Right-handed Persons Research Articles

Effects of handedness on brain oscillatory activity during imagery and execution of upper limb movements.

Brain activation during left- and right-hand motor imagery is a popular feature used for brain-computer interfaces. However, most studies so far have only considered right-handed participants in their experiments. This study aimed to investigate how handedness influences brain activation during the processes of imagining and executing simple hand movements. EEG signals were recorded using 32 channels while participants repeatedly squeezed or imagined squeezing a ball using their left, right, or both hands. The data of 14 left-handed and 14 right-handed persons were analyzed with a focus on event-related desynchronization/synchronization patterns (ERD/S). Both handedness groups showed activation over sensorimotor areas; however, the right-handed group tended to display more bilateral patterns than the left-handed group, which is in contrast to earlier research results. Furthermore, a stronger activation during motor imagery than during motor execution could be found in both groups.

Tα οφέλη της γραφής με το χέρι στην ανάπτυξη της αναγνωστικής ικανότητας: ανασκόπηση νευροαπεικονιστικών ευρημάτων

Although reading and writing are often treated as two separate processes, the research data of recent years suggest that these two functions seem to be interrelated and one depends on the other. The aim of this study was to examine whether handwriting is related to and, further, influences the development of reading abilities. To this end, we have reviewed neuroimaging research conducted over the last fifteen years. Research findings, both for pre-school and early-school children, as well as for adults, showed that handwriting influences brain development and activates brain reading systems more than other sensory kinetic techniques. Neuroimaging revealed that learning to write is based on the development of a network of brain structures, which includes the dorsal premotor cortex, the ventral premotor cortex, the upper parietal cortex and the fusiform gyrus of the left hemisphere in right-handed persons, as well as the contralateral cerebellum, structures whose participation and interconnection are specific to the writing of alphabet characters. This network is structured for the common learning of writing and reading and depends on the level of the writer's experience. The perception of letters is helped by the handwriting experience, upon which the ability to process the letters in the person's brain during reading is also based. The brain networks that appear to be triggered when identifying letters following the learning of these letters through handwriting are the same sensory kinetic networks that are activated during letter recognition and reading. In conclusion, the sensory experience gained through handwriting seems to develop the brain and strengthens the person’s ability to read.

Overconfidence and the 2D:4D ratio

This paper tests whether prenatal testosterone levels are related to overconfidence. We use a non-intrusive method called 2D:4D ratio to measure prenatal exposure to testosterone of subjects. Using data collected from students from a large university in Brazil, we find that testosterone is positively correlated with higher levels of overconfidence. We also find support that males and self-declared white persons are associated to higher overconfidence levels comparatively to females and self-declared non-white persons, respectively. We also find that the marginal effect of prenatal testosterone on overconfidence is higher for left-handed than for right-handed persons. This means that the role of the prenatal testosterone, as measured by the 2D:4D ratio, on overconfidence is more relevant to left-handed persons. Our work presents empirical evidence that prenatal testosterone is an important predictor of individuals’ overconfidence behavior and that biological traits either attenuate or exacerbate such relationship.

Relationship between dominant hand and ear preference for listening among medical students

Objective: The aim of the study was to determine dominant hand for routine activities and ear preference for listening among medical students. Mobile phone usage was also studied. Methodology: Medical students of three batches (2nd, 3rd, and 4th year) studying in a government medical college of Delhi (India) were considered. Out of 150 permitted (50 per batch) seats, only 139 were filled. Thus, after seeking an informed consent, a total of 117 (84.1%) available students could be contacted in person who completed the survey capturing details such as Section-I: Sociodemographic background; Section-II: Dominant hand (right/left) for undertaking routine activities, ear (right/left) preference for listening say mobile phones; and Section-III: Selected details of their mobile phones. Results: There were 71 (60.7%) males and 46 (39.3%) female students; It was found out that out of 117 students, 110 (94.0%) were right handed while 7 (5.9%) were left handed. Out of all the right-handed persons (n = 110), 94 (85.4%) preferred right ear, 14 (12.7%) left ear, and 2 (1.8%) either of the ears for listening phone. Similarly, out of all the left-handed persons (n = 07), 6 (85.7%) preferred left ear and only 1 (14.2%) right ear for listening mobile phone. Right-sided (right hand-right ear) laterality was observed in 85.4% and left-sided (left hand-left ear) laterality in 85.7% with overall (same hand-same ear) laterality of 85.4% among study participants (P

Asymmetrical Electroencephalographic Change of Human Brain During Sleep Onset Period.

ObjectiveHuman cerebral hemisphere is known to function asymmetrically with daytime left hemisphere superiority in most right-handed persons. It may have relevance to the localization of specific function of the brain. This study attempted to reveal whether the functional cerebral asymmetry in the wakeful state is still maintained throughout the sleep onset period.MethodsThirty-channel EEG was recorded in 61 healthy subjects. The EEG power spectra of each of the seven frequencies were compared between the two kinds of 30-second states; the wakeful stage and the late-sleep stage 1.ResultsThe asymmetrical indices of sleep stage 1 at several fronto-central leads were decreased in the delta, theta, alpha-2, and all beta bands. Conversely, at parts of parieto-occipital leads showed an increase in the indices of the theta, alphas, beta-1, and beta-2 bands. Any fronto-central leads did not show an increase in the index, and no parieto-occipital leads showed a decrease.ConclusionDuring the sleep onset period, power spectral asymmetry of the brain showed a different pattern from the wakeful stage. This asymmetrical pattern of EEG powers may suggest a reversal of the left hemispheric dominance during sleep.

Abnormal interhemispheric resting state functional connectivity of the insula in heroin users under methadone maintenance treatment

Abnormal interhemispheric functional connectivity is attracting more and more attention in the field of substance use. This study aimed to examine 1) the differences in interhemispheric functional connections of the insula with the contralateral insula and other brain regions between heroin users under methadone maintenance treatment (MMT) and healthy controls, and 2) the association between heroin users' interhemispheric insular functional connectivity using resting functional magnetic resonance imaging (fMRI) and the results of urine heroin analysis. Sixty male right-handed persons, including 30 with heroin dependence under MMT and 30 healthy controls, were recruited to this study. Resting fMRI experiments and urine heroin analysis were performed. Compared with the controls, the heroin users had a significantly lower interhemispheric insular functional connectivity. They also exhibited lower functional connectivity between insula and contralateral inferior orbital frontal lobe. After controlling for age, educational level and methadone dosage, less deviation of the interhemispheric insula functional connectivity was significantly associated with a lower risk of a positive urine heroin analysis result. Our findings demonstrated that the heroin users under MMT had abnormal long-range and interhemispheric resting functional connections. Those with a less dysfunctional interhemispheric insula functional connectivity had a lower risk of a positive urine heroin test.

Remodeling of cortical activity for motor control following upper limb loss.

Upper extremity loss presents immediate and lasting challenges for motor control. While sensory and motor representations of the amputated limb undergo plasticity to adjacent areas of the sensorimotor homunculus, it remains unclear whether laterality of motor-related activity is affected by neural reorganization following amputation. Using electroencephalography, we evaluated neural activation patterns of formerly right hand dominant persons with upper limb loss (amputees) performing a motor task with their residual right limb, then their sound left limb. We compared activation patterns with left- and right-handed persons performing the same task. Amputees have involvement of contralateral motor areas when using their sound limb and atypically increased activation of posterior parietal regions when using the affected limb. When using the non-amputated left arm, patterns of activation remains similar to right handed persons using their left arm. A remodeling of activations from traditional contralateral motor areas into posterior parietal areas occurs for motor planning and execution when using the amputated limb. This may reflect an amputation-specific adaptation of heightened visuospatial feedback for motor control involving the amputated limb. These results identify a neuroplastic mechanism for motor control in amputees, which may have great relevance to development of motor rehabilitation paradigms and prosthesis adaptation.

Cortical reorganization for calculation in patients with left temporal lobe epilepsy

Objective To observe the brain regions activated during calculation in patients with left temporal lobe epilepsy (TLE) and in normal subjects. Methods Functional magnetic resonance imaging (fMRI) was applied. Sixteen right-handed persons with left TLE were selected as the left TLE group, and sixteen healthy volunteers were recruited as a control group. The fMRI data was collected as each subject performed simple additions, subtractions and abdication subtractions. Statistical parametric mapping was used to compare the activated brain regions between the two groups. Results The error rate in the calculations was significantly higher in the left TLE group, and their average reaction time was significantly longer. There were aslo significant differences between the two groups in terms of brain activation patterns. Compared with the control group, the left TLE group exhibited hypo-activity in regions such as the left paracentral lobule, the posterior central gyrus, the bilateral inferior parietal lobule, the left angular gyrus, the bilateral supramarginal gyrus, the left middle frontal gyrus, the left superior gyrus, and also in the bilateral posterior cingulate, insular lobule, superior and inferior temporal gyrus, right hippocampus, parahippocampal gyrus, thalamus and cerebellum. The TLE subjects exhibited hyper-activity in the bilateral superior parietal lobule, the bilateral anterior cingulate, as well as in the right, middle and inferior frontal gyrus. Conclusion Our results support a significant functional reorganization of calculation-related neuronal networks within and between the hemispheres in TLE patients. The frontal and parietal lobes may play a compensatory role in the reorganization of the calculation function. Task-related fMRI technology can provide useful information for non-invasive assessment of mathematical computing and cognitive function in TLE patients. Key words: Temporal lobe epilepsy; Computation; Cognition; Functional magnetic resonance imaging

Lexico-semantic deficits in people with right hemisphere damage: Evidence from convergent naming tasks

Abstract The right hemisphere (RH) continues to attract considerable scientific attention on its word processing skills. Despite extensive research in this direction, consensus on this issue is lacking. In this context, the present study explored the influence of right hemisphere damage (RHD) on word retrieval (i.e., oral naming) tasks. We administered a battery of 10 convergent naming tasks on a group of 22 right-handed persons with RHD as well as on an equal number of neurotypical age-, gender-, handedness-, and literacy-matched (i.e., control) participants. The comparison of accuracy scores and errors obtained from the two groups revealed significantly poorer performance in the RHD group except on one task (i.e., definition-naming). Additionally, analysis of errors revealed a preponderance of semantic errors. These findings support the role of the right hemisphere in word processing.

Taping of the elbow extensor muscle in chronic stroke patients: comparison between before and after three-dimensional motion analysis.

[Purpose] This study aimed to observe the effect of kinesio taping on the quality of movement of each arm during a reaching task in patients with right-sided hemiparetic stroke. [Subjects and Methods] Sixteen right-handed participants who had had a right-sided hemiparetic stroke were requested to perform a reaching task with each arm, with and without kinesio taping. A three-dimensional motion analysis system was used to measure peak angular velocity, time to reach peak angular velocity, and movement units during elbow motion. [Results] In the right arm, movements during the reaching task with kinesio taping were faster, smoother, and more efficient than those without kinesio taping. The peak angular velocity increased, and the time to reach peak angular velocity decreased. Movement units decreased significantly. However, in the untaped arm, the movement was slower, rougher, and less efficient. [Conclusion] Kinesio taping provided a positive effect on the reaching movement of the taped arm of right-handed persons who had had a right-sided hemiparetic stroke.

3D motion analysis comparison of left handers' wrist flexion and cutting accuracy according to scissors type.

[Purpose] The purpose of this study was to research the difference in wrist flexion and accuracy of left-handers when using regular scissors made for right-handed persons versus scissors made for left-handers. [Subjects and Methods] Eighteen left-handers participated in the experiment. There were ten males and eight females subjects. The degree of wrist flexion of 18 left-handers was analyzed when using scissors designed for left-handers and when using scissors designed for right-handers. [Results] When left-handers used left-handed scissors, they carried out the task while extending the wrist at 4.67±14.60°, but when they used right-handed scissors, they carried out the task while flexing the wrist at 1.19±12.41°. When left-handers used left-handed scissors, the error rate was 1.39±1.29 times on average, but when they used right-handed scissors, the rate was 0.72±0.67 times on average. [Conclusion] When left-hand dominant persons used left-handed scissors rather than right-handed scissors, the degree of wrist flexion decreased, which created more functionality, and the accuracy of the cutting increased. For improved cutting accuracy and wrist stability and to protect the wrist from extensive flexion, it is necessary for left-handers to use scissors that are made for left-handed people.

DYNAMICS OF FUNCTIONAL INTERHEMISPHERIC ASYMMETRY AND PARTICULARITIES OF VARIABILITY OF THE CARDIAC RHYTHM IN CHILDREN OF 7-8 YEARS IN THE INFORMATION LOAD

During the information loading in children, the changes of coefficient of functional asymmetry, reflecting strengthening role of left hemisphere in realization of mental activity in the age of 7 to 8 years are revealed. At the same time, shifts of diagnostic parameters of variability of cardiac rhythm depending on age, sex and direction of changes in coefficient of asymmetry are found. Most pronounced changes were found in indexes of activity of sympathetic and parasympathetic nervous system, thus more noticeable change by sympathetic nervous system at loading was observed in girls of the first class, and parasympathetic — in boys of the second class. Dependence of changes of coefficient of functional asymmetry at loading of reference values is established in sympathetic nervous system and Bayevsky index at right-handed persons of 8 years.

Структурно-функциональные особенности работы мозга при выполнении и представлении двигательных нагрузок у здоровых людей (ЭЭГ и фМРТ исследования)

Bioelectrical (EEG) and hemodynamic (fMRI-response) cerebral reactions to performance and imaginary motor tasks by right or left hand were analyzed in 15 right-handed healthy persons (21-39 years old). During actual movement the main fMRI-response was registered in the area of central gyrus of the hemisphere contralateral to the working hand. Areas of activation were also revealed in the supplemental motor area and the ipsilateral hemisphere of the cerebellum. EEG data showed coherence increase in high frequency alpha- and beta-bands in the activated hemisphere. In imaginary motor tasks the intensity and topography of fMRI-response became the more variable; response was decreased in the motor area and in cerebellum, they increased in the subcortical structures and in the parietal association zones. EEG changes were very variable in this situation also; it was observe an increase of EEG coherence in the right hemisphere for higher frequency of alpha and beta spectral bands. Changes of power spectrum parameters were similar to performance and imaginary motor tasks. Spectrum power and middle frequency of beta band were increased. Topographically these changes did not correspond to activated hemisphere and it was more in the left hemisphere. These changes were reflected nonspecific component of reaction.

Enhanced Left-Finger Deftness Following Dominant Upper- and Lower-Limb Amputation

Background. After amputation, the sensorimotor cortex reorganizes, and these alterations might influence motor functions of the remaining extremities. Objective. The authors examined how amputation of the dominant or nondominant upper or lower extremity alters deftness in the intact limbs. Methods. The participants were 32 unilateral upper- or lower-extremity amputees and 6 controls. Upper-extremity deftness was tested by coin rotation (finger deftness) and pegboard (arm, hand, and finger deftness) tasks. Results. Following right-upper- or right-lower-extremity amputation, the left hand’s finger movements were defter than the left-hand fingers of controls. In contrast, with left-upper- or left-lower-extremity amputation, the right hand’s finger performance was the same as that of the controls. Conclusions. Although this improvement might be related to increased use (practice), the finding that right-lower-extremity amputation also improved the left hand’s finger deftness suggests an alternative mechanism. Perhaps in right-handed persons the left motor cortex inhibits the right side of the body more than the right motor cortex inhibits the left side, and the physiological changes induced by right-sided amputation reduced this inhibition.

Morphogenetic variability and handedness in Montenegro and Serbia

This study tries to establish correlations between the types of handedness and several morpho-physiological characteristics, controlled by one or a small number of genes with alternative dominant recessive manifestation. The population-genetic homozygosity degree study includes the analysis of the presence, distribution and individual traits combination in left-handed and right-handed persons. It was conducted at three localities in two states, Serbia (SRB) and Montenegro (MNE). Our hypothesis is that a possible genetic load due to increased recessive homozygosity, being a potential population-genetic parameter of left-handedness manifestation, may cause some change in other morpho-physiological characters. The average proportion of 23 studied homozygously-recessive characters (HRC's) was similar among observed left-handed individuals in the studied localities. It varied from 10.5 +/- 0.4 in Serbia to 10.7 +/- 0.3 in MNE. The differences were somewhat bigger among right-handed persons, varying from 8.7 +/- 0.3 in MNE to 9.1 +/- 0.3 HRC's in Serbia. However, in all localities the average homozygosity was significantly higher among left-handed school children. The number of HRC's among 400 individuals varied from 2 to 16 among right-handed and from 4 to 19 among left-handed persons. There were no differences in scholar scores between left-handed and right-handed children, although small differences were found between two state samples.

Augmentation effect of repetitive transcranial magnetic stimulation over the supplementary motor cortex in treatment refractory patients with obsessive compulsive disorder

Background:There are only a few effective treatment options currently available for treatment-refractory obsessive compulsive disorder (OCD). The supplementary motor area (SMA) has been reported to play an important role in the pathophysiology of OCD. Functional neuroimaging studies indicate that OCD is associated with increased activity in the SMA, caudate nucleus, and anterior cingulate gyrus. Novel treatment strategies like repetitive transcranial magnetic stimulation (rTMS) have been proposed for OCD refractory to standard treatments. These clinic-based data report on the efficacy of rTMS in medication-resistant OCD.Materials and Methods:Twelve right-handed persons with medication-resistant OCD were administered rTMS as an add-on treatment. Stimulation was given at 1 Hz for 10 seconds followed by 15 seconds pause and 100 trains of stimulus over the SMA per session for 5 days in a week. Assessments were done on yale brown obsessive compulsive scale (Y-BOCS) at baseline and at the end of rTMS intervention.Results:The subjects had a mean age of 33.17±12.74 years. Mean scores on Y-BOCS were 26.17 at baseline and 17.17 at the end of treatment, reflecting significant improvement. The subjects did not report any significant side effects except one person with known bipolar illness, who developed manic symptoms after the 3rd session of the rTMS.Conclusions:Low-frequency rTMS over the SMA appears a promising treatment strategy as an add-on treatment in treatment-refractory patients of OCD.

Afasias e áreas cerebrais: argumentos prós e contras à perspectiva localizacionista

O objetivo do presente estudo foi investigar como áreas corticais comprometidas por um acidente vascular encefálico (AVE) estão relacionadas com os diferentes tipos de afasia, visto que há controvérsias com relação à localização da lesão no cérebro e as características dos quadros de alteração da linguagem. Foram avaliados 26 indivíduos destros, portadores de lesão cérebro-vascular esquerda e de sintomas afásicos, através do protocolo de Montreal-Toulose, módulo standard inicial - versão alpha, que inclui provas de nomeação, repetição, compreensão oral, compreensão escrita e leitura, e de uma entrevista, que possibilitou a avaliação da fluência do discurso. Os sujeitos foram divididos em quatro subgrupos, de acordo com o sítio de lesão: frontal, temporal, têmporo-parietal e parietal/ parieto-occipital. Os dados foram submetidos a uma análise multidimensional (Similarity Structure Analysis [SSA]) e o método das variáveis externas como pontos. Os resultados revelaram uma correlação positiva alta entre lesão na área frontal e o acometimento da fluência no discurso, assim como correlações positivas altas entre lesão no lobo temporal e prejuízos em todas as habilidades avaliadas no teste: nomeação, repetição, compreensão oral, compreensão escrita e leitura, o que, até certo ponto, corrobora as idéias de estudos localizacionistas, na medida em que estabelece o papel preponderante do lobo temporal para a linguagem e a importância do lobo frontal para as praxias da fala. No entanto, nos demais subgrupos, têmporo-parietal e parietal/ parieto-occipital, se observou correlações positivas apenas com a compreensão oral e com a repetição, essa última somente no segundo grupo e com índice baixo, e correlações negativas altas com a fluência no discurso, o que sugere que esta habilidade se manteve preservada nestes grupos e fragiliza o argumento localizacionista.

Prevalence of the palmaris longus in relation to the hand dominance

The incidence of left-handedness in the general population is between 8 and 15%. There is a presumption that the prevalence of palmaris longus muscle differ between right-handed and left-handed people. This prospective study was conducted to determine the prevalence of the palmaris longus in relation to the hand dominance. The study included 542 subjects (216 male and 326 female). They were initially tested to hand dominance and after that they were asked to do the standard test (Schaeffer's test) for the assessment of the palmaris longus tendon. If the tendon was not visualized or palpable, four additional tests (Thompson's test, Mishra's tests I and II, Pushpakumar's "two-finger sign" method) were done to confirm its absence. Right hand dominance was recorded in 452 (83.4%) subjects while the left hand dominance was recorded in 90 (16.6%) subjects. In right-handed subjects, palmaris longus tendon was absent on the right side in 24 (5.3%) and on the left side in 50 (11.1%) cases. In left-handed subjects, it was absent on the right side in 18 (20%) and on the left side in 2 (2.2%) cases. These differences were statistically significant. Bilateral absence of palmaris longus tendon was similar in both examined groups (25.1% in the overall series, 24.3% in right-handed subjects, 28.9% in left-handed subjects). The results of our study show that a right-sided absence was more common in left-handed persons while the left-sided absence was more common in right-handed persons. Unilateral tendon absence was more common on the non-dominant hand.

What Does Left Hand Know That Right Hand Doesn't?

What Does Left Hand Know That Right Hand Doesn't?

Neurology of cognition and language in the publications of Kálmán Sántha and today

Based on histopathological investigation of the brain of exceptionally talented persons Sántha found increased volume of parietal association areas with abundance of cells. He supposed that the angular gyrus may be a "memory field". In his publication Genius and inheritance he expressed that: "Talent is a child of the present, but the genius is born for eternity." He discussed the localization of sensory and motor amnestic aphasia analysing the signs of patient with brain tumor and called attention to concomitant psychological symptoms. He found crossed aphasia in twice as many lefthanded than righthanded persons. This may explain the recent observations that the restitution of aphasia is predetermined; speech ability of ambidexterous or latent lefthanded persons improve better. He analysed the topography of emotional and voluntary facial palsy. The currently accepted hierarchical concept of mental and speech ability can be derived from the ouevre of Sántha and his predecessors. Sántha can be honoured as a forerunner of the modern theories of aphasia localization.