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Biomedical subjects

T Hatta

Publications and source records attributed to T Hatta.

At least 145 records · Page 8Linked to original sources
PubMed1984

Differences in the morphology of isometric particles of some plant viruses stained with uranyl acetate as an aid to their identification.

Purified preparations of viruses with small polyhedral particles representing ten distinct taxonomic groups were examined by electron microscopy after negative staining with uranyl acetate. Comparisons of the relative size, shape and surface appearance of the particles established that some of them could be distinguished at the group level. However, the particles of viruses belonging to the bromovirus group could not be distinguished from those of the cucumovirus group, the nepovirus group from those of the comovirus group, and the tombusvirus group from those of the dianthovirus group. Furthermore, the particles of viruses of the sobemovirus, lutoevirus and tobacco necrosis virus groups were indistinguishable. The usefulness of the observed differences in the particle morphologies to virus identification is discussed.

Microscopy, Electron↗
PubMed1984

Lateral eye movement and hemisphere asymmetry: effects of question type, task type, emotion type, and individual differences.

The validity of lateral eye movement (LEM) as an index of hemispheric activation was examined with a series of experiments. LEMs were measured to verbal and spatial questions (Experiment 1), word detection and emotion detection tasks (Experiment 2), and to negative and positive emotions (Experiment 3). The results of these three experiments showed that LEM is not a sensitive index of hemispheric activation. Experiment 4 showed that individual differences in LEM patterns is relatively stable and may reflect some personality traits.

Adult↗
PubMed1984

Dichotic listening by chronic schizophrenic patients.

The hypothesis that schizophrenics show hemispheric dysfunction (e.g., overactivation ) was examined using the dichotic listening test (words). Thirty-three chronic schizophrenic patients and 33 normal controls were tested. Their data were analysed for over-all correct identification of the stimuli presented to the left and the right ears, the magnitude of differences between the ears in recall, and the number of shifts in report from one ear to the other. The overall level of performance was lower for schizophrenics than for the normal controls; between the ears difference were not significant although schizophrenics showed large individual differences. The number of shifts was greater for normals than for the schizophrenics; and there was no sex difference on any index within the two of subjects groups. The results were discussed in relation to the hypothesized hemispheric dysfunction in schizophrenics and other aspects of cognitive activity which may underlie the performance of the task.

Auditory Perception↗
PubMed1984

Cerebral functional asymmetry and MBD children: a synergistic deficit of hemispheres?

The functional cerebral organization of minimal brain-damaged (MBD) children was studied by testing tactile-visual matching of concrete objects. The results revealed that left hand performance was significantly better than the right in the MBD children while normal controls showed no hand difference, and overall performance level was poor for MBD children. These findings are consistent with the view that tactile matching of concrete objects requires hemispheric synergy and that MBD children lack this synergy.

Adolescent↗
PubMed1984

Functional hemispheric differences in schizophrenia: interhemispheric transfer deficit or selective hemisphere dysfunction?

Two hypotheses concerning functional hemispheric organization in schizophrenic patients were examined in two experiments. In the first experiment 35 chronic schizophrenics and 35 normal controls performed tactile-visual matchings with each hand. The results showed that the performance level of the schizophrenics was inferior to that of the normal controls, but did not show any hand difference. In the second experiment chronic schizophrenics and normal controls made intermanual matchings and intramanual matchings with successively presented nonmeaningful shapes. The results revealed that the intermanual matchings of the schizophrenics were significantly inferior to those of the controls but there was no subject group difference in the intramanual matchings. These results did not lend support to the hypothesis that schizophrenics have selective left hemisphere impairment, but suggest that there may be an interhemisphere interaction deficit in schizophrenic patients.

Adolescent↗
PubMed1984

[Functional hemisphere differences in auditory and tactile recognition in aged people].

The effects of aging on hemispheric specialization in verbal and visuo-spatial functions were examined by dichotic listening and tactile recognition tests. In the first experiment, thirty aged (65-91 year) intact subjects and university students were tested by a dichotic listening tape with pairs of two-syllable meaningful words. The results revealed an overall decline of scores in the aged subjects but there was no interaction between subject and the degree of right ear advantage. In the second experiment, subjects were asked to judged whether successively presented nonsense tactile stimuli to each hand were identical or not. Reaction times and accuracy rates of each hand of the aged subjects were inferior to those of the control subjects. However, no interaction was found between hand and subject group. Both experiments show that there is no evidence to suggest any selective deterioration or specialization of hemispheric function in the aged people, though overall performance level declines with age, which may be caused by short-term memory deficit.

Adult↗
PubMed1983

Visual field differences in semantic comparative judgments with digits and Kanji stimulus materials.

Hemisphere specialization for two types of semantic comparative judgments were examined. In the first experiment a pair of Arabic numerals of different physical size were displayed and subjects were asked to judge if the physical size of the stimulus and the numerical magnitude were congruent or not by pressing the appropriate button. Reaction times were faster in the right visual field than in the left visual field. In the second experiment a pair of different physical sized Kanji representing concrete objects were displayed and subjects were required to judge if the physical size of the Kanji was congruent or not with the relative real life object size by pressing the appropriate button. Reaction times were faster in the left visual field. In the third experiment a pair of different physical sized Kanji representing numerical magnitude were displayed and subjects judged if the physical size of the Kanji and the numerical magnitude were congruent or not. Results showed a right visual field advantage and eliminated the possibility that Kanji complexity was the cause of the left visual field advantage in the second experiment. These results were interpreted as providing support for the proposal that there are two types of semantic comparative judgments, one relying on the verbal code and the other relying on the use of imagery, and suggesting that the former calls for stronger engagement of the left hemisphere while the latter calls for a stronger contribution from the right hemisphere.

Adult↗
PubMed1983

Event-related potentials and reaction times as measures of hemispheric differences for physical and semantic Kanji matching.

Hemispheric differences associated with Physical Identity Matching and Semantic Classification of Japanese characters (Kanji) were examined using visual event-related potentials and behavioural measures. Event-related potentials to the Kanji during matching tasks revealed hemispheric differences in the later components. Right hemisphere responses were larger than those or the left. The interaction of Types of Matches by Hemispheres was not significant. This interaction however was significant with the behavioural measure. On Semantic Classification Matching reaction times for right-visual-field Kanji were faster than those of the left field while no visual field difference was found for Physical Identity Matching. The sensitivity of both measures as indicators of laterality is discussed from the point of view of levels of processing.

Adult↗
PubMed1983

Does single Kanji process dominantly in the right hemisphere? Some implication from Stroop-test results.

Naming times to single character Kanji, which consisted of small alphabetic letters, Kanji (Stroop stimuli), and solid lines, presented in the left or the right visual field were measured. When subjects tried to respond to Alphabet Stroop stimuli, they showed a greater interference effect in the case of right visual field presentation. Kanji Stroop stimuli yielded no visual field difference in the size of interference effect. These findings suggest that Kanji has a different property from phonetic symbols and a specialization of the right hemisphere for single character Kanji processing.

Adult↗
PubMed1983

Language processing in partial English-Japanese bilinguals: evidence from Stroop-test results.

Possible hemispheric functional differences between adolescent partial English-Japanese bilinguals and Japanese monolinguals were examined with a reversed auditory Stroop test. Subjects were requested to press their left/right hand button when they heard the target Japanese word "Otoko (male)/Onna (female)" as fast as possible. In one condition, the word and the speaker's sex weed congruent and in the other condition they were incongruent. The results of the reaction times showed that Stroop effects appeared with both responding hands in the bilingual group. On the other hand, the results of the monolinguals revealed that the Stroop effect was shown only with the left hand and not with the right hand. These results suggest that in nonproficient bilinguals, the right hemisphere may be involved in processing word meaning.

Adolescent↗
PubMed1983

[A new test for hemisphericity: the examination of its validity and reliability].

A new cognitive test for hemispherecity, based on the knowledge of hemispheric functional differences, was developed. In the first experiment, fifty subjects were examined their preferences for either visual-spatial or visual-verbal processing to the stimuli to which both types of processing were available. In the second experiment, ERP (Event Related Potentials) were measured in the two conditions: One, subjects processed the stimuli used in the first experiment as the visual-nonverbal stimuli, the other, subject processed the same stimuli as the visual-verbal stimuli. ERP from the left and the right hemispheres differed between both conditions in the later components. In the third experiment, both groups of subjects who preferred visual-verbal processing and visual-nonverbal processing were asked to report the Hiragana words presented tachistoscopically to the left or the right visual field. The former group of subjects showed a significant right visual field advantage while the latter group of subjects showed no visual field difference. These results confirm that the newly developed test for hemispherecity has appropriate validity and reliability.

Adult↗
PubMed1982

Developmental changes in letter recognition as affected by parafoveal noise.

The effect of parafoveal noise information on a Hirakana target-recognition task was investigated with 10 good and 10 poor readers in first and second grades (ns = 20 per grade). A differential effect of parafoveal noise produced a longer or shorter variation in RT depending on the kind of surrounding material. This suggests that the filtering mechanism whereby unnecessary information is avoided becomes more efficient from the first to the second grade of school attendance.

Attention↗
PubMed1982

Differential effects of concurrent letters on visual field differences in letter recognition.

To examine whether concurrently presenting surrounding scripts affect single Alphabet recognition, subjects compared letters which appeared in the left or the right visual field to a previously presented sample letter. Four different comparison stimuli were prepared, target letter embedded in same-type print letters, in different-type letters, in different kinds of characters, and in blank space (control). The results indicated that both RTs for letter matches and visual field differences were different depending upon the kind of letters that surrounded the target Alphabet. This finding strongly suggests that letter recognition is affected by the presence of neighbouring letters, and further that the nature of the surroundings can differentially affect cerebral hemispheric functioning.

Attention↗
PubMed1982

Handedness and imbalance lateralization on the Tapping Test in MBD children.

Twenty MBD children and thirty-eight normal control children were tested for handedness and for lateralization on a Finger Tapping Test. The frequency of nonright handedness in normal children was 16%, whereas it was 60% in MBD children. The significance of this difference was discussed. The "imbalance" hypothesis in regard to the Tapping Test was examined. The hypothesis that "extreme" laterality is more in MBD children than controls was not supported in this study.

Adolescent↗
PubMed1982

Sex differences in hemispheric function: implications from a hemispheric time sharing task.

A microcomputer controlled test of hemispheric time sharing was conducted on normal male and female students. Subjects engaged in a unimanual task involving sequential finger movement alone and in two conditions with concurrent cognitive activity. The verbal task interfered more with right than left hand activity in both male and female subjects. The spatial task interfered more with left than right hand activity in male subjects while female subjects did not show any hand differences. Possible sex differences in brain function were discussed.

Adult↗
PubMed1982

Hemispheric asymmetry and sex differences in a comparative judgement task.

Visual field differences and sex differences in a complex semantic processing task were examined. Two different print size Kana words which represented concrete objects were paired and displayed tachistoscopically to the left or the right visual field. Subjects decided if the relationship of the print size and real life size of the word pairs was appropriate or not by pressing a key. Results revealed that female subjects showed faster reaction times to the right visual field stimulation while males showed a tendency toward a left visual field superiority. Possible hemisphere difference in mechanisms between the sexes were discussed.

Brain Mapping↗