performed "same/different" interfield comparisons and named stimuli presented either unilaterally or bilaterally in the visual half-fields. With unilateral presentation he could name all stimuli in both fields, whereas with simultaneous bilateral stimulation his performance decreased to about 50% correct naming of left visual field (LVF) stimuli. This performance was not improved by cueing for the presence of LVF stimuli. Interfield comparisons were 100% correct in all conditions. It is concluded that inattention for the left hemispace in patients with visual neglect occurs whenever information in the right hemi-space attracts attention or must be consciously processed. Simple "same/different" judgements are presumably performed on a pre-attentional level and are not affected by neglect.

Influence of contextual complexity on the processing of cartoons by patients with unilateral lesions.

It was examined whether the performance of right hemisphere patients in the comprehension of cartoons is predominantly influenced by disturbed processing of affective material or by cognitive deficits. Cartoons differing in their cognitive demand were presented to groups of right hemisphere patients, aphasics and normal controls. Subjects were required to identify the cartoon in a multiple choice set of four pictures. Additionally, subjects were asked to rate the funniness on a three-point scale. The results indicate that the impairment of right hemisphere patients is caused by a combination of visuo-perceptive and cognitive deficits rather than by an inability to identify the affective component of cartoons.

Influence of figural complexity on the identification of Kanji and Kana characters.

Kana, simple Kanji, and complex Kanji characters differing in figural complexity (number of strokes) were tachistoscopically presented to the right and left visual half-fields of 115 German subjects. The subjects had to decide whether a stimulus (lasting 150 ms) was the same as or different from a sample stimulus (lasting 1000 ms) presented immediately before to the center of the visual field. An increased left field advantage in reaction time with higher figural complexity was hypothesized (Visual Field X Type of Script interaction). Analyses of variance, however, did not show this interaction. Because of a significant Type of Script X Response Type interaction simple main effects were calculated which were all significant. Pairwise comparisons for type of script were significant except for Kana vs. simple Kanji. No other significant effects were obtained. Reaction times were shortest for simple Kanji, intermediate for Kana and longest for complex Kanji. The results indicate that high figural complexity of Japanese characters does not favour the left visual field.

Hemispheric asymmetry in the recognition of emotional attitude conveyed by facial expression, prosody and propositional speech.

In this study 27 patients with right hemisphere lesions, 25 patients with left hemisphere lesions and 26 normal control subjects were investigated for unimodal and simultaneous multimodal recognition of emotional attitude. All subjects were shown 330 videotaped items of 4 seconds duration, each of which was to be judged in terms of facial expression, emotional prosody and the emotional meaning of the underlying spoken sentence. In a preceding experiment comparable unimodal emotional stimuli were applied. The results suggest (a) right hemisphere superiority for recognition of emotions conveyed by facial and prosodic information, (b) a right hemisphere dominance for the recognition of fear and (c) no significant enhancement of right hemisphere superiority under multimodal presentation of emotional stimuli.

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.

Sensorimotor learning in ideomotor apraxia.

Sensorimotor learning ability in patients with ideomotor apraxia was investigated, using as subjects, eight patients with ideomotor apraxia, 8 with aphasia without ideomotor apraxia, and 8 normal controls. The aphasia, apraxia, and normal control groups were matched for age, sex, and education. The aphasia and apraxia groups were chosen to control for lesion size and scores on Kimura's recurring figure test, the Token test, and intelligence. The mirror-aiming test was performed and the learning effect in terms of decreases in total time, the number of errors, and the times for errors were examined. There was no statistically significant difference between the learning effect of the apraxic group and that of the aphasic group for total time, the number of errors, and the times for errors; however, there were group differences on each trial for number of errors and the times for errors. These results suggest that patients with ideomotor apraxia have some difficulties in motor performance rather than disturbance of learning.

Comparison between visual half-field performance and cerebral blood flow changes as indicators of language dominance.

The determination of hemispheric language dominance (HLD) can be accomplished in two ways. One approach relies on hemispheric differences in cerebral blood flow velocity (CBFV) changes during language activity, while the other approach makes use of performance differences between the left and right visual field when verbal stimuli are presented in a tachistoscopic visual field paradigm. Since both methodologically different approaches claim to assess functional HLD, it seems plausible to expect that the respective laterality indices (LI) would correspond. To test this expectation we measured language lateralisation in 58 healthy right-handed, left-handed, and ambidextrous subjects with both approaches. CBFV changes were recorded with functional transcranial Doppler sonography (fTCD). We applied a lexical decision task with bilateral visual field presentation of abstract nouns and, in addition, a task of mental word generation. In the lexical decision task, a highly significant right visual field advantage was observed for number of correct responses and reaction times, while at the same time and contrary to expectation the increase of CBFV was significantly higher in the right than left hemisphere. During mental word generation, the acceleration of CBF was significantly higher in the left hemisphere. A comparison between individual LI derived from CBF measurement during mental word generation and from visual field performances in the lexical decision task showed a moderate correspondence in classifying the subjects' HLD. However, the correlation between the corresponding individual LI was surprisingly low and not significant. The results are discussed with regard to the issue of a limited reliability of behavioural LI on the one hand and the possibility of a fundamental difference between the behavioural and the physiological indicators of laterality on the other hand.

Kimura's Recurring-Figures-Test: a normative study.

Administered Kimura's Recurring-Figures-Test to 427 normal Ss from Germany. A Kuder-Richardson test reliability of rtt = .94 was obtained. T-scale norms are given for two subgroups of different educational level.