Right-handed Individuals Research Articles

Consideration of handedness in human-robot collaboration

In the design of assembly workplaces, considerations regarding handedness and ergonomics play a crucial role. The emergence of human-robot collaboration presents an innovative avenue for enhancing the ergonomic aspects of manual assembly tasks. While initial applications have demonstrated improvements in lifting and holding activities, they often overlook the influence of human handedness. This paper advocates for the adoption of adaptive assembly processes, which offer simple and intuitive robot programming options to enhance workflow efficiency and reduce stress. This study is grounded in two investigations conducted at the Bremen Institute for Mechanical Engineering. The first study, a pilot investigation, aimed to identify indicators of the influence of handedness and ergonomics, laying the groundwork for further research. Building upon these findings, the second study delves into the interaction between workers and collaborative robots during assembly operations. Data collected from 50 participants form the basis for statistical analysis, providing insights into performance factors and self-assessment, as well as external evaluations of ergonomics. A notable finding of this study challenges the assumption of mirrored behavior between presumed left-handed and right-handed individuals. Additionally, the study identifies a subgroup of participants with ambiguous handedness, suggesting a lack of training in their natural handedness. Through these investigations, this paper contributes to our understanding of the intricate relationship between handedness, ergonomics, and human-robot collaboration in assembly workplaces. By addressing these factors comprehensively, we can pave the way for the development of more inclusive and efficient assembly processes.

Relationship between musculoskeletal discomfort and cell phone use among young adults: A cross-sectional survey.

Cell phone usage is highly prevalent among young adults. They are used for multiple purposes including communication, studies, social networking and entertainment. However, its excessive usage has been associated with adverse health outcomes. The objective was to find the association of cell phone usage with musculoskeletal discomfort (MSD) and its associated factors. A cross-sectional study was conducted on young adult students from a low-middle income country over a period of 3 months from December 2018 to February 2019. A structured questionnaire based on the Disabilities of the Arm, Shoulder and Hand (QuickDASH scoring) was used to record the musculoskeletal discomfort. Out of 803 questionnaires, data of 754 (94%) were entered and the remaining questionnaires (n = 49) were discarded due to incomplete answers. The mean age was 20.83 (1.62) years. In our study, there were 194 (25.7%) males and 560 (74.3%) female participants. Neck and shoulder were the most frequently affected regions. A significant difference in QuickDASH score was observed between genders (p-value p ≤ 0.001). Left-handed individuals scored significantly higher on QuickDASH score compared to right-handed individuals (p < 0.05). Increased musculoskeletal discomfort was reported by individuals with daily cell phone use of more than four hours (p < 0.05). A positive significant correlation was found between continuous one hour cell-phone use and higher mean QuickDASH scores (correlation coefficient 0.124, p value 0.001). Shorter eye-to-screen distance was significantly associated with MSD (p < 0.05). Musculoskeletal discomfort is associated with the female gender, duration of cell phone use and a small eye-to-screen distance.

Evidence of increased cardiovascular disease risk in left-handed individuals.

Approximately 10% of the world is left-handed (LH). Research suggests that LH individuals may have shorter lifespans compared to right-handed (RH) individuals. LH individuals also appear to have more cardiovascular disease (CVD) related conditions like diabetes and cancer. Thus, the present study sought to test the hypothesis that vascular function and heart rate variability (HRV), both key indicators of CVD risk, would be lower in LH compared to RH individuals. Three hundred seventy-nine participants, 18-50 years old, were enrolled. Flow-mediated dilation (FMD), a bioassay of vascular endothelial function and standard deviation of R-R interval (SDNN), a parameter of HRV, were evaluated as indices of CVD risk. Data are reported as mean ± SD. 12.1% of the participants were LH. No differences in demographics or clinical laboratory values were observed between groups, except high-density lipoprotein (HDL) was higher (p = 0.033) in RH. FMD was significantly (p = 0.043) lower in LH (6.1% ± 3.2%) compared to RH (7.6% ± 3.8%), independent of age, sex, race, BMI, and HDL. Total power (p = 0.024) and low-frequency power (p = 0.003) were lower in LH compared to RH. Additionally, SDNN was lower (p = 0.041) in LH (47.4 ± 18.8 ms) compared to RH (54.7 ± 22.3 ms). A negative correlation between FMD and mean arterial pressure (r = -0.517; p < 0.001) was observed in LH; no relationships were observed in RH (all p > 0.05). Vascular endothelial function and HRV are lower in LH compared to RH. In addition, relationships between FMD and traditional CVD risk factors were only observed in LH. These data support an increased risk of CVD in LH.

Right or left-handed: are locomotion type, body size, and microhabitat related to forelimb laterality in anurans?

Laterality, the tendency of animals to use the structures on one side of the body more frequently or efficiently than the other side, can reflect the evolutionary history of species, their ecological characteristics, and cognitive abilities. Using anurans as a model system, it has been hypothesized that the strength of laterality (measured as the percentage of right-handed individuals) is higher in terrestrial and arboreal species, which exhibit asynchronous locomotion type (e.g., walking, climbing), than in aquatic species where synchronous locomotion type (e.g., swimming) predominates. We tested these predictions, including body size as an additional factor, in 19 Neotropical anuran species. For this, we obtained data on forelimb use preference for individuals of such species. We then combined these data with published data for another 14 anuran species obtained through a systematic review of the literature. The combined dataset was used to perform a phylogenetic comparative analysis to verify the strength of laterality in the species. We found that four out of the 19 tested species show a percentage of right-handed individuals that was higher or lower than expected by chance. Individuals of these four species exhibit asynchronous movements of forelimbs during displacements, foraging behaviors, sexual displays, or agonistic interactions. Results of a phyloANOVA and a phyloANCOVA indicated that the strength of laterality was higher in species with asynchronous movements, but this was unrelated to microhabitat and body size. Asynchronous (i.e., non-simultaneous) movements of limbs imply alternating muscle contractions and a higher neural asymmetry than synchronous (i.e., simultaneous) movements of limbs. Therefore, species with an asynchronous locomotion type could be reflecting such complexity and neural asymmetry in higher levels of forelimb laterality. Our results mostly support the predictions based on models that cover the expected relationship between the strength of laterality and the evolutionary ecology of vertebrates.

The functional organization of skilled actions in the adextral and atypical brain

When planning functional grasps of tools, right-handed individuals (dextrals) show mostly left-lateralized neural activity in the praxis representation network (PRN), regardless of the used hand. Here we studied whether or not similar cerebral asymmetries are evident in non-righthanded individuals (adextrals). Sixty two participants, 28 righthanders and 34 non-righthanders (21 lefthanders, 13 mixedhanders), planned functional grasps of tools vs. grasps of control objects, and subsequently performed their pantomimed executions, in an event-related functional magnetic resonance imaging (fMRI) project. Both hands were tested, separately in two different sessions, counterbalanced across participants. After accounting for non-functional components of the prospective grasp, planning functional grasps of tools was associated with greater engagement of the same, left-hemisphere occipito-temporal, parietal and frontal areas of PRN, regardless of hand and handedness. Only when the analyses involved signal changes referenced to resting baseline intervals, differences between adextrals and dextrals emerged. Whereas in the left hemisphere the neural activity was equivalent in both groups (except for the occipito-temporo-parietal junction), its increases in the right occipito-temporal cortex, medial intraparietal sulcus (area MIP), the supramarginal gyrus (area PFt/PF), and middle frontal gyrus (area p9-46v) were significantly greater in adextrals. The inverse contrast was empty. Notably, when individuals with atypical and typical hemispheric phenotypes were directly compared, planning functional (vs. control) grasps invoked, instead, significant clusters located nearly exclusively in the left hemisphere of the typical phenotype. Previous studies interpret similar right-sided vs. left-sided increases in neural activity for skilled actions as handedness dependent, i.e., located in the hemisphere dominant for manual skills. Yet, none of the effects observed here can be purely handedness dependent because there were mixed-handed individuals among adextrals, and numerous mixed-handed and left-handed individuals possess the typical phenotype. Thus, our results clearly show that hand dominance has limited power in driving the cerebral organization of motor cognitive functions.

A table tennis serve versus rally hit elicits differential hemispheric electrocortical power fluctuations.

Human visuomotor control requires coordinated interhemispheric interactions to exploit the brain's functional lateralization. In right-handed individuals, the left hemisphere (right arm) is better for dynamic control and the right hemisphere (left arm) is better for impedance control. Table tennis is a game that requires precise movements of the paddle, whole body coordination, and cognitive engagement, providing an ecologically valid way to study visuomotor integration. The sport has many different types of strokes (e.g., serve, return, and rally shots), which should provide unique cortical dynamics given differences in the sensorimotor demands. The goal of this study was to determine the hemispheric specialization of table tennis serving - a sequential, self-paced, bimanual maneuver. We used time-frequency analysis, event-related potentials, and functional connectivity measures of source-localized electrocortical clusters and compared serves with other types of shots, which varied in the types of movement required, attentional focus, and other task demands. We found greater alpha (8-12 Hz) and beta (13-30 Hz) power in the right sensorimotor cortex than in the left sensorimotor cortex, and we found a greater magnitude of spectral power fluctuations in the right sensorimotor cortex for serve hits than return or rally hits, in all right-handed participants. Surprisingly, we did not find a difference in interhemispheric functional connectivity between a table tennis serve and return or rally hits, even though a serve could arguably be a more complex maneuver. Studying real-world brain dynamics of table tennis provides insight into bilateral sensorimotor integration.NEW & NOTEWORTHY We found different spectral power fluctuations in the left and right sensorimotor cortices during table tennis serves, returns, and rallies. Our findings contribute to the basic science understanding of hemispheric specialization in a real-world context.

Interdependency in lateralization of written word and face processing in right-handed individuals

It has been suggested that the right hemisphere lateralization typically observed for face processing may depend on lateralization of written word processing to the left hemisphere; a pattern referred to as the causal complementary principle of lateralization. According to a strong version of this principle, a correlation should be found between the degree of left and right hemisphere lateralization for word and face processing respectively. This has been observed in two studies, but only for left-handed individuals. The present study tested whether a similar lateralization pattern could be found in a relatively large sample of right-handed individuals (N = 210) using behavioral measures (divided visual field paradigms). It was also tested whether the degree of right hemisphere lateralization for face and global shape processing would correlate positively, as predicted by a strong version of the input asymmetry principle of lateralization. This was tested in a subsample (n = 189). Bayesian analyses found no evidence for lateralization interdependency as the observed data were 4–17 times more likely under the null hypothesis. Unfortunately, the reliabilities of the lateralization measures were found to be poor. While this dampens the firmness of the conclusions that can be drawn, it is argued that at present there is no positive evidence for strong interdependency between written word and face processing in right-handed individuals.

Identification of cognitive load-dependent activation patterns using working memory task-based fMRI at various levels of difficulty

Working memory, which is regarded as the foundation of cognitive processes, is a system that stores, processes, and manipulates information in short intervals of time that are actually needed for daily functioning. This study aimed to assess the brain activity of healthy controls (HC) while performing the N-back task, which is one of the most popularly used tests for evaluating working memory along with functional magnetic resonance imaging (fMRI). In this regard, we collected fMRI data from right-handed individuals in a 3.0 T scanner during the Persian version of the visual variant N-back task performance with three levels of complexity varied throughout the experiment (1, 2, and 3-back conditions) to increase the cognitive demands. The statistical parametric mapping (SPM12) software was used to analyze fMRI data for the identification of cognitive load-dependent activation patterns based on contrast images obtained from different levels of task difficulty. Our findings showed that as cognitive complexity increased, the number of significant activation clusters and cluster extent increased in several areas distributed in the cerebellum, frontoparietal lobes, insula, SMA, and lenticular nucleus, the majority of which are recognized for their role in working memory. Furthermore, deactivation patterns during 1-, 2-, and 3-back vs. 0-back contrasts revealed significant clusters in brain regions that are mostly described as being part of the default mode network (DMN). Based on previous research, our results supported the recognized involvement of the mentioned cortical and subcortical areas in various types or levels of N-back tasks. This study found that altering activation patterns by increasing task difficulty could aid in evaluating the various stages of cognitive dysfunction in many brain diseases such as multiple sclerosis (MS) and Alzheimer's disease by comparing controls in future studies to apply early appropriate treatment strategies.

Temporal Ordering and Auditory Resolution in Individuals with Sensorineural Hearing Loss.

Introduction Peripheral hearing loss, besides causing inadequate auditory input, can lead to distortions in the tonotopic auditory map and reorganization of neural networks. Therefore, the processing of temporal aspects of a sound stimulus and, consequently, the effectiveness of human communication can be negatively impacted. Objective To test the temporal ordering and auditory resolution of people with mild and moderate sensorineural hearing loss and to compare them with the those of people with normal hearing. Methods A total of 19 right-handed individuals aged 16 to 59 years with mild to moderate postlingually acquired symmetric bilateral sensorineural hearing loss participated in the study. They were submitted to frequency and duration pattern tests and a random gap detection test. Results The mean correct response rate in the frequency pattern test was of 66.3%, and, in the duration pattern test, 71.7%. The mean threshold in the random gap detection test was of 14.1 ms. A comparison with the criteria established for normal subjects without peripheral hearing loss revealed that more than half the subjects had abnormal results in the temporal ordering test, while a smaller fraction had reduced temporal resolution. Conclusions The performance of the subjects with acquired sensorineural hearing loss was poorer than that of the participants without peripheral hearing loss. Their results on the temporal ordering test were also poorer than in the temporal resolution test, demonstrating the importance of analyzing both these auditory skills in people with peripheral hearing loss.

The effect of handedness on upper extremity isometric strength symmetry

BackgroundUnderstanding upper extremity strength symmetry can have important implications for ergonomics assessment and design. Few studies have examined isometric joint strength symmetry of left-handed individuals, or examined how handedness can influence strength. As such, the purpose of this study was to investigate the influence of handedness on dominant/non-dominant (D/ND) strength ratio in several moment directions about the shoulder, elbow, wrist, and hand. It was hypothesized that the isometric strength symmetry of left-handed individuals would be significantly different from that of right-handed individuals. MethodsThe study recruited 28 participants to perform a series of maximal voluntary isometric contractions (MVCs) with both arms for various efforts about the shoulder, elbow, and wrist, as well as handgrip for a total of 68 MVCs. Strength symmetry ratios were computed, and a two-way mixed-model ANOVA evaluated the effects of handedness and MVC test on strength symmetry. InterpretationSignificant differences in D/ND ratios between right and left-handed individuals were found for 11 of the 17 explored exertion directions. Left-handed individuals tended to possess greater strength in their non-dominant limb, while right-handed individuals tended to have greater strength in their dominant limb. Left- and right-handed individuals often significantly differed in D/ND ratio, suggesting that separate normative values should be created to account for handedness when considering return-to-work or strength-based ergonomics design criterion.

Functional MRI Lateralization [M1] of dlPFC and Implications for Transcranial Magnetic Stimulation (TMS) Targeting.

The present study investigates a potential method of optimizing effective strategies for the functional lateralization of the dorsolateral prefrontal cortex (dlPFC) while in a scanner. Effective hemisphere lateralization of the dlPFC is crucial for lowering the functional risks connected to specific interventions (such as neurosurgery and transcranial magnetic stimulation (TMS), as well as increasing the effectiveness of a given intervention by figuring out the optimal location. This task combines elements of creative problem solving, executive decision making based on an internal rule set, and working memory. A retrospective analysis was performed on a total of 58 unique participants (34 males, 24 females, Mage = 42.93 years, SDage = 16.38). Of these participants, 47 were classified as right-handed, 7 were classified as left-handed, and 4 were classified as ambidextrous, according to the Edinburgh Handedness Inventory. The imaging data were qualitatively judged by two trained, blinded investigators (neurologist and neuropsychologist) for dominant handedness (primary motor cortex) and dominant dorsolateral prefrontal cortex (dlPFC). The results demonstrated that 21.4% of right-handed individuals showed a dominant dlPFC localized to the right hemisphere rather than the assumed left, and 16.7% of left-handers were dominant in their left hemisphere. The task completed in the scanner might be an efficient method for localizing a potential dlPFC target for the purpose of brain stimulation (e.g., TMS), though further study replications are needed to extend and validate these findings.

Hand Dominance Is Not of Significance in Performing Fundamental Arthroscopic Skills Simulation Training Tasks

To compare the performance of the dominant and nondominant hand during fundamental arthroscopic simulator training. Surgical trainees who participated in a 2-day simulator training course between 2021 and 2023 were classified, according to their arthroscopic experience in beginners and competents. Only right-handed individuals with complete data sets were included in the study. Ambidexterity was trained using a box trainer (Fundamentals of Arthroscopic Surgery Training, Virtamed AG, Schlieren, Switzerland).Two tasks, periscoping for learning camera guidance and triangulation for additional instrument handling, were performed 4 times with the camera in the dominant hand and then in the nondominant hand. For each task, exercise time, camera path length, and instrument path length were recorded and analyzed. Out of 94 participants 74 right-handed individuals (22 females, 52 males) were classified to novices (n= 43, less than 10 independently performed arthroscopies) and competents (n= 31, more than 10 independently performed arthroscopies). Competents performed significantly better than novices. No significant difference was found after changing the guiding hand for the camera from the dominant to the nondominant hand regarding the camera path length and the instrument path length. Notably, tasks were performed even faster when using the camera in the nondominant hand. Our data demonstrate that the learned manual skills during basic arthroscopic training are quickly transferred to the contralateral side. In consequence, additional fundamental skills training for camera guidance and instrument handling of the nondominant hand are not necessary. For skillful arthroscopy, camera guidance and instrument handing must be equally mastered with both hands. It is important to understand how hand dominance may affect learning during arthroscopic simulator training.

Modeling to explore and challenge inherent assumptions when cultural norms have changed: a case study on left-handedness and life expectancy

BackgroundIn 1991, Halpern and Coren claimed that left-handed people die nine years younger than right-handed people. Most subsequent studies did not find support for the difference in age of death or its magnitude, primarily because of the realization that there have been historical changes in reported rates of left-handedness.MethodsWe created a model that allowed us to determine whether the historical change in left-handedness explains the original finding of a nine-year difference in life expectancy. We calculated all deaths in the United States by birth year, gender, and handedness for 1989 (the Halpern and Coren study was based on data from that year) and contrasted those findings with the modeled age of death by reported and counterfactual estimated handedness for each birth year, 1900–1989.ResultsIn 1989, 2,019,512 individuals died, of which 6.4% were reportedly left-handed based on concurrent annual handedness reporting. However, it is widely believed that cultural pressures may have caused an underestimation of the true rate of left-handedness. Using a simulation that assumed no age of death difference between left-handed and right-handed individuals in this cohort and adjusting for the reported rates of left-handedness, we found that left-handed individuals were expected to die 9.3 years earlier than their right-handed counterparts due to changes in the rate of left-handedness over time. This difference of 9.3 years was not found to be statistically significant compared to the 8.97 years reported by Halpern and Coren. When we assumed no change in the rate of left-handedness over time, the survival advantage for right-handed individuals was reduced to 0.02 years, solely driven by not controlling for gender. When we considered the estimated age of death for each birth cohort, we found a mean difference of 0.43 years between left-handed and right-handed individuals, also driven by handedness difference by gender.ConclusionWe found that the changing rate of left-handedness reporting over the years entirely explains the originally reported observation of nine-year difference in life expectancy. In epidemiology, new information on past reporting biases could warrant re-exploration of initial findings. The simulation modeling approach that we use here might facilitate such analyses.

Comprehensive Normative Data for Objective Vestibular Tests.

Vestibular dysfunction is a debilitating disorder frequently encountered in neurological and otological settings. The vestibular system is a complex network between peripheral and central mechanisms. This innate complexity of the vestibular system necessitates objective test procedures for evidence-based diagnostic formulations and intervention. Objective tests aid in the evaluation of both peripheral and central vestibular pathologies. Establishing and availability of comprehensive normative data for these objective tests is crucial for clinicians and researchers alike. This is a prospective study involving 120 participants (both males and females) aged between 18 and 55 years. All participants were right-handed individuals and had no significant medical history. On pre-set protocols, cVEMP (cervical vestibular evoked myogenic potential), oVEMP (ocular vestibular evoked myogenic potential), vHIT (video head impulse test), and VNG (videonystagmography) were done. While all participants (n=120) underwent cVEMP, oVEMP, vHIT, saccade, smooth pursuit, and optokinetic tests, only 109 participants consented to the caloric test. Each test's mean, standard deviation, median, quartile, and third quartiles have been recorded. A right-left comparison yielded no significant difference on cVEMP, oVEMP, caloric test, smooth pursuit, and optokinetic test. However, few vHIT and saccade parameters did reveal significant differences. This study presents comprehensive normative data for cVEMP, oVEMP, vHIT, caloric test on VNG, and oculomotor tests (smooth pursuit, saccade, optokinetic) on VNG. The test results were in concordance with previously published data. The significant difference between the right and left sides in vHIT may be because of the monocular goggles used for the testing. This study brings out the normative data for various vestibular tests on individuals aged between 18-55 years. This information could aid both clinicians and researchers working in the field of vestibular science.

Influence of Handedness Preference on Visuospatial Ability in Lampung Province

The preference for using the right or left hand for different uni-manual tasks is known as handedness. Handedness as functional asymmetry has a correlation with the asymmetric brain. Most types of tools have been developed for right-handed use, leading to different adaptations between left-handed and right-handed individuals. Visuospatial, as one of the cognitive processes, is the ability to visualize two- and or three-dimensional objects. This function allows individuals to remember, plan for the future, navigate, and make decisions, thus visuospatial is one of the primary mental aspects in humans. The aim of this study was to assess whether being left-handed was associated with visuospatial ability. Respondents in this study were 148 adult individuals who lived in Lampung Province. Handedness was assessed based on a questionnaire of self-confessed and hand preference of 10 daily activities. Hand grip performance was measured by using a hand dynamometer. The ability of visuospatial was assessed by using the Right-Left Discrimination method. The results of the visuospatial ability test showed that left-handed individuals had a better average score of visuospatial than right-handed ones (44.00 &gt; 40.86). Males had better visuospatial ability than females (estimate = -0.0768; p-value: 0.0481). The influence of handedness on visuospatial ability was discussed

The Effects of Hand Preference on Measures of Psychological Well-Being in a Sample of Older Adults in the Kingdom of Saudi Arabia.

Generally, being left-handed has been linked to poorer mental health and quality of life. However, given that few studies have investigated these links in Saudi Arabia and that the prevalence of mental illness in the general population is rising, it is important to explore whether left-handedness can be considered a risk factor in a sizable, general population. To investigate whether left-handers experience psychological well-being or good quality of life. A cross-sectional study among adults in Saudi Arabia was conducted from March 6, 2022to February 27, 2023. The study included (N = 2862) respondents who met the inclusion criteria, with an average age of 28.95 years. Left-handed individuals made up 31.7%, whereas right-handed individuals made up 60.3%, and ambidextrous individuals made up 7.9% of the population. Using the Mental Health Quality of Life questionnaire (MHQoL-7D) scoring manual, the quality of life for both left-and right-handers was evaluated. Those who were right-handed had a higher quality of life than those who were left-handed. Multivariate Analysis of Variance (MANOVA) was conducted, and the findings showed that neither the left-handed nor the right-handed group significantly differed in their levels of poor quality of life or psychological well-being. Using the left or the right hand had no effect on one's quality of life or degree of well-being. Further studies with a larger sample size are needed to examine this result in more detail.

THE EFFECTS OF NEUROTICISM ON APPROACH-AVOIDANCE-RELATED MOTOR BEHAVIOR

In the present study, we aimed to investigate whether positive emotional stimuli may affect high and low neuroticism individuals’ maximal voluntary contraction (MVC) level of the biceps brachii muscle, which is considered a motor representation of approach behavior. The sample consisted of 36 right-handed individuals (12 females) ranging in age from 18 to 27 (M= 23.516 [2.120]). Participants completed items from the Big Five Factor Personality Inventory concerning Neuroticism. After completing the psychometric test, we exposed participants to the high valance low arousal pictures selected from the International Affective Picture System (IAPS) via Biotrace+ software during the execution of arm flexions. Participants made 2 MVC attempts for each experimental condition lasting 6 seconds and rested 3 minutes between MVC attempts to eliminate the effect of fatigue. Results of Pearson correlation analysis revealed that the percent change of MVC was positively associated with neuroticism (r= .368, p&lt; .05). The results also showed that the percent change of MVC of the high neuroticism group was significantly greater than the percent change of the low neuroticism group [t(36)= -2.449, p= .020]. Results provided some support for our hypothesis. Hence the data demonstrated that positive emotional stimuli decreased the MVC of the biceps brachii muscle in individuals with low neuroticism. On the contrary, MVC levels of high neuroticism individuals remained almost stable in response to positive emotional stimuli.

Deciphering Functional Connectivity Differences Between Motor Imagery and Execution of Target-Oriented Grasping.

This study aimed to delineate overlapping and distinctive functional connectivity in visual motor imagery, kinesthetic motor imagery, and motor execution of target-oriented grasping action of the right hand. Functional magnetic resonance imaging data were obtained from 18 right-handed healthy individuals during each condition. Seed-based connectivity and multi-voxel pattern analyses were employed after selecting seed regions with the left primary motor cortex and supplementary motor area. There was equivalent seed-based connectivity during the three conditions in the bilateral frontoparietal and temporal areas. When the seed region was the left primary motor cortex, increased connectivity was observed in the left cuneus and superior frontal area during visual and kinesthetic motor imageries, respectively, compared with that during motor execution. Multi-voxel pattern analyses revealed that each condition was differentiated by spatially distributed connectivity patterns of the left primary motor cortex within the right cerebellum VI, cerebellum crus II, and left lingual area. When the seed region was the left supplementary motor area, the connectivity patterns within the right putamen, thalamus, cerebellar areas IV-V, and left superior parietal lobule were significantly classified above chance level across the three conditions. The present findings improve our understanding of the spatial representation of functional connectivity and its specific patterns among motor imagery and motor execution. The strength and fine-grained connectivity patterns of the brain areas can discriminate between motor imagery and motor execution.

The Human Centromedial Amygdala Contributes to Negative Prediction Error Signaling during Appetitive and Aversive Pavlovian Gustatory Learning.

Prediction error (PE) is the mismatch between a prior expectation and reality, and it lies at the core of associative learning about aversive and appetitive stimuli. Human studies on fear learning have linked the amygdala to aversive PEs. In contrast, the relationship between the amygdala and PE in appetitive settings and stimuli, unlike those that induce fear, has received less research attention. Animal studies show that the amygdala is a functionally heterogeneous structure. Nevertheless, the role of the amygdala nuclei in PE signaling remains unknown in humans. To clarify the role of two subdivisions of the human amygdala, the centromedial amygdala (CMA) and basolateral amygdala (BLA), in appetitive and aversive PE signaling, we used gustatory pavlovian learning involving eating-related naturalistic outcomes. Thirty-eight right-handed individuals (19 females) participated in the study. We found that surprise with neutral feedback when a reward is expected triggers activity within the left and right CMA. When an aversive outcome is expected, surprise with neutral feedback triggers activity only within the left CMA. Notably, the BLA was not activated by those conditions. Thus, the CMA engages in negative PE signaling during appetitive and aversive gustatory pavlovian learning, whereas the BLA is not critical for this process. In addition, PE-related activity within the left CMA during aversive learning is negatively correlated with neuroticism and positively correlated with extraversion. The findings indicate the importance of the CMA in gustatory learning when the value of outcomes changes and have implications for understanding psychological conditions that manifest perturbed processing of negative PEs.SIGNIFICANCE STATEMENT A discrepancy between a prediction and an actual outcome (PE) plays a crucial role in learning. Learning improves when an outcome is more significant than expected (positive PE) and worsens when it is smaller than expected (negative PE). We found that the negative PE during appetitive and aversive taste learning is associated with increased activity of the CMA, which suggests that the CMA controls taste learning. Our findings may have implications for understanding psychological states associated with deficient learning from negative PEs, such as obesity and addictive behaviors.

Gender-specific anatomical correlations of schizotypy in healthy individuals

IntroductionSchizotypy refers to a continuum of symptoms from subclinical manifestations in the general population to severe symptoms in schizophrenia spectrum disorders. Neuroimaging studies revealed significant relationships between schizotypy and cortical anatomy in the general population. However, it remains unclear whether these structural associations has a gender specificity.ObjectivesThe present study used structural MRI data to investigate the relationship between subclinical schizotypy symptoms and cortical and subcortical morphometric measures in male and female samples of healthy individuals.Methods164 right-handed healthy unmedicated individuals (18.0-34.9 years, 57% females) underwent structural MRI at 3T Philips scanner. T1-weighted images were processed via FreeSurfer 6.0 to quantify cortical thickness for 34 regions-of-interest (ROIs) according to Desikan atlas and volumes for 7 subcortical structures at each hemisphere. Schizotypy levels were assessed using self-report Schizotypal Personality Questionnaire, total schizotypy score and 4 factors scores (Cognitive-perceptual, negative, disorganized and paranoid factors as per Stefanis et al. Schizophr Bull. 2004; 30 335-350) were calculated. Partial correlation analysis (ppcor version 1.1, R version 4.2.1) was used to assess the associations between ROIs cortical thickness and total schizotypy or 4 factors scores including age and sex as covariates. The same analysis was performed for subcortical volumes including intracranial volume as additional covariate.ResultsIn male group we revealed a positive correlation between greater thickness of the left caudal middle frontal gyrus and higher total schizotypy (r=0.42, punc=0.0003, 95% CI [0.21–0.60]) and negative factor of schizotypy (r=0.49, punc&lt;0.0001, 95% CI [0.28–0.65]) (Image). No correlations survived correction for multiple comparisons in female sample. There were no differences in age, caudal middle frontal gyrus thickness, total schizotypy or negative factor of schizotypy scores between male and female subgroups.Image:ConclusionsThe results suggest that the association of dorsolateral prefrontal cortex (DLPFC) and levels of schizotypy is gender specific. We showed that total and negative schizotypy positively correlated with thicker DLPFC in male but not in female sample. The present data are inverse to findings of prefrontal cortical thinning observed in schizophrenia. Such correlations suggest that thicker cortex could be a potential compensatory mechanism or could reflect alterations in trajectory of cortical thickness reductions across the lifespan.The work was supported by RFBR grant 20-013-00748Disclosure of InterestNone Declared