Masaomi Endo

Handedness and Familial Sinistrality in a Japanese Student Population

A handedness questionnaire consisting of thirteen items was administered to 4282 Japanese senior high school students. Information on the occurrence of left-handedness in their family as well as on forced conversion of hand usage in their childhood was obtained. Results indicated that incidence of non-right-handedness was 7.2%, with that of males being greater than that of females. The proportion of converted right-handers was greater in females than in males. When the frequency of converted right-handers was added to that of present non-right-handers, the average for non-right-handedness increased to 11%. Non-right-handers, particularly females, had familial sinistrality more frequently than right-handers. Item analysis revealed that the incidence of individuals who always use left hand for writing and eating was only 0.7% and 1.7%, respectively. This suggests that social pressure for right-hand writing and eating remains high in Japan.

Functional asymmetry of visual fields for Japanese words in kana (syllable-based) writing and random shape-recognition in Japanese subjects

Abstract Random shapes or Japanese two-syallable nonsense words (in kana -writing) were presented tachistoscopically and successively as stimulus materials to 18 normal, right-handed Japanese female students, would could view them on the right or the left sode of a central fixation point. When the stimulus coincided with a stimulus previously taught as a positive one, the subjects were required to press a button as soon as possible, and the reaction time was measured. Analyses of variances for reaction times of correct responses indicate that the difference between the visual fields is significant for each type of recognition, regardless of the responding hand, and that there is a left visual field (or right cerebral hemispheric) superiority for shape recognition and a right visual field (or left hemispheric) superiority for nonsense word recognition. These results also assure us that Japanese subjects have the same interhemispheric functional asymmetry for shape and word recognition, as subjects in Europe and America do.

Tachistoscopic recognition of Kana and Hangul words, handedness and shift of laterality difference

Nonsense Kana words as verbal stimuli and Hangul words (Korean orthographic characters) as non-verbal were presented tachistoscopically in the left or right visual field to normal right-handed, non-familial left-handed Japanese subjects, who have not seen Hangul characters. Right-handers showed a significant right (or left) field superiority for the recognition of verbal (or non-verbal) stimuli. This pattern of differences found in right-handers is, though to a slightly lesser degree, also present in non-familial left-handers, while it is absent in familial left-handers. Initial left field superiority for Hangul word recognition shifted to no laterality difference in left-handers as well as in right-handers during the learning period for Hangul words.

Comparison of Patterns of Handedness Between Twins and Singletons in Japan

The handedness questionnaire of thirteen items which was identical to that employed in our previous study on singletons was administered to 62 monozygotic (MZ) and 48 dizygotic (DZ) twin pairs in Japan. Information on forced conversion of hand usage in childhood was also obtained. Results indicated that the incidence of left-handedness was 3.6% and that of non-right-handedness (which includes mixed- and left-handedness) was 5.9%. There was no significant difference in the incidence of left-handedness or of non-right-handedness between MZ and DZ twin groups. The proportion of converted right-handedness in MZ twins was slightly higher than in DZ twins. MZ pairs were somewhat more concordant for handedness than DZ pairs. Item analysis indicated that the incidence of individuals who use the left hand for writing and eating was only 0.9% and 1.8%, respectively. A comparison of the results of the present survey on twins with those of our previous one on singletons revealed that the incidence of left-handedness or non-right-handedness in twins is the same as that in singletons. Twins (especially MZ twins) have experienced a forced conversion to right-hand usage more frequently than singletons.

CONVERGENCE OF THALAMIC AND SENSORY AFFERENT IMPULSES TO SINGLE NEURONS IN THE CORTICAL ASSOCIATION AREA OF CATS

An observation was made to ascertain that the thalamic and sensory impulses converge to the neurons of the gyrus suprasylvius medius of the cats either unanesthetized or under chloralose anesthesia (over 30 mg/kg). The starting portions of the impulses whose convergence could be ascertained are as follows:

The influence of Hangul learning upon laterality differences in Hangul word recognition by native Japanese subjects

Abstract Single-character Hangul words were presented tachistoscopically in the left or right visual field to 34 normal, right-handed Japanese subjects who did not know Hangul. The reaction time was measured. A significant left-field superiority for Hangul recognition was shown. When 18 out of 34 subjects learned Hangul stimuli, they showed no lateral asymmetry for Hangul recognition. However, the other 16 subjects, without Hangul learning, again exhibited a significant left-field superiority. The results show that the initial left-field superiority shifted to no laterality difference for Hangul recognition by poor Hangul learners.

Sleep Spindles in Twins

Sleep spindle characteristics and spindle power periodicity were studied in 4 identical and 3 fraternal twin pairs (mean age, 16 years). There were no significant genetic effects such as concordance between the identical twins and discordance between the fraternal twins for mean duration, mean amplitude and mean frequency of spindles. Spindle periodicity, which is correspondent to the sleep cycle, was visually more similar between the identical twins than between the fraternal twins. These observations suggest that the sleep cycle which is expressed by periodic appearance of spindle powers is genetically determined. On the other hand, some spindle characteristics and some physical measures had significant relationships. These relationships may suggest that some spindle characteristics are influenced by the individual development rather than by a genetic trait.

Neuronal responses in the cerebral cortex to electrical stimulation of the non-specific thalamic nuclei in cats

Abstract Cortical neuronal responses to stimulation of the intralaminar nuclei of the thalamus were compared in the motor, somatosensory and association areas of the cerebral cortex in curarized or encephale isole cats, and correlation between the neuronal responses to specific and non-specific thalamic stimulations and effects of the latter on the neuronal response to specific thalamic stimulation were investigated in the three cortical areas. The results were as follows. 1. 1. In the association area 77% of the neurons responded with “synchronization” to low frequency stimulation of the intralaminar nuclei. In the motor and somatosensory areas this response occurred in 53% and 9% respectively. These percentages are in direct ratio with the facility to induce recruiting responses in the same areas. 2. 2. Only a small number of neurons (but relatively larger in the motor than in other areas) showed decrease in rate of discharge with single shock or repetitive stimulation of the intralaminar nuclei. 3. 3. The percentage of neurons which exhibited synchronization with low frequency stimulation of both specific and non-specific thalamic stimulation (“apparent convergence”) was 75% in the association, 41% in the motor area and 8% in the somatosensory area. These neurons, on the basis of their response pattern to specific thalamic stimulation were classified as either Type I-b or I-c. The type I-c neurons did not show direct discharge with single shock to the specific thalamic system, but the Type I-b neurons could show direct discharges in response to both single shock of the specific thalamic system and low frequency stimulation of the non-specific thalamic nuclei. 4. 4. In all the cortical areas investigated, the neuronal discharges in response to specific thalamic stimulation were facilitated by antecedent non-specific thalamic stimulation and the inter-stimuli interval for maximal facilitatory effect appeared to be related to the latency of the neuronal discharges in response to specific thalamic stimulation.

Electroencephalographic findings in neuroacanthocytosis

This study reports the electroencephalographic findings in two siblings with neuroacanthocytosis. Slowing of the background activity with diffuse slow waves was the main finding in the daytime EEG. All-night polysomnographic recordings were characterized by high voltage slow activity during drowsy state and REM sleep. One patient with an average of 40 episodes of apnea per night of sleep was treated with imipramine and showed respiratory improvement.

Serial Polysomnograms in Creutzfeldt‐Jakob Disease

Abstract: This is a report of the case of a patient with Creutzfeldt‐Jakob disease, whose electroencephalograms and polysomnograms were repeatedly recorded throughout the course of the illness with details of the alterations of periodic synchronous discharges. In the advanced stage of the disease, the appearance of peculiar paroxysms was noted, predominantly in the early morning. Furthermore, apnea of the central type was observed during the same time period. Discussions were held on the mechanisms inducing the EEG paroxysms and apneas.