Left-sided Laterality Research Articles

The risk of ultraviolet exposure for melanoma in Fitzpatrick skin types I-IV: A 20-year systematic review with meta-analysis for sunburns.

Within the last two decades, no studies have comprehensively reviewed the risk of varying types of ultraviolet (UV) exposure on melanoma in fairer skinned individuals. Our research objective was to determine whether or not there was a change in the risk of UV exposure with development of melanoma in Fitzpatrick skin types I-IV based on more recent data over the past 20 years. We performed a systematic review from January 2002 to December 2021 analysing UV exposure and melanoma risk in Fitzpatrick type I-IV individuals. Out of 19,852 studies, 26 met inclusion criteria. Data spanned subjects from national and multinational cohorts (USA, Europe, Australia, Asia and South America). Twenty studies (77%, 20/26) identified a significant association between UV exposure and melanoma incidence. Sunburn was the most commonly assessed risk factor. Sunburn studies encompassed 3417 melanoma and found positive significant odds ratios (OR [95% CI]) in 11 out of 13 studies, ranging from 1.23 [1.01-1.49] to 8.48 [4.35-16.54]. Pooled analysis of the risk of melanoma with sunburn history found an unadjusted odds ratio of 1.66 [1.40-1.97] and adjusted odds ratio of 1.23 [1.04-1.46]. Cumulative sun exposure, measured as number of hours of sun exposure or calculated UV flux, was the second most common risk factor, encompassing 913 melanomas with positive significant ORs ranging from 1.1 [1.0-1.2] to 5.2 [2.1-12.5]. For other forms of UV exposure, a majority of studies showed an association with UV index (6/9), outdoor leisure activity (3/3) and left-sided laterality (1/1). Overall, UV exposure should continue to be considered a modifiable risk factor for melanoma in individuals of fairer skin.

Bell's Palsy, an Adverse Event Following COVID Vaccines.

Bell's palsy is one of the most concerning complications of the COVID vaccine that has impacted vaccine acceptance among the general population. These vaccines were introduced to provide immunity against the SARS-CoV-2 coronavirus and have been found to be quite effective. Little did we know that Bell's palsy could be one of its serious complications. We used various search engines to gather data in the form of a case series and case reports related to patients who were affected by the vaccine and had developed Bell's palsy. A total of eleven case reports and 4 case series were included in the analysis. The vaccines mentioned in the case reports were Pfizer, Moderna, Sinovac, AstraZeneca, and Janssen, while the case series included Pfizer and Sinovac. The majority of patients were female and aged between 31-40 years. Right-sided laterality was observed in 45.45% of patients, left-sided laterality in 45.45% of patients, and bilateral laterality in 9.1% of patients. Three patients had a history of Bell's palsy or stroke. After treatment, three patients showed partial improvement, six patients fully recovered, and the status of two patients was unknown. Bell's palsy is a rare complication that can occur after receiving the COVID-19 vaccine. This review aims to increase awareness about this rare adverse event of the vaccine so that it can be properly addressed and managed. Additionally, it will serve as a foundation for future research on the administration of the COVID-19 vaccine.

Craniofacial Growth and Asymmetry in Newborns: A Longitudinal 3D Assessment.

Objective: To evaluate the development of the craniofacial region in healthy infants and analyze the asymmetry pattern in the first year of life. Methods: The participants were grouped by sex and age (1, 2, 4, 6, 9, and 12 months) to receive three-dimensional (3D) photographs. Stereoscopic craniofacial photos were captured and transformed into a series of craniofacial meshes in each group. The growth patterns of the anthropometric indices and the degree of craniofacial asymmetry were measured, and average craniofacial meshes and color-asymmetry maps with craniofacial asymmetry scores were calculated. Results: A total of 373 photographs from 66 infants were obtained. In both genders, the highest and lowest growth rates for all anthropometric indices were noted between 1 and 2 months and between 9 and 12 months, respectively. Overall, male infants had higher anthropometric indices, head volume, and head circumference than female infants. The craniofacial asymmetry score was presented with a descending pattern from 1 to 12 months of age in both sex groups. Both sex groups showed decreased left-sided laterality in the temporal-parietal-occipital region between 1 and 4 months of age and increased right frontal-temporal prominence between 6 and 12 months of age. Conclusions: A longitudinal evaluation of the craniofacial growth of healthy infants during their first year of life was presented.

32131 Updating the relative risk of ultraviolet exposure and melanoma in fair skin types: A systematic review

In 2005, a meta-analysis found that varying types of UV exposure contributed to an increased relative risk of melanoma. Recently, a 2021 review failed to establish a similar link in individuals with skin of color. Within the last 2 decades, no studies have comprehensively reviewed the risk of varying types of UV exposure on melanoma in fair skin. Thus, we performed a systematic review from 2002-2021 analyzing UV exposure and melanoma risk in Fitzpatrick type I-IV individuals. Out of 12,263 studies, 26 met inclusion criteria. A majority showed an association with UV index (6/9), left-sided laterality (1/1), sunburn history (11/13), and outdoor leisure activity (3/3). UV index studies were all ecological and presented primarily positive correlations. For sunburn history, studies encompassed 2309 melanomas, and significant odds ratios (OR) ranged from 1.69 (1.00-2.98) to 8.48 (4.35-16.54) with higher odds ratios for increasing numbers of sunburns. For outdoor leisure correlating with prior definitions of intermittent sun exposure, studies encompassed 514 melanomas, and ORs ranged from 2.70 (1.04-6.80) to 4.18 (1.83-9.93). A positive association was found in 2 (n = 2/6) studies for cumulative or annual sun exposure, 2 (n = 2/5) studies with occupational sun exposure, 2 (n = 2/4) studies with sun vacations, and 0 (n = 0/2) studies with latitude. This study highlights the significant relationships between specific types of UV exposure and melanoma at higher rates than previously summarized due to an emphasis on fair skin types. Critically, there remains high heterogeneity in how UV exposure is captured that may contribute to mixed results.

Laterality and site-specific distribution patterns of Lentigo Maligna and Lentigo Maligna Melanoma

Background: Melanoma has been described to have preferential left-sided laterality on the human body. The distribution and invasion patterns of lentigo maligna (LM) and lentigo maligna melanoma (LMM) have not been well described.
 Methods: This was a cross-sectional, retrospective study at a single, academic center. LM and LMM cases from 2008-2018 in the dermatopathology registry were analyzed.
 Results: A total of 392 cases were included (241 LM and 151 LMM). There was no laterality preference overall. The only exception were neoplasms located on the head/neck, which showed a left-sided laterality. LM and LMM had the highest incidence on the head/neck, followed by upper extremities, trunk, then lower extremities. Men had a higher incidence on the head/neck and trunk, while women had a higher incidence on the extremities. Interestingly, the upper extremities and the right side of the female body had a higher propensity for invasive lesions.
 Conclusion: While melanomas demonstrate preferential left-sided laterality, LM and LMM only share this pattern in respect to the head/neck region. Our results complement previous study findings which characterize LM and LMM as a head/neck and upper extremity pathology. Finally, our study suggests that certain body sites and laterality have an increased propensity for invasion.

18227 Side effect: Characterizing laterality and site-specific patterns in lentigo maligna and lentigo maigna melanoma on the human body

Melanoma is known to have a left-sided laterality, yet few studies have examined the anatomic variations in the subtypes lentigo maligna (LM) and lentigo maligna melanoma (LMM). Here we aimed to examine laterality and anatomic distribution of LM and LMM at a single university center. A total of 392 biopsy cases (241 LM and 151 LMM) from 2008 to 2018 were included in this study. Chi-square tests were used to evaluate LM/LMM based on gender, body site, laterality, and metastasis. Analysis of variance models were used to compare Breslow depth. There was no overall statistically significant laterality (left 54.5% vs right 45.5%, P = .0890), however, there was a significant increase in left-sided LM/LMM on the head/neck (left 59.1% vs right 40.9%, P = .0178). LM/LMM showed the following frequencies per body site: head/neck 49.7%, upper limbs 25.3%, trunk 16.8%, and lower limbs 8.3%. Men demonstrated a higher incidence of LM/LMM on the head/neck and trunk (head/neck men 58.2% vs women 35.0%, trunk 18.9% men vs 13.3% women, P < .0001), while women showed a higher incidence on extremities (upper limbs men 20.5% vs women 33.6%, lower limbs men 2.4% vs women 18.2%, P < .0001). There was a significant increase in metastasis on the upper limbs (LMM:LM ratio 1.11 upper limbs; P = .0018) and on the right side of the female body (LMM:LM ratio 1.36 right; P = .0257). Overall, LM/LMM does not share left-sided laterality patterns with melanoma, except when on the head/neck. Like melanoma, LM/LMM is commonly found on the head/neck and upper extremities. These findings may aid in diagnosis of LM/LMM.

Prevalence and Utilization of Obturator Artery Anatomic Variant in Autologous Breast Reconstruction.

The objective of this study is to quantify the prevalence and describe the utilization of an anatomic vascular variant in which the obturator artery (OA) arises from the trunk of the deep inferior epigastric artery (DIEA) in stacked/dual-pedicled autologous breast reconstruction. When this variant is identified preoperatively on computed tomography angiography (CTA), it may be utilized in a "flow-through" fashion to direct antegrade internal mammary artery (IMA) flow into a second free flap to facilitate anastomotic arrangement and optimize perfusion. Preoperatively obtained abdomen/pelvis CTA imaging of 121 autologous breast reconstruction patients were retrospectively reviewed for the unilateral or bilateral presence of the OA branch arising from the DIEA (OA variant). The results were analyzed using descriptive statistics. Our analysis revealed the presence of the OA variant in 60 of the 121 (49.6%) breast reconstruction candidates, either unilaterally or bilaterally. Out of these patients, the variant was present unilaterally in 33 (55%) and bilaterally in 27 (45%) patients. Of the unilateral variants, 12 (36.4%) patients demonstrated right-sided laterality, while 21 (63.6%) patients demonstrated left-sided laterality. Clinically, this anatomic variant has been utilized in several cases of autologous breast reconstruction with flap survival in all cases. Utilization of this anatomic variant in stacked or dual-pedicled autologous breast reconstruction results in antegrade IMA perfusion of both primary and secondary flaps, as well as improved size match compared with other anastomotic options. Knowledge of the vascular anatomy and variations in the inferior epigastric system is crucial to both preventing complications and optimizing flap planning and outcome.

Expression of Lefty predicts Merkel cell carcinoma-specific death.

Lefty and Nodal are transforming growth factor β-related proteins, which, beside their role in determination of laterality during embryogenesis, have also been linked with cancer progression. Prompted by the observed significant left-sided laterality of Merkel cell carcinoma (MCC), we addressed whether Lefty and Nodal are expressed in MCC and correlated expression patterns with clinical parameters such as MCC laterality and patient outcome. Expression of Lefty and Nodal in primary MCC was assessed in 29 patients by immunohistochemistry. The histology (H-)score was calculated and correlated with clinical parameters. The median (range) H-score of Lefty and Nodal was 17.6 (0-291) and 74.9 (0.7-272), respectively. There was a significant correlation between Lefty expression and Nodal expression (correlation coefficient of 0.60, P=0.0006). There was no significant correlation between Lefty expression and Nodal expression with either tumour laterality, gender, age, Merkel cell polyomavirus status, disease stage, anatomical localization of primary tumours or disease relapse. On univariate analysis, low Lefty expression and Nodal expression were significantly associated with MCC-specific death (P=0.010 and P=0.019, respectively). On univariate analysis, low Lefty expression was the only significant independent predictor for MCC-specific death (P=0.025) as indicated by an odds ratio of 14 (95% CI: 1.43-137.33). Lefty and Nodal are frequently expressed in MCC, but not correlated with tumour laterality. Importantly, our data suggest that a low level of Lefty expression in primary MCC is a strong predictor of MCC-specific death.

Sheep Quickstep while the Floor Rock and Rolls: Visuomotor Lateralization during Simulated Sea Travel.

Simple SummaryDuring livestock transport the floor of the vehicle moves in a way that can disturb their balance. This can stress the animals, producing signals that are processed by the right half of their brain. This half of the brain controls movement of the sheep on the opposite, left side of their body. Hence we investigated whether limb movement was more pronounced on this side, providing evidence of stress responses. We found that sheep limb movements were increased in their left hindlimb and right forelimb during balance correction when the floor movements were most unpredictable. This may be explained by sheep using their back right leg as a pivot. We further tested which side sheep lie down on from internet pictures and found a preference for left side lying. We conclude that sheep balance correction shows evidence of a preferred use of limbs, which suggests that sheep are stressed by floor motion.Unpredictable floor motions during transport disturbs animals’ balance, requiring stepping to move the centre of gravity in the direction of body movement. When repeated regularly, this may be stressful, requiring involvement of the right brain hemisphere, hence we investigated the existence of behavioral laterality in sheep during prolonged floor motions. Six sheep were restrained in pairs on a programmable rocking platform, in which they were unable to turn around. They were exposed to three continuous rocking motion treatments (roll, pitch or both) in a regular or irregular pattern for 1 h periods in a changeover design. Right forelimb and left hindlimb diagonal stepping was more frequent in response to the motion treatment of irregular roll and pitch, which previous research has suggested to be the most stressful from heart rate measurements. An overall strategy to maintain balance appeared to be the use of the right hindlimb as a stabilizer, which was repositioned least often of all limbs until towards the end of the hour of experimental treatment. Of each tested pair, sheep restrained on the left side of the rocking floor stepped significantly often than its partner restrained on the right side, and we postulate the existence of visuomotor lateralization as left restrained sheep were unable to view their partner within the field of view of their left eye. We also investigated which side sheep lie down on, which if left lateralized could explain our observed bipedal diagonal control of sheep balance under stress. From the observation of 412 web-based images of sheep, there was an overall left-sided laterality to their lying, as has been observed in cattle. We conclude that stepping activity in sheep in response to a motion stressor is lateralized, providing evidence that floor motion experienced in transport may induce stress responses.

Trends in Cardiac Mortality in Patients With Locally Advanced Non-Small Cell Lung Cancer

To use the Surveillance, Epidemiology, and End Results (SEER) database to compare cardiac-specific mortality (CSM) between left- and right-sided locally advanced non-small cell lung cancer (LA-NSCLC) patients treated with definitive radiation therapy; and to stratify these patients over fixed time intervals to assess for differences in events by treatment era. The SEER database was queried for patients with stage III NSCLC who received radiation therapy to compare CSM between left- and right-sided primary cases at 5 time intervals: 1988-1992, 1993-1997, 1998-2002, 2003-2007, and 2008-2012. Cumulative incidence of CSM was compared between left- and right-sided patients using Gray's test. The multivariate Fine and Gray competing risk model was used to compare CSM while accounting for other-cause mortality. Of 884,610 lung cancer patients, 52,624 met inclusion criteria; of these, 31,549 (60%) were right-sided and 21,075 (40%) were left-sided. When evaluating CSM in each of the 5 time periods, the overall incidence of CSM decreased over time. There was a statistically significant (P<.05) difference based on laterality in all time periods except 1988-1992 (P=.14). The subdistribution hazard ratio for CSM based on disease laterality in all time periods was 1.30 (95% confidence interval 1.18-1.42) and did not discernibly differ by time interval. On multivariate analysis using the Fine and Gray competing risk model, left-sided laterality independently predicted for CSS from 1993 to 2007 (P<.05). Cardiac-specific mortality has decreased over time, and left-sided disease independently predicted for CSS during 1993-2007 but not 2008-2012. The time course of cardiac mortality seems to be early, consistent with other studies. These findings underscore the importance of minimizing cardiac irradiation during radiation treatment planning.

Trends in cardiac mortality in women with ductal carcinoma in situ.

In certain ductal carcinoma in situ (DCIS) subpopulations, there is no consensus regarding whether to postoperatively irradiate; decisions are often made based on potential risk of cardiac toxicities. Given the utility of Surveillance, Epidemiology, and End Results (SEER) data for studying cardiac mortality in invasive disease, this is the first such study specific for DCIS patients, evaluating trends in cardiac mortality after left-sided radiotherapy (RT). The SEER database was queried for patients with DCIS that received RT and had known unilaterality. The central design of this study was to compare cardiac-specific mortality (CSM) between left- and right-sided DCIS patients as stratifying for "older" RT (1973-1982) versus more "modern" RT (1983-1992 or 1993-2002). Survival analysis was performed using Kaplan-Meier methodology and multivariate Cox regression modeling for factors associated with overall survival (OS) and CSS. Left- and right-sided patients were demographically balanced. CSM was worse for left-sided patients with DCIS diagnosed in 1973-1982 [hazard ratio (HR)1.295; 95% confidence interval (CI) 1.182-1.420], but not in 1983-1992 (HR1.022; 95% CI 0.949-1.100) or in 1993-2002 (HR0.989; 95% CI 0.935-1.046)]. On multivariate analysis, laterality was not associated with OS in either decade. However, left-sided laterality was independently associated with CSM during the 1973-1982 time period, but not the more recent time periods. Examining temporal patterns in the 1973-1982 cohort, cardiac mortality was significantly increased during 10-19 and≥20years after diagnosis, but there was no significant increase in cardiac mortality for patients diagnosed up to 10years after diagnosis. In the largest such DCIS series to date, left-sided RT was an independent risk factor for increased cardiac mortality from 1973 to 1982, but not after 1983. Using modern RT techniques and maintaining low heart doses, RT may not induce excess CSM in the DCIS population.

Left-sided laterality of Merkel cell carcinoma in a German population: more than just sun exposure.

Lateral distribution of cancer has been observed previously. Most evident is this laterality in ultraviolet (UV)-induced skin cancer, based on an unequally distributed UV exposure. The aim of this study was to explore whether patients from Germany also show asymmetrical lateral distribution of Merkel cell carcinoma (MCC). In total, 115 patients with MCC were studied for laterality of the primary tumour. Correlation of clinical variables with lateral distribution of MCC was investigated as well. In 64/115 (55.7%) patients, primary tumours were present on the left side, in 37/115 (32.2%) on the right side, and in 14/115 (12.2%) in the midline (P<0.0001). Excluding the latter localization occurrence of left-sided MCCs (64 of 101/63.4%) was significantly (P=0.0072) more often observed (1.73-fold) when compared to right-sided tumours (37 of 101/36.6%). The excess of left-sided tumours was found on the head with a left-right ratio of 1.8, trunk of 8, arm of 1.2, and leg of 1.8. There was no significant association between laterality and gender, age, MCPyV status, and anatomic localization of primary tumours including the occurrence in sun-exposed sites. Occurrence of left-sided MCCs was significantly more often observed when compared to right-sided tumours. Laterality was not associated with tumour presentation at chronically ultraviolet-exposed sites. Hence, the reason for laterality in MCC remains obscure, but likely goes beyond UV exposure.

The psychological aspects of left-handedness and sinistrality among schoolchildren

Nowadays, there are many schoolchildren who demonstrate a large number of left-sided motor and sensory preferences. It can be considered as external markers of functional hemispheric asymmetry of the brain.The main purpose of the study is to investigate psychological peculiarities and specificity of age-related dynamics of laterality pattern’s formation in junior schoolchildren. The findings show that left-handers differ greatly from right-handed schoolchildren in their mental development by having some peculiarities of intelligence, world’s perception and prevailing thinking strategies, ways of memorization, specificity of emotional-affective expression. As a result they have some educational peculiarities and difficulties. The main problems of left-handed children in school performance are academic failure, lack of perseverance, anxiety neurosis, and extreme emotional lability. Integrated development of left and right hemispheres of left-handed schoolchildren is a favorable condition for their harmonious personal and intellectual development and effective mastering of various modules of the school curriculum. The technological solution of the problem of teaching the children with left-sided laterality is to include in educational programs some special exercises to develop imagination, emotional sensitivity, integrity of perception, global view to the problems, creativeness, and original approaches to tasks’ solving. К eywords: functional asymmetry of the brain; laterality profile; left-handedness; sinistrality; neuropsychology of childhood.

Facial Symmetry: An Illusion?

Objective: To investigate the laterality of the normal asymmetry of the human face, examining differences in laterality in relation to sex, and skeletal classification. Materials and methods: A sample of 120 patients (60 males and 60 females; mean age, 15 years; range, 16-22 years) who had received orthodontic clinical examination at AME’s Dental College and Hospital were selected. Selection was made in such a way that following malocclusions with equal sexual distribution was possible from the patient database. Patients selected were classified into skeletal Class I (25 males and 25 females), Class II (25 males and 25 females) and Class III (10 males and 10 females) based on ANB angle. The number was predecided to be the same and also was based on the number of patients with following malocclusions reported to the department. Differences in length between distances from the points at which ear rods were inserted to the facial midline and the perpendicular distance from the softtissue menton to the facial midline were measured on a frontofacial photograph. Subjects with a discrepancy of more than three standard deviations of the measurement error were categorized as having left- or right-sided laterality. Results: Of subjects with facial asymmetry, 74.1% had a wider right hemiface, and 51.6% of those with chin deviation had left-sided laterality. These tendencies were independent of sex or skeletal jaw relationships. Conclusion: These results suggest that laterality in the normal asymmetry of the face, which is consistently found in humans, is likely to be a hereditary rather than an acquired trait.

Psychological aspects of developing education of children with left-sided laterality

Psychological aspects of developing education of children with left-sided laterality

Laterality of Asymmetry in Movements of the Corners of the Mouth during Voluntary Smile

To examine (1) the laterality of asymmetry in movements of the right and left corners of the mouth in space during voluntary smile and (2) the laterality of asymmetry in relation to the difference between the right and left hemiface size and the handedness. Participants were 155 volunteer Japanese female adults. They were categorized into the symmetric group (n = 120) and the right-side hemiface dominant group (n = 26) according to the hemiface size. In addition, the symmetric group was categorized into the right-handed group (n = 98) and the left-handed group (n = 22) according to the Edinburgh Handedness Inventory. Position vectors of the right and left corners of the mouth were obtained from the three-dimensional facial images for the rest, the maximal lip corner retraction, and the portrait smile. The displacements of the right and left corners of the mouth for each expression and the proportions of the subjects with the right- and left-sided laterality were compared. The left corner of the mouth showed significantly greater displacement (P < .01) than the right in the symmetric group for the portrait smile. The left-sided laterality was found regardless of the handedness. Displacements of the right and left corners of the mouth during voluntary smile were asymmetric, and the left-sided laterality was found. Also, the laterality of the facedness differed in relation to the hemiface size, but was not related to the handedness.

Asymmetry of the Face in Orthodontic Patients

To investigate the laterality of the normal asymmetry of the human face, examining differences in laterality in relation to sex, growth stage, and skeletal classification. A total of 1800 Japanese subjects (651 males and 1149 females; mean age, 15 years 3 months; range, 4 years 2 months to 59 years 11 months) were selected. Individuals in the sample were categorized according to sex, one of three growth stages, and one of three skeletal patterns. Differences in length between distances from the points at which ear rods were inserted to the facial midline and the perpendicular distance from the soft-tissue menton to the facial midline were measured on a frontal facial photograph. Subjects with a discrepancy of more than 3 standard deviations of the measurement error were categorized as having left- or right-sided laterality. Of subjects with facial asymmetry, 79.7% had a wider right hemiface, and 79.3% of those with chin deviation had left-sided laterality. These tendencies were independent of sex, age, or skeletal jaw relationships. In this regard, during pubertal growth, the proportion of subjects with wider right hemiface decreased (P < .0001), whereas the proportion of those with a wider left hemiface increased (P < .01), despite a consistent tendency for right-sided dominance. These results suggest that laterality in the normal asymmetry of the face, which is consistently found in humans, is likely to be a hereditary rather than an acquired trait.

Left-handedness and life span: A reply to Harris.

L. G. Harris's (1993) critique of our hypothesis that left-handedness is associated with a shorter life span (S. Coren & D. F. Halpern, 1991) ignores the supporting statistical evidence, which virtually always shows an increased incidence of left handedness (or other left-sided laterality) associated with a wide range of health risk factors, including serious accidents, immune disorders, early onset breast cancer, alcoholism, smoking, some types of mental retardation, homosexuality, birth-related complications (e.g., resuscitation at birth, extremely low birth weight, Rh incompatibilities, multiple birth, breechbirth, and older maternal age), and selected categories of mental disorders

Hyperactivity and creativity: The tacit dimension

Discriminant analysis was performed on the combined data from two previous studies of high-IQ children with attention disorder and hyperactivity. The variables that best discriminated these from normal children were left-sided laterality, the ability to perceive coherence tacitly, the use of incidentally acquired information, stimulation seeking, and the use of imagery in problem solving and in a creativity task. Regression analysis indicated that figural creativity is best predicted by the ability to perceive relationships tacitly, by good memory for pictured objects, and by verbal creativity. A model was proposed to help explain the functioning of intelligent and creative attention-disordered individuals.

Zur hemispha¨rendominanz fu¨r sprache und rechnen: Elektrophysiologische korrelate einer linksdominanz bei linksha¨ndern

Slow brain potentials were recorded in left-handers and right-handers during: (i) processing of language and mental arithmetic tasks, without vocalization, and (ii) subsequent writing down of the answers with either the right or left hand. Left-sided laterality of negative potentials was taken as evidence of hemispheric dominance. It appeared during the processing of words and numbers in 26 of the 30 left-handers and was localized mainly in the left frontal and temporal parietal regions. Similar results were found with the right-handers. This electrophysiological evidence indicates that the left hemisphere is dominant for language and calculation in the vast majority of left-handers. Only when writing with either their left or right hand do left-handers show less left-sided laterality than right-handers.