Conversational production and comprehension: fMRI-evidence reminiscent of but deviant from the classical Broca-Wernicke model.

A key question in research on the neurobiology of language is to which extent the language production and comprehension systems share neural infrastructure, but this question has not been addressed in the context of conversation. We utilized a public fMRI dataset where 24 participants engaged in unscripted conversations with a confederate outside the scanner, via an audio-video link. We provide evidence indicating that the two systems share neural infrastructure in the left-lateralized perisylvian language network, but diverge regarding the level of activation in regions within the network. Activity in the left inferior frontal gyrus was stronger in production compared to comprehension, while comprehension showed stronger recruitment of the left anterior middle temporal gyrus and superior temporal sulcus, compared to production. Although our results are reminiscent of the classical Broca-Wernicke model, the anterior (rather than posterior) temporal activation is a notable difference from that model. This is one of the findings that may be a consequence of the conversational setting, another being that conversational production activated what we interpret as higher-level socio-pragmatic processes. In conclusion, we present evidence for partial overlap and functional asymmetry of the neural infrastructure of production and comprehension, in the above-mentioned frontal vs temporal regions during conversation.

Multicomponent Velocity Measurement for Linear Sprinting: Usain Bolt's 100 m World-Record Analysis.

The purpose of this report is to provide additional analysis and commentary on the men's 100 m world record of 9.58 s, set by Usain Bolt in the 2009 Berlin World Championships in Athletics. In addition, the entire race underwent a unique kinematic analysis, particularly emphasizing the maximum running velocity and its related factors. It was possible due the application of the new Stuhec software. The data were provided by LAVEG'S advanced laser measurement technology based on positional data with a high spatiotemporal resolution. The maximum velocity phase is the most critical determinant of the final race time. Bolt completed two phases in this world-record 100 m sprint: acceleration and top velocity. The borderline between these phases reached the highest velocity of 12.32 m/s on a 52 m run. He could keep the maximum velocity in five 10 m sections (50-100 m). The occurrence of functional asymmetry-the difference in step length between the left and right legs-was also noticed. Longer steps were taken with the left leg, almost over 80 m. From a practical point of view, new technologies (e.g., software) allow coaches and athletes to analyze the kinematic parameters of sprinting even more precisely and in detail. They must take into account precise changes in the course of maximum speed and the parameters determining it which are step length and frequency. Based on such an analysis, it is possible to modify the training process aimed at increasing the potential, both maximum speed and the supporting factors of strength and power. This must be conditioned by the appropriate selection of training measures shaping the abovementioned motor skills and parameters describing the optimal sprinting technique.

Thalamic regulation of a visual critical period and motor behavior.

During the visual critical period (CP), sensory experience refines the structure and function of visual circuits. The basis of this plasticity was long thought to be limited to cortical circuits, but recently described thalamic plasticity challenges this dogma and demonstrates greater complexity underlying visual plasticity. Yet how visual experience modulates thalamic neurons or how the thalamus modulates CP timing is incompletely understood. Using a larval zebrafish, thalamus-centric ocular dominance model, we show functional changes in the thalamus and a role of inhibitory signaling to establish CP timing using a combination of functional imaging, optogenetics, and pharmacology. Hemisphere-specific changes in genetically defined thalamic neurons correlate with changes in visuomotor behavior, establishing a role of thalamic plasticity in modulating motor performance. Our work demonstrates that visual plasticity is broadly conserved and that visual experience leads to neuron-level functional changes in the thalamus that require inhibitory signaling to establish critical period timing.

Hemispheric Asymmetry of the Hand Motor Representations in Patients with Highly Malignant Brain Tumors: Implications for Surgery and Clinical Practice.

We addressed both brain pre-surgical functional and neurophysiological aspects of the hand representation in 18 right-handed patients harboring a highly malignant brain tumor in the sensorimotor (SM) cortex (10 in the left hemisphere, LH, and 8 in the right hemisphere, RH) and 10 healthy controls, who performed an fMRI hand-clenching task with both hands alternatively. We extracted the main ROI in the SM cortex and compared ROI values and volumes between hemispheres and groups, in addition to their motor neurophysiological measures. Hemispheric asymmetry in the fMRI signal was observed for healthy controls, namely higher signal for the left-hand movements, but not for either patients' groups. ROI values, although altered in patients vs. controls, did not differ significantly between groups. ROI volumes associated with right-hand movement were lower for both patients' groups vs. controls, and those associated with left-hand movement were lower in the RH group vs. all groups. These results are relevant to interpret potential preoperative plasticity and make inferences about postoperative plasticity and can be integrated in the surgical planning to increase surgery success and postoperative prognosis and quality of life.

Flexibility of Ballet Dancers in COVID-19 Pandemic: A Prospective Observational Study in Portugal.

The aim of this study was to verify how dancers' flexibility work has developed during confinement through four assessment moments: before, during (two times), and after the lockdown period. The sample was formed by 18 dancers from the Porto Dance Conservatory (Portugal) with an average age of 11.4 ± 1.4 years and 1.4 ± 0.7 years of experience. To assess the passive and active flexibility level, we used seven of the International Gymnastics Federation's recommended tests using main joints (i.e., hips and spine). The first evaluation was performed before the pandemic situation began in a training environment, and the second and third evaluation were performed during the lockdown, in home environment, and in virtual trainings. Finally, the last evaluation was carried out in a training environment after returning to face-to-face activities and with several rules such a social distancing and mask use. The results showed that significant improvements were verified in the flexibility level of the dancers from the first to the fourth moment of evaluation. In the current study, no statistical significance was noted for the decreased values of functional asymmetry between the preferred and non-preferred lower limbs. These differences may have substantial relevance for dancers' harmonious body development.

[A clinical case of a growing patient with juvenile rheumatoid arthritis of the temporomandibular joint]. / Vedenie rastushchego patsienta s yuvenil'nym revmatoidnym artritom visochno-nizhnechelyustnogo sustava.

BACKGROUND: Treatment of patients with temporomandibular joint pathology in the presence of systemic diseases should include a number of additional methods. OBJECTIVE: The aim of the study to consider an algorithm for providing care to a growing patient with TMJ arthritis on the background of juvenile rheumatoid arthritis complicated by distalization of the mandible. MATERIAL AND METHODS: A growing patient with temporomandibular joint pathology and juvenile rheumatoid arthritis is undergoing complex treatment by a rheumatologist and dentist in order to prevent pronounced degenerative changes in the TMJ bone structures, significant asymmetries of the facial skeleton and the postural component of the patient's body. RESULTS: The patient underwent rehabilitation in order to activate the growth zones, reduce the skeletal asymmetry of the maxillofacial region due to directed growth using conservative techniques. The growth of the branches of the lower jaw was obtained, the optical density of the cortical bone of both condyles improved to the age norm. CONCLUSION: A significant improvement in the prognosis of TMJ rheumatoid arthritis disease in growing patients is possible while creating conditions for adequate interaction of all structures of the maxillofacial region.

Asymmetric Interaction of Neuropeptidase Activities between Cortico-Limbic Structures, Plasma and Cardiovascular Function after Unilateral Dopamine Depletions of the Nigrostriatal System.

In emotional processing, dopamine (DA) plays an essential role, and its deterioration involves important consequences. Under physiological conditions, dopamine exhibits brain asymmetry and coexists with various neuropeptides that can coordinate the processing of brain functions. Brain asymmetry can extend into a broader concept of asymmetric neurovisceral integration, including behavior. The study of the activity of neuropeptide regulatory enzymes (neuropeptidases, NPs) is illustrative. We have observed that the left and right brain areas interact intra- and inter-hemispherically, as well as with peripheral tissues or with physiological parameters such as blood pressure or with behaviors such as turning preference. To obtain data that reflect this integrative behavior, we simultaneously analyzed the impact of left or right brain DA depletion on the activity of various NPs in corticolimbic regions of the left and right hemispheres, such as the medial prefrontal cortex, amygdala and hippocampus, as well as on the plasma activity of the same aminopeptidase activities (APs) and on systolic blood pressure (SBP). Intra- and inter-hemispheric interactions as well as the interactions of NPs from the left or right hemispheres were analyzed with the same plasma APs and the SBP obtained from sham and from left or right lesioned rats. The results demonstrate a complex profile depending on the hemisphere considered. They definitively confirm an asymmetric neurovisceral integration and reveal a higher level of inter-hemispheric corticolimbic interactions including with SBP after left dopamine depletion.

[Crossed aphasia in neurosurgical practice: case report and literature review]. / Perekrestnaya afaziya (Crossed aphasia) v neirokhirurgicheskoi praktike: opisanie sluchaev i obzor literatury.

BACKGROUND: Crossed aphasia in dexstral (CAD) is an extremely rare disorder. To date, about 200 cases have been described in the literature. MATERIAL AND METHODS: The authors report 4 cases of CAD. Luria's neuropsychological examination was carried out. Functional asymmetry in the arm was analyzed using the Annett questionnaire. MRI and intraoperative findings confirmed localization of lesion in the right hemisphere in all patients. RESULTS: A 59-year-old right-handed man developed frontotemporal aphasia after previous resection of right-sided glioblastoma of fronto-insular-temporal region. In a 31-year-old right-handed man, crossed aphasia occurred after extensive hemorrhage from arteriovenous malformation into the right frontotemporoparietal region. A 39-year-old right-handed man developed severe combined aphasia after resection of diffuse glioma of the right insular-temporal region. A 10-year-old right-handed boy developed aphasia with word forgetting after resection of a large tumor of the right temporal lobe. All patients had impaired dynamic praxis. Other cognitive functions were intact. CONCLUSION: The authors discuss possible combinations of functions in one hemisphere for both right-handers and left-handers and emphasize diverse types of functional asymmetries described in the literature. Different localizations of functions in right-handers and left-handers indicate that local zones with different methods of information processing (successive or simultaneous) can coexist in one hemisphere. Therefore, the functions requiring different processing of information (for example, speech with praxis or spatial functions) can develop in one hemisphere. Cognitive impairment depends not only on the type of functional asymmetry, but also on localization of lesion. Crossed aphasia in right-handers indicates the rarest normal type of functional brain asymmetry with localization of speech functions in the right hemisphere. Possible aphasia in right-handers following damage to homologues of speech zones in the right hemisphere can require additional examination of these patients.

Effects of the brain-damaged side after stroke on the learning of a balance task in a non-immersive virtual reality environment.

Background: Post-stroke survivors with right hemisphere injury have more impairments in postural control and balance. However, the impact of the hemisphere injured on the process of balance reacquisition has not been fully explored. We hypothesized that stroke survivors could learn balance tasks (H1), but right hemisphere damaged patients would show poor motor learning if compared to left hemisphere damaged patients (H2)Objective: To investigate whether the brain-damaged side after stroke affects the learning of a balance task. Methods: Three groups were recruited: twenty stroke survivors (ten left and ten right hemisphere damage) and twenty healthy volunteers. The participants practiced a balance task for thirty minutes, four consecutive days. The task was the Table Tilt game (NintendoTM Company), which induces balance demands with a progression of complexity. Motor performance was assessed at baseline, post-practice and after one week (retention test). Accuracy, errors, and complexity of the task achieved during the trial were assessedResults: Participants in all groups improved their performance (p < .001) and maintained it at the retention test. The control group showed better performance if compared to the right and left hemisphere damaged stroke survivors (p < .05). There was no difference between individuals with right and left hemisphere damaged, but the right hemisphere damaged patients demonstrated more errors at higher levels of complexityConclusion: Stroke survivors can learn balance tasks (H1), and the right hemisphere damaged patients demonstrate more errors than those with left hemisphere injury in higher complexity conditions (H2).

Broca's area and the search for anatomical asymmetry: commentary and perspectives.

We present a brief commentary on the field's search for an anatomical asymmetry between Broca's area and its homologue in the non-dominant hemisphere, focusing on a selection of studies, including research from the last decade. We demonstrate that, several years after the influential review of Keller and colleagues from 2009, and despite recent advances in neuroimaging, the existence of a structural asymmetry of Broca's area is still controversial. This is especially the case for studies of the macroanatomy of this region. We point out the inconsistencies in methodology across studies that could account for the discrepancy in results. Investigations of the microstructure of Broca's area show a trend of a leftward asymmetry, but it is still unclear how these results relate to language dominance. We suggest that it may be necessary to combine multiple metrics in a systematic manner to find robust asymmetries and to expand the regional scope of structural investigations. Finally, based on the current state of the literature, we should not rule out the possibility that language dominance may simply not be reflected in local anatomical differences in the brain.

Abnormal Functional Asymmetry in the Salience and Auditory Networks in First-episode, Drug-naive Somatization Disorder.

Evidence of abnormal functional connectivity (FC) has been implicated in patients with somatization disorder (SD). Although the importance of damage to the functional asymmetry has been established, it remains unclear as to whether abnormal intra- and inter-hemispheric FCs are related to patients with SD. We applied resting-state functional magnetic resonance imaging to first-episode, medication-naive patients with SD (n = 25) and matched healthy controls (HCs) (n = 28). The data were analyzed using parameter of asymmetry (PAS) and support vector machine (SVM). Patients with SD showed significantly lower PAS values in the left inferior temporal gyrus (ITG) and higher PAS values in the right insula compared to HCs. A negative correlation was observed between the higher PAS values in the right insula and the Hamilton Depression Scale (HAMD) sleep subscale scores (r = -0.502, p = 0.011), and positive correlations were found between the lower PAS values in the left ITG and the Hamilton Anxiety Scale (HAMA) somatic anxiety subscale scores (r = 0.443, p = 0.027) and the HAMA total scores (r = 0.456, p = 0.022). Moreover, the increased PAS values in the right insula could distinguish patients with SD from HCs with acceptable accuracy (77.36%). First-episode, treatment-naive patients with SD show disrupted asymmetry of inter- and intra-hemispheric FCs. The pattern of disrupted functional asymmetry occurs early in the course of the disease and is independent of medication status, which suggests that disrupted functional asymmetry of salience and auditory networks may be applied as early biological markers for SD.

Functional Laterality of the Lower Limbs Accompanying Special Exercises in the Context of Hurdling.

BACKGROUND: The purpose of this study was to investigate the lateralization of the lead leg during special exercises and the relationship with athletic performance throughout a hurdling session. METHODS: Thirty-eight physical education students participated in the study. A novel three-part "OSI" test (walking over hurdles arranged in a circle, spiral, and straight line) was performed, and various hurdle practices (jogging and running) were selected as research tools. The lead leg selected by the participants was taken into consideration, and the relationship between the chosen lead leg and athletic performance in the five tests was established. RESULTS: The lateralization of the lead leg changed depending on the shape of the running course. The results of further analysis showed (i) no correlation between the use of the right leg as the lead leg in three tests conducted at a marching pace, and (ii) a significant positive correlation between tests performed at the marching and running paces. CONCLUSION: Hurdlers flexibly change the dominant leading leg depending on the shape of the running course. The results of this research could prove helpful in the training of athletes for hurdling competitions, especially young runners in 400-m hurdles involving straight and corner tracks.

Bilateral and ipsilateral peak torque of quadriceps and hamstring muscles in elite judokas.

OBJECTIVE: To examine bilateral and ipsilateral peak torque values of quadriceps (Q) and hamstring (H) muscles in elite judokas. METHODS: 16 elite male judokas were tested in concentric isokinetic strength of the quadriceps (Q) and hamstrings (H) muscles at 60° and 180° sec-1. Variables comprised average peak torque and the traditional H/Q, Q/Q, H/H ratios. Asymmetries between legs and differences between isokinetic muscle strength ratios were examined using paired t-tests and Cohen's d. RESULTS: In right (Rs) and left (Ls) extremity peak torque values, no significant difference was found between 60° and 180° sec-1 angular velocities (p>0.05). In peak torque values between PLs and NPLs, significant difference was found only in extension (Ex) phase at 60° sec-1 angular velocity p=0.001). (Significance was identified between (Q/Q) and (H/H) muscle ratios at 60° sec-1 (p=0.029). No significant difference was found in ipsilateral strength ratios at 60° and 180° sec-1 angular velocity (p>0.05). CONCLUSIONS: The Ex knee strength of PLs was high, particularly at low angular velocities, leading to differences of bilateral asymmetry in the Q muscle group. Regarding ipsilateral strength ratios, there were no differences in the H and Q muscle groups at both angular velocities, indicating that both legs were similar in terms of ipsilateral asymmetry.

Dominant and opponent relations in cortical function: An EEG study of exam performance and stress.

This paper analyzes the opponent dynamics of human motivational and affective processes, as conceptualized by RS Solomon, from the position of AA Ukhtomsky's neurophysiological principle of the dominant and its applications in the field of human electroencephalographic analysis. As an experimental model, we investigate the dynamics of cortical activity in students submitting university final course oral examinations in naturalistic settings, and show that successful performance in these settings depends on the presence of specific types of cortical activation patterns, involving high indices of left-hemispheric and frontal cortical dominance, whereas the lack thereof predicts poor performance on the task, and seems to be associated with difficulties in the executive regulation of cognitive (intellectual) and motivational processes in these highly demanding and stressful conditions. Based on such knowledge, improved educational and therapeutic interventions can be suggested which take into account individual variability in the neurocognitive mechanisms underlying adaptation to motivationally and intellectually challenging, stressful tasks, such as oral university exams. Some implications of this research for opponent-process theory and its closer integration into current neuroscience research on acquired motivations are discussed.

An examination of lower limb asymmetry in ankle isometric force control.

While asymmetries have been observed between the dominant and non-dominant legs, it is unclear whether they have different abilities in isometric force control (IFC). The purpose of this study was to compare ankle IFC between the legs. IFC is important for stabilization rather than object manipulation, and people typically use their non-dominant leg for stabilization tasks. Additionally, studies suggested that a limb can better acquire a motor task when the control mechanism of the task is related to what the limb is specialized for. We hypothesized that the non-dominant leg would better (1) control ankle IFC with speed and accuracy, and (2) acquire an ankle IFC skill through direct learning and transfer of learning. Two participant groups practiced an IFC task using either their dominant or non-dominant ankle. In a virtual environment, subjects moved a cursor to hit 24 targets in a maze by adjusting the direction and magnitude of ankle isometric force with speed (measured by the time required to hit all targets or movement time) and accuracy (number of collisions to a maze wall). Both groups demonstrated similar movement time and accuracy between the dominant and non-dominant limbs before practicing the task. After practice, both groups showed improvement in both variables on both the practiced and non-practiced sides (p < .01), but no between-group difference was detected in the degree of improvement on each side. The ability to control and acquire the IFC skill was similar between the legs, which did not support the brain is lateralized for ankle IFC.

Investigation of left and right lateral fluid percussion injury in C57BL6/J mice: In vivo functional consequences.

Although rodent models of traumatic brain injury (TBI) reliably produce cognitive and motor disturbances, behavioral characterization resulting from left and right hemisphere injuries remains unexplored. Here we examined the functional consequences of targeting the left versus right parietal cortex in lateral fluid percussion injury, on Morris water maze (MWM) spatial memory tasks (fixed platform and reversal) and neurological motor deficits (neurological severity score and rotarod). In the MWM fixed platform task, right lateral injury produced a small delay in acquisition rate compared to left. However, injury to either hemisphere resulted in probe trial deficits. In the MWM reversal task, left-right performance deficits were not evident, though left lateral injury produced mild acquisition and probe trial deficits compared to sham controls. Additionally, left and right injury produced similar neurological motor task deficits, impaired righting times, and lesion volumes. Injury to either hemisphere also produced robust ipsilateral, and modest contralateral, morphological changes in reactive microglia and astrocytes. In conclusion, left and right lateral TBI impaired MWM performance, with mild fixed platform acquisition rate differences, despite similar motor deficits, histological damage, and glial cell reactivity. Thus, while both left and right lateral TBI produce cognitive deficits, laterality in mouse MWM learning and memory merits consideration in the investigation of TBI-induced cognitive consequences.

Differential sensitivity to changes in pitch acceleration in the auditory brainstem and cortex.

The cortical pitch-specific response (CPR) is differentially sensitive to pitch contours varying in rate of acceleration-time-variant Mandarin Tone2 (T2) versus constant, linear rising ramp (Linear)-as a function of language experience (Krishnan, Gandour, & Suresh, 2014). CPR and brainstem frequency following response (FFR) data were recorded concurrently from native Mandarin listeners using the same stimuli. Results showed that T2 elicited larger responses than Linear at both cortical and brainstem levels (CPR: Na-Pb, Pb-Nb; FFR). However, Pb-Nb exhibited a larger difference in magnitude between T2 and Linear than either Na-Pb or FFR. This finding highlights differential weighting of brain responses elicited by a specific temporal attribute of pitch. Consistent with the notion of a distributed, integrated hierarchical pitch processing network, temporal attributes of pitch are differentially weighted by subcortical and cortical level processing.

Longitudinal Study of the Emerging Functional Connectivity Asymmetry of Primary Language Regions during Infancy.

Asymmetry in the form of left-hemisphere lateralization is a striking characteristic of the cerebral regions involved in the adult language network. In this study, we leverage a large sample of typically developing human infants with longitudinal resting-state functional magnetic resonance imaging scans to delineate the trajectory of interhemispheric functional asymmetry in language-related regions during the first 2 years of life. We derived the trajectory of interhemispheric functional symmetry of the inferior frontal gyrus (IFG) and superior temporal gyrus (STG), the sensory and visual cortices, and two higher-order regions within the intraparietal sulcus and dorsolateral prefrontal cortex. Longitudinal models revealed a best fit with quadratic age terms and showed significant estimated coefficients of determination for both the IFG (r2 = 0.261, p < 0.001) and the STG (r2 = 0.142, p < 0.001) regions while all other regions were best modeled by log-linear increases. These inverse-U-shaped functions of the language regions peaked at ∼11.5 months of age, indicating that a transition toward asymmetry began in the second year. This shift was accompanied by an increase in the functional connectivity of these regions within the left hemisphere. Finally, we detected an association between the trajectory of the IFG and language outcomes at 4 years of age (χ2 = 10.986, p = 0.011). Our results capture the developmental timeline of the transition toward interhemispheric functional asymmetry during the first 2 years of life. More generally, our findings suggest that increasing interhemispheric functional symmetry in the first year might be a general principle of the developing brain, governing different functional systems, including those that will eventually become lateralized in adulthood. SIGNIFICANCE STATEMENT: Cross-sectional studies of the language system in early infancy suggest that the basic neural mechanisms are in place even before birth. This study represents the first of its kind, using a large longitudinal sample of infants, to delineate the early language-related transition toward interhemispheric functional asymmetry in the brain using resting-state functional MRI. More generally, our findings suggest that increasing interhemispheric functional symmetry in the first year might be a general principle of the developing brain governing multiple functional systems, including those that will eventually become lateralized in adulthood. Although resting-state functional MRI cannot provide direct insights into the developmental mechanisms of language lateralization, this study reveals language-related functional connectivity changes during infancy, marking critical points in the development of the brain's functional architecture.

Terminal Duplex Stability and Nucleotide Identity Differentially Control siRNA Loading and Activity in RNA Interference.

Efficient short interfering RNA (siRNA)-mediated gene silencing requires selection of a sequence that is complementary to the intended target and possesses sequence and structural features that encourage favorable functional interactions with the RNA interference (RNAi) pathway proteins. In this study, we investigated how terminal sequence and structural characteristics of siRNAs contribute to siRNA strand loading and silencing activity and how these characteristics ultimately result in a functionally asymmetric duplex in cultured HeLa cells. Our results reiterate that the most important characteristic in determining siRNA activity is the 5' terminal nucleotide identity. Our findings further suggest that siRNA loading is controlled principally by the hybridization stability of the 5' terminus (Nucleotides: 1-2) of each siRNA strand, independent of the opposing terminus. Postloading, RNA-induced silencing complex (RISC)-specific activity was found to be improved by lower hybridization stability in the 5' terminus (Nucleotides: 3-4) of the loaded siRNA strand and greater hybridization stability toward the 3' terminus (Nucleotides: 17-18). Concomitantly, specific recognition of the 5' terminal nucleotide sequence by human Argonaute 2 (Ago2) improves RISC half-life. These findings indicate that careful selection of siRNA sequences can maximize both the loading and the specific activity of the intended guide strand.

Asymmetric interference in left-handers during bimanual movements reflects switch in lateralized control characteristics.

Interactions between the hands are a collateral of simultaneous bimanual movements and can inform us about the functional asymmetries of the dominant and nondominant hemisphere-effector systems. Few studies on bimanual coordination have focused on discrete movement control, and even fewer have looked at this in the context of handedness. Using a novel bimanual paradigm in which both hands perform simultaneous target-directed movements, this study addressed interference between the hands in two groups of left-handed individuals. In one group, the dominant hand was perturbed, and in the other, the nondominant hand; the respective contralateral hand moved without visual feedback. Results show that the kinematic perturbation of the dominant left hand resulted in directional interference in the nonvisible right hand. Similarly to previous studies using this bimanual paradigm, interference became manifest through isodirectional deviations in the nonvisible hand in the majority of participants. The findings mirror the results of a previous study in right-handers. At the same time, interference was overall weaker in the left-handers, and not as exclusively dominant to nondominant as in the previous right-handed sample. The results not only confirm that hand control characteristics switch with handedness, but also shape interactions between the hands accordingly in left-handers.