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PubMed1979

Schizophrenia: evidence of a subgroup with reversed cerebral asymmetry.

Normal right-handed individuals often show neuroanatomical asymmetries of the brain on computed tomography (CT), with wider right frontal and left occipital lobes. We examined the frequency of reversals of this normal asymmetry in a group of 57 right-handed, the schizophrenic patients. Compared to 80 normal right-handeders, the schizophrenics had an increased frequency of both frontal and occipital reversals. We then divided the patients on the basis of whether they had CT evidence suggestive of brain atrophy. Those without evidence of atropy had increased frontal and occipital reversals. Those with evidence of atrophy had no increase in reversals. This suggests that reversals of neuroanatomical asymmetry, and by implication abnormalities of lateralization, are relevant to a subgroup of schizophrenic patients with otherwise normal CT scans.

Adult↗

PubMed1980

Indonesian "Solo" (Ngandong) endocranial reconstructions: some preliminary observations and comparisons with Neandertal and Homo erectus groups.

Latex rubber brain endocasts of solo I, V, VI, X, and XI crania were prepared in order to determine accurate volumes by H2O-displacement and morphological description. The new volumes are not markedly different from previous estimates that had been done by mensuration formulae. The mean volume is 1,151 ml. The endocast surfaces, while devoid of gyral and sulcal relief patterns, do show a preponderance of left-occipital-right-frontal petalia patterns, suggesting right-handedness. Metrical observations support the viewpoint that the solo crania are more closely related to earlier Indonesia homo erectus than to Neandertals.

Animals↗

PubMed1981

Volumetric and asymmetry determinations on recent hominid endocasts: Spy I and II, Djebel Ihroud I, and the Sale Homo erectus specimens, with some notes on Neanderthal brain size.

Full brain endocast reconstructions of the Neanderthals, Spy I and II, Djebel Ihroud I, and the Homo erectus specimen from Sale, Morocco have yielded accurate volumes. Spy I = 1,305 ml; Spy II = 1,553 ml; Djebel ihroud I = 1,305 ml; Sale = 880 ml. While there are no remarkable gyral and sulcal patterns one can delineate, the brain endocasts do show evidence of left-occipital, right-frontal petalias, suggesting right-handedness, and possibly human cognitive specialization, involving symbol processing and visuospatial integration. Some speculations regarding Neanderthal brain size are also offered, in which it is suggested that their possibly larger brain sizes were related to greater muscularity than in modern Homo sapiens.

Animals↗

PubMed1981

Right-hand preference facilitated by rightward turning biases during infancy.

A rightward turning bias is the earliest human asymmetry and may be a precursor of handedness. Head-turning affects arm position as part of the Asymmetric Tonic Neck Reflex (ATNR). The hypothesis was tested that turning biases operate in coordination with the ATNR to promote handedness by measuring reflex behavior during turns in the preferred vs nonpreferred direction. Twenty infants were filmed during spontaneous movement and during the following factorial design: head turned left vs right; voluntarily vs passively; 30 degrees vs 70 degrees. The incidence, strength, and duration of the ATNR were least when the child turned toward his/her preferred side. When right-preference children turned rightward, the occurrence of the ATNR was no better than chance. Thus, a child can orient toward the right hand with minimal intrusion of the ATNR upon limb position, perhaps promoting right-handedness.

Elbow Joint↗

PubMed1984

Pathological left-handedness and ambiguous handedness: a new explanatory model.

A new model is presented which attempts to explain three pathological handedness phenotypes: pathological left-handedness (PLH), pathological right-handedness (PRH) and ambiguous handedness (AH). Revisions in the original model of PLH were prompted in order to account for reports of a raised incidence of both manifest left-handedness and AH in more severely retarded and/or brain-injured populations--namely, autistic. The new model generates specific predictions on the likelihood of different etiological subgroups within these disorders.

Autistic Disorder↗

PubMed1985

Infant rightward asymmetries predict right-handedness in childhood.

Eight children for whom measures of head preference and hand visualization had been determined in infancy were evaluated by parent questionnaire for hand preference at ages 3.5-6 yr. All six infants who maintained their heads to the right became right-handed as predicted, while neither infant with a non-right head orientation developed handedness in the predicted direction, though neither became right-handed. Similarly, the five infants who had visualized their right hands more frequently than the left became right-handed children as predicted; of the three infants who did not visualize the right hand more frequently, none developed handedness as predicted. None of the infant measures correlated with childhood handedness. These results suggest support for the genetically based right shift factor proposed by ANNETT (Behav. Genet. 8, 227-249, 1978).

Child↗

PubMed1986

The influence of gender, handedness and head-turn on auditory asymmetries.

Subjects performed dichotic tasks with their heads turned 90 degrees to the left, 90 degrees to the right, and straight ahead. In Experiment 1 the stimuli were digits and the subjects varied in both sex and handedness. Right-handedness males showed a significant right-ear advantage under the head-right and head-straight conditions, while left-handed males and both right- and left-handed females failed to show any consistent ear asymmetries. In Experiment 2 the stimuli were melodies and the subjects were all right-handed. Head-turn had no significant influence on the results, and only the males showed a significant left-ear advantage. Overall, the results confirm previous findings that sex and handedness may influence auditory asymmetries, but fail to reveal systematic effects of head turn.

Adolescent↗

PubMed1980

The handedness distributions of gifted and non-gifted children.

The handedness distribution of a group of 578 gifted elementary school children (I.Q. = 132) was compared to handedness distribution of 391 non-gifted children (I.Q. less than 132), with the result that the gifted group was significantly less right-handed than their non-gifted peers. These data were discussed relative to Bakan's hypothesis that left-handedness results from stressful prenatal and birth conditions. In addition attention was paid to the possibility of a non-linear relationship between intelligence and degree of right-handedness.

Child↗

PubMed1983

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.

Adolescent↗

PubMed1989

Handedness and anxiety in normal and clinical populations.

Previous research has yielded inconclusive evidence as to the relationship between handedness and anxiety. In order to further examine this relationship, two studies were carried out. In the first study, university students (N = 167) completed the Edinburgh Handedness Inventory, the Fear Questionnaire, and the Maudsley Obsessive Compulsive Inventory. No evidence was found to suggest that phobic fears are more prevalent or more severe among individuals with a tendency to left-handedness than among pure right-handers. Statistical tests reveled a marginally significant positive association between social phobia scores and right-handedness. In the second study, handedness was assessed in 77 anxiety disorder patients and compared with handedness patterns in normal controls. Again, no support was found for the claim that anxiety and left-handedness are related to each other. However, the normal pattern of women being more right-handed than men was reversed in the anxiety disorder group.

Adult↗

PubMed1975

Frequency of left-handedness among the Andhra Pradesh people.

The percentages of left-handed people among the males and females of Andhra Pradesh tribals in India were found to be 15.49 and 7.79, and in Hindus 6.9 and 4.65. The difference between the sexes among tribals is significant. The tribal people studied were Koya Doras, Sugalis (or Lambadis), and Konda Reddis. It is suggested that similar quantitative studies of left-handedness should be made in other tribal and aboriginal populations before they are culturally comditioned to right-handedness.

Ethnicity↗

PubMed1993

Are age trends in adult hand preference best explained by developmental shifts or generational differences?

Hand use in the performance of six everyday activities was analyzed as a function of age in a sample of 654 adults. An unskilled grasping tasks showed the largest shift toward consistent right-handedness as a function of age; skilled manipulation tasks, such as writing, exhibited weaker age-related trends. Analysis of individual preference patterns showed decreases in mixed right hand use (defined as a right-hander who occasionally uses the left hand) and increases in consistent right hand use in older adults. There was also a weaker age-related reduction in mixed left hand use but the numbers of consistent left-handers remained a small, constant percentage of the sample across all age groups. These results are congruent with the predictions of two developmental hypotheses offered to explain trends in adult hand preference. These are, first, a postulated age trend toward hand preference consistency and, second, a practice effect related to an environment arranged to favor right hand use.

Adolescent↗

PubMed1991

Sex, handedness, mathematical ability, and biological causation.

An important part of Benbow's (1988) assertion that sex differences in mathematical ability are primarily due to biological factors is the link between a trait that is assumed to reflect differences in brain organization (left-handedness) and mathematical giftedness. It is shown that the link between mathematical giftedness and an increased prevalence of left-handedness is not convincing. However, Benbow's (1986) data do show a convincing link between strong right-handedness and the lack of mathematical giftedness, in agreement with Annett and Manning's (1990a, 1990b) recent work.

Aptitude↗

PubMed1994

Handedness and sexual orientation.

Surveys of handedness distribution (i.e., the distribution across handedness categories in large samples, typically based upon self-reported right-, mixed- and left-handed classification) indicate approximately 90% of the population is right-handed (Springer & Deutsch, 1989). This distribution toward right-handedness has been called right shift based on a genetic model (Annett, 1985). The present study examined possible handedness distribution differences between 141 gay, lesbian, and bisexuals and 260 heterosexuals who have a homosexual/bisexual first-degree (biological) relative. Based on a five-category self-assessment handedness questionnaire that was validated using Briggs and Nebes' (1975) reformulation of Annett's inventory (1970), non-heterosexuals showed a reduction of right shift compared to heterosexuals (i.e., a population shift toward mixed- and left-handedness), confirming the results of Lindesay (1987) and Becker et al., (1989). Sexual orientation also weakly predicted handedness. The findings indirectly support the hypothesis of Geschwind and Galaburda (1985a, 1985b) that sexual orientation and handedness may be linked, both possibly influenced prenatally by testosterone. The discussion emphasizes (a) the meaninglessness in distinguishing genetic from hormonal influences and (b) non-heterosexually biased assumptions about human sexuality.

Adult↗

PubMed1985

Hand preference in schizophrenics and handedness conversion in their childhood.

A handedness questionnaire which was given to 1774 schizophrenic inpatients was identical to that employed in our previous study on healthy students. Information was obtained on forced conversion of hand usage in childhood and the occurrence of left-handedness in their families. Family history of schizophrenia was also investigated. There were no significant differences in the prevalence of left-handedness or non-right-handedness (i.e., left-handedness and ambidexterity combined) between schizophrenic patients and normal subjects. However, the rate of converted right-handedness in schizophrenics was higher than that in normal people. The incidence of original non-right-handedness (i.e., present non-right-handedness and converted right-handedness combined) in schizophrenics was greater than that in normal controls.

Adolescent↗

PubMedDate not supplied

Right and left hand skill in relation to cerebral lateralization in right-handed male and female subjects: the prominent role of the right brain in right-handedness.

The associations between right and left hand skills to cerebral motor lateralization were studied in right-handed subjects with (FS+) and without (FS-) familial sinistrality. Hand preference was assessed by Oldfield questionnaire and hand skill by the peg moving task. The mean peg moving times (PMTs) and their standard deviations (SDs) were calculated for each hand. There was a significant positive linear correlation between the mean right and left hand PMTs. In males, the mean difference between the left and right PMTs (L-R) showed a significant negative linear correlation with the mean right hand PMTs. There was no significant correlation between these parameters in females. The mean L-R PMTs were found to be positively linearly correlated with the mean left hand PMT in FS- males, FS- and FS+ females (no correlation in FS+ males). The results indicated the contribution of the mean left hand PMTs to L-R hand skill is much higher than that of the mean right hand PMTs. In males, there was no significant correlation between SDs of the mean right and left hand PMTs. In females, SD of the mean right hand PMT was found to be positively linearly related to SD of the left hand PMT. In males, L-R SDs were found to be negatively linearly related to SDs of the mean right hand PMTs and positively linearly related to the SDs of the mean left hand PMTs. In females, only the mean left hand PMT positively linearly correlated with L-R SDs. Here again, the left hand prominently influenced the L-R SDs. In males, SD for the mean right hand PMT showed no relation to right hand PMT. There was, however, a negative linear correlation between SD of the mean right hand PMT and the left hand PMT (no correlations in female). It was concluded that the left hand (right brain) would be of higher significance than the right hand (left brain) in determining the degree of the right-bias in hand skill and its stability in right-handers.

Adult↗

PubMed1994

Handedness and allergic response.

Previous reports have linked nonright-handedness with allergies including hay fever, asthma, eczema and urticaria. The present study examined reactions to 20 common allergens (e.g., food, animal fur, dust, drugs, etc.) in a sample of 430 subjects. Individuals who were left-handed or not consistently right-handed showed an elevated frequency of allergic reactions. The criteria used to determine handedness and the existence of allergies are both important factors. The stringent criterion of consistent right-handedness versus nonright-handedness was a more sensitive measure in detecting allergic individuals than was the simple dichotomy of left- versus right-handed. The association with handedness was stronger for individuals with more than one allergy.

Adolescent↗

PubMed1978

[Neuroradiologic and clinical correlations in asymmetric lateral ventricles and posterior cornua in pneumo-encephalograms (author's transl)].

Retrospective study of 452 out of 4155 pneumoencephalograms continuously investigated by two independent observers over 20 years. Follow-up and statistics of frequency and sex-differences of asymmetries of lateral ventricles and posterior cornua. Criteria of selection: history and clinical findings in favor of a general cerebral cause and against circumscribed changes due to local damage. Technique standardized and equal bilateral filling in pneumoencaphalography. Results of the numerous findings: 1. Posterior cornua were symmetrical in 370 patients 81.9% (256 male, 114 female, 18.1%). Definite asymmetry of posterior horns in 72 males and 10 males. 2. These asymmetries showed variations from unilateral to bilateral, but clearly different sizes of posterior horns. 3. Unilateral posterior horn "anlagen" seen in 64 (14.1%) of all patients. Males predominated 8:1, left more common than right 3.5:1. 4. Bilateral "anlagen", with one posterior horn predominating, in 18 patients (3.9%). Once more males more common 8:1. Larger "anlagen" on left: 8:1. 5. Accompanying further asymmetries of lateral ventricles with equal bilateral posterior horns were of similar size in 73.7%. In 21.1% the lateral ventricle was larger on the right, in 5.1% on the left. The left side was more common 4.15:1. 6. Large ventricles were of equal size in 45.1 of patients with asymmetry of the posterior horns, 45.1% on left, 9.7% on right the ventricle was larger. Once more the left side predominated 4.6:1. 7. Trying to correlate clinical-neurologic, neurophthalmic, neurophysiologic and tachistocopic findings with pneumoencephalograms with or without asymmetry showed no regular relation with handedness, ocular dominance, limitations of visual fields or--neglect or shapes of ventricles. In all subgroups frequency and sex-distribution corresponded to the norm. 8. Numerical frequency of coupling of right-handedness and right predominant eye with left increased size of ventricle was within the statistically expected and was, therefore, not interpreted as a sign of functional dominance of the left cerebral hemisphere, as done by others. 9. When eliciting from the occiput visually evoked potentials 8 patients showed important findings, in spite of their small number. In 3 patients with symmetrical "anlagen" of the posterior horns, latency and amplitude of potentials were the same; in 5 patients, with asymmetry of posterior horns the side of the larger horn showed significant reduction of amplitude without exception. The investigations show, quantitative statistical findings of frequency and sex-distribution and their negative correlation with examined clinical parameters apart, the anatomic-morphologic variation of asymmetry of posterior horns corresponds to a correlate which can also be shown with a neurophysiologic technique.

Adult↗