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Biomedical subjects

W Hartje

Publications and source records attributed to W Hartje.

At least 19 recordsLinked to original sources
PubMed1991

Short-term memory performance with magnetic stimulation of the motor cortex.

Whether transcranial magnetic stimulation of the motor cortex has an influence on memory was investigated. In a first experiment with 21 healthy volunteers six pronounceable nonsense words were visually presented, immediately followed by a magnetic stimulus. There were three blocks of stimulation with field intensities of 60, 80 and 100% (referring to a maximal intensity of 2 Tesla), each block comprising six magnetic stimuli and six nonsense words. After each block there was a free recall test and at the end another free recall trial as well as a multiple-choice recognition test for all 18 words. Eighteen subjects served as controls, undergoing the same procedure, except that the field intensity was zero. A significant but small reduction of short-term memory performance was observed only for 100% field intensity. In a second experiment with 16 subjects who had not participated in experiment I, the effect of 100% intensity cortical magnetic stimulation was compared with a control stimulation over the cervical spine. There was no difference in free recall or in the multiple-choice test between the sites of stimulation, suggesting that the difference in the 100% intensity block in experiment I was not due to a specific cortical effect of the magnetic field on memory function. With respect to the effect on memory functions, transcranial magnetic stimulation of the motor cortex is thought to be a safe method.

Adult↗
PubMed1988

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.

Adult↗
PubMed1988

Left hemispheric interference with nonverbal performance in aphasics: comparison with data from split-brain studies.

Two nonverbal tasks (Nebes' Figural Unification Test and Arc-Circle Matching Task) were given to 10 aphasic patients and 10 normal controls. Observations in split-brain patients have shown that the right hemisphere performs almost normally on these tasks while the left hemisphere fails completely. Left and right hand performances of aphasics and controls were compared with those of split-brain patients as reported in the literature. In the Figural Unification Test the aphasics' left hand performance was significantly poorer than that of split-brain patients. This is interpreted as an effect of left hemispheric interference with right hemispheric nonverbal performance. The lack of a similar impairment of left hand performance in the Arc-Circle Matching Task suggests that this interference is only provoked by tasks which, due to the possible verbalization of stimulus material, tend to stimulate left hemispheric activity.

Aged↗
PubMed1987

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.

Brain Diseases↗
PubMed1987

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.

Adult↗
PubMed1986

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.

Adult↗
PubMed1985

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.

Adult↗
PubMed1985

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.

Adult↗
PubMed1984

Electromyographic feedback treatment of chronic hemiparesis: an attempt to quantify treatment effects.

The efficacy of electromyographic (EMG) feedback for the treatment of chronic upper extremity hemiparesis was quantitatively assessed through a series of objective and standardized tests of motor skills given to 12 stroke patients before and after treatment. In addition to standardized tests, video recordings of patient performance during simple motor tasks were made before and after EMG feedback training to permit subjective ratings of patient performance. Only six patients were able to perform the standardized tests of motor skills in a way permitting meaningful evaluation of results, and their test scores showed no significant improvement after treatment. Ratings of the video records by 37 independent physical therapists showed that some improvement of gross motor performance could be observed at the level of subjective global evaluation.

Adult↗
PubMed1983

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.

Acoustic Stimulation↗
PubMed1982

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.

Adult↗
PubMed1978

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.

Brain Damage, Chronic↗