Visuomotor Integration Research Articles

QOL-19. PARENT-REPORTED COGNITIVE PROBLEMS AND DIRECT ASSESSMENT OF COGNITION IN CHILDREN TREATED FOR A BRAIN TUMOR

The Pediatric Perceived Cognitive Function (PedsPCF) item bank is a short parent and self-reported cognitive screening questionnaire developed in the context of pediatric oncology. The PedsPCF demonstrated satisfactory psychometric properties and the scores of the PedsPCF are found to be associated with clinical outcomes. Today little research is available to evaluate whether the PedsPCF is correlated with direct assessments of neurocognitive domains. The aim of the current study is to investigate whether important cognitive domains, such as different aspects of intelligence, memory, visuomotor integration can predict the PedsPCF score. We obtained 100 PedsPCF filled in by parents from children treated for a brain tumor. All these children completed a comprehensive neuropsychological battery. Mean age at diagnosis was 7.47 years and mean age at completion of PedsPCF and testing 13.84. The most common diagnoses were pilocytic astrocytoma (n=43) and medulloblastoma (n=14). A linear regression model with verbal comprehension, perceptual reasoning, processing speed, visuomotor integration as predictors for overall PedsPCF score was significant (p.005), but the overall model fit was limited (adjusted R2: 14%). Visuomotor integration and processing speed were significant predictors (beta = 0.56 and -0.29). Our results are in line with the overall finding that the correlation between questionnaires assessing quality of survival and direct assessments of cognition are low. For clinical practice these results are important as the PedsPCF can’t be used to replace direct cognitive assessments or vice versa.

Location and Size of Preterm Cerebellar Hemorrhage and Childhood Development

To examine the association between cerebellar hemorrhage (CBH) size and location and preschool-age neurodevelopment in very preterm neonates. Preterm magnetic resonance images of 221 very preterm neonates (median gestational age = 27.9 weeks) were manually segmented for CBH quantification and location. Neurodevelopmental assessments at chronological age 4.5 years included motor (Movement Assessment Battery for Children, 2nd Edition [MABC-2]), visuomotor integration (Beery-Buktenica Developmental Test of Visual-Motor Integration, 6th Edition), cognitive (Wechsler Primary and Preschool Scale of Intelligence, 3rd Edition), and behavioral (Child Behavior Checklist) outcomes. Multivariable linear regression models examined the association between CBH size and 4.5-year outcomes accounting for sex, gestational age, and supratentorial injury. Probabilistic maps assessed CBH location and likelihood of a lesion to predict adverse outcome. Thirty-six neonates had CBH: 14 (6%) with only punctate CBH and 22 (10%) with ≥1 larger CBH. CBH occurred mostly in the inferior aspect of the posterior lobes. CBH total volume was independently associated with MABC-2 motor scores at 4.5 years (β = -0.095, 95% confidence interval = -0.184 to -0.005), with a standardized β coefficient (-0.16) that was similar to that of white matter injury volume (standardized β = -0.22). CBH size was similarly associated with visuomotor integration and externalizing behavior but not cognition. Voxelwise odds ratio and lesion-symptom maps demonstrated that CBH extending more deeply into the cerebellum predicted adverse motor, visuomotor, and behavioral outcomes. CBH size and location on preterm magnetic resonance imaging were associated with reduced preschool motor and visuomotor function and more externalizing behavior independent of supratentorial brain injury in a dose-dependent fashion. The volumetric quantification and localization of CBH, even when punctate, may allow opportunity to improve motor and behavioral outcomes by providing targeted intervention. ANN NEUROL 2020;88:1095-1108.

Identification of a distinct association fiber tract \u201cIPS-FG\u201d to connect the intraparietal sulcus areas and fusiform gyrus by white matter dissection and tractography

The intraparietal sulcus (IPS) in the posterior parietal cortex (PPC) is well-known as an interface for sensorimotor integration in visually guided actions. However, our understanding of the human neural network between the IPS and the cortical visual areas has been devoid of anatomical specificity. We here identified a distinctive association fiber tract “IPS-FG” to connect the IPS areas and the fusiform gyrus (FG), a high-level visual region, by white matter dissection and tractography. The major fiber bundles of this tract appeared to arise from the medial bank of IPS, in the superior parietal lobule (SPL), and project to the FG on the ventral temporal cortex (VTC) in post-mortem brains. This tract courses vertically at the temporo-parieto-occipital (TPO) junction where several fiber tracts intersect to connect the dorsal-to-ventral cortical regions, including the vertical occipital fasciculus (VOF). We then analyzed the structural connectivity of this tract with diffusion-MRI (magnetic resonance imaging) tractography. The quantitative tractography analysis revealed the major streamlines of IPS-FG interconnect the posterior IPS areas (e.g., IP1, IPS1) with FG (e.g., TF, FFC, VVC, PHA2, PIT) on the Human Connectome Project multimodal parcellation atlas (HCP MMP 1.0). Since the fronto-parietal network, including the posterior IPS areas, is recruited by multiple cognitive demands, the IPS-FG could play a role in the visuomotor integration as well as the top-down modulation of various cognitive functions reciprocally.

Altered visuomotor integration in complex regional pain syndrome

During self-guided movements, we optimise performance by combining sensory and self-motion cues optimally, based on their reliability. Discrepancies between such cues and problems in combining them are suggested to underlie some pain conditions. Therefore, we examined whether visuomotor integration is altered in twenty-two participants with upper or lower limb complex regional pain syndrome (CRPS) compared to twenty-four controls. Participants located targets that appeared in the unaffected (CRPS) / dominant (controls) or affected (CRPS) / non-dominant (controls) side of space, using the hand of their unaffected/dominant or affected/non-dominant side of the body. For each side of space and each hand, participants located the target using visual information and no movement (vision only condition), an unseen pointing movement (self-motion only condition), or a visually-guided pointing movement (visuomotor condition). In all four space-by-hand conditions, controls reduced their variability in the visuomotor compared to the vision and self-motion only conditions and in line with a model prediction for optimal integration. Participants with CRPS showed similar evidence of cue combination in two of the four conditions. However, they had better-than-optimal integration for the unaffected hand in the affected space. Furthermore, they did not integrate optimally for the hand of the affected side of the body in unaffected space, but instead relied on the visual information. Our results suggest that people with CRPS can optimally integrate visual and self-motion cues under some conditions, despite lower reliability of self-motion cues, and use different strategies to controls.

Children with Autism Spectrum Disorder Show Impairments During Dynamic Versus Static Grip-force Tracking.

Impairments in visuomotor integration (VMI) may contribute to anomalous development of motor, as well as social-communicative, skills in children with autism spectrum disorder (ASD). However, it is relatively unknown whether VMI impairments are specific to children with ASD versus children with other neurodevelopmental disorders. As such, this study addressed the hypothesis that children with ASD, but not those in other clinical control groups, would show greater deficits in high-VMI dynamic grip-force tracking versus low-VMI static presentation. Seventy-nine children, aged 7-17 years, participated: 22 children with ASD, 17 children with fetal alcohol spectrum disorder (FASD), 18 children with Attention-Deficit Hyperactivity Disorder (ADHD), and 22 typically developing (TD) children. Two grip-force tracking conditions were examined: (1) a low-VMI condition (static visual target) and (2) a high-VMI condition (dynamic visual target). Low-frequency force oscillations <0.5 Hz during the visuomotor task were also examined. Two-way ANCOVAs were used to examine group x VMI and group x frequency effects (α = 0.05). Children with ASD showed a difficulty, above that seen in the ADHD/FASD groups, tracking dynamic, but not static, visual stimuli as compared to TD children. Low-frequency force oscillations <0.25 Hz were also significantly greater in the ASD versus the TD group. This study is the first to report VMI deficits during dynamic versus static grip-force tracking and increased proportion of force oscillations <0.25 Hz during visuomotor tracking in the ASD versus TD group. Dynamic VMI impairments may be a core psychophysiologic feature that could contribute to impaired development of motor and social-communicative skills in ASD. LAY SUMMARY: Children with autism spectrum disorder (ASD) show difficulties using dynamic visual stimuli to guide their own movements compared to their typically developing (TD) peers. It is unknown whether children without a diagnosis of ASD, but with other neurological disorders, show similar difficulties processing dynamic visual stimuli. In this study, we showed that children with ASD show a difficulty using dynamic, but not static, visual stimuli to guide movement that may explain atypical development of motor and social skills.

Effects of longstanding degraded auditory signal on visuospatial, visuomotor, and visual attention skills in adults with hearing loss

Objective This study examined the consequences of long-term auditory deprivation on visuospatial functions, visuomotor functions, and visual attention skills in adults with early-onset hearing loss. Methods Fifteen adults with bilateral, early-onset (before age 3), severe-to-profound hearing loss who used spoken language participated in this study. Visuospatial (figure ground, form constancy, visual perception) and visuomotor functions (visuomotor integration, visual search) were examined using norm-referenced tests. Visual attention scales were examined using a computerized program, IVA plus continuous performance test. Results As a group, participants performed in the average range on visuospatial and visuomotor functions when compared to normative data presented in the test instruments. However, participants demonstrated below average performance on sustained visual attention. Duration of cochlear implant use positively correlated with one of the visual attention scales, namely visual speed. Conclusions The findings of the current study suggest that adults with early-onset hearing loss may demonstrate difficulties in sustaining attention to visual information. Data also suggest that increased experience with cochlear implant may ameliorate deficits associated with visual attention. Future studies should explore challenges experienced by adults with early-onset hearing loss in their daily activities that may result from this deficit and intervention programs that may enhance visual attention skills.

Sense of external agency is sustained by multisensory functional integration in the somatosensory cortex.

“Sense of agency” (SoA), the feeling of control for events caused by one's own actions, is deceived by visuomotor incongruence. Sensorimotor networks are implicated in SoA, however little evidence exists on brain functionality during agency processing. Concurrently, it has been suggested that the brain's intrinsic resting‐state (rs) activity has a preliminary influence on processing of agency cues. Here, we investigated the relation between performance in an agency attribution task and functional interactions among brain regions as derived by network analysis of rs functional magnetic resonance imaging. The action‐effect delay was adaptively increased (range 90–1,620 ms) and behavioral measures correlated to indices of cognitive processes and appraised self‐concepts. They were then regressed on local metrics of rs brain functional connectivity as to isolate the core areas enabling self‐agency. Across subjects, the time window for self‐agency was 90–625 ms, while the action‐effect integration was impacted by self‐evaluated personality traits. Neurally, the brain intrinsic organization sustaining consistency in self‐agency attribution was characterized by high connectiveness in the secondary visual cortex, and regional segregation in the primary somatosensory area. Decreased connectiveness in the secondary visual area, regional segregation in the superior parietal lobule, and information control within a primary visual cortex‐frontal eye fields network sustained self‐agency over long‐delayed effects. We thus demonstrate that self‐agency is grounded on the intrinsic mode of brain function designed to organize information for visuomotor integration. Our observation is relevant for current models of psychopathology in clinical conditions in which both rs activity and sense of agency are altered.

Evaluation of neuropsychological development of children diagnosed with primary monosymptomatic nocturnal enuresis: A pilot study.

Studies on primary monosymptomatic nocturnal enuresis have supported neuromotor development delay. This study aims to examine the neuropsychological development of children with primary monosymptomatic nocturnal enuresis. This study included 30 children diagnosed with primary monosymptomatic nocturnal enuresis and 30 healthy children. Both groups were analyzed by pediatric psychologists using the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Bender Gestalt Visual Motor Detection test. The WISC-R test is an intelligence test that includes six verbal subscales (information, similarities, arithmetic, vocabulary, judgment, and digit span) and six performance subscales (picture completion, picture arrangement, block design, object assembly, coding, and labyrinths). The Bender Gestalt test is a psychological assessment instrument used to evaluate visuomotor functioning, visuospatial functions, spatial memory, visuomotor integration skills, and visual perception skills. There were no differences in age (7.66±0.9 versus 8±1.07 years, p>0.05) or sex (20 females versus 20 males, p>0.05) between the groups. Picture completion (p=0.024), picture arrangement (p=0.001), and object assembly test (p=0.000) performance was found to be worse in subjects with primary monosymptomatic nocturnal enuresis. Similarity (p=0.021) and judgment tests (p=0.048) of the verbal subtests were also found to be delayed in the nocturnal enuresis cases. Our results suggest that children with nocturnal enuresis have lower performance compared with the control group in terms of abstract thinking, correct expression of thought, cause-result relation, short-term memory, and problem-solving ability. These children should be routinely tested by neurodevelopment tests and receive support in areas in which they are delayed.

Cerebellar – Premotor cortex interactions underlying visuomotor adaptation

Visuomotor adaptation (VMA) is a form of motor learning essential for performing day to day routines. Theoretical models and empirical evidence suggest a specific cortico-striato-cerebellar loop that mediates early and late learning in VMA. Here, we investigated dynamic changes in neural activity and connectivity when learning a novel visuomotor rotation using fMRI. We found that motor cortical regions, parietal cortex and cerebellum are recruited in the early phase of VMA, gradually reduce their activity as learning reaches plateau and rebound when the visuomotor rotation is removed. At this phase, dubbed de-adaptation, individual performance correlated with activity in motor and parietal cortex such that stronger activity was associated with better performance. Theory suggests that VMA is governed by the cortico-striato-cerebellar network during the early phase of learning and by the cortico-cerebellar loop at later stages. We tested this hypothesis using dynamic causal modelling and found distinct modulation of a cerebellar to dorsal premotor cortex (dPMC) loop. Specifically, the cerebellar to dPMC connection was modulated during adaptation, suggesting a release of inhibition and net excitatory effect of cerebellum on dPMC. The modulation of cerebellar to dPMC connection during de-adaptation was specifically related to behavioral learning parameter: stronger release of inhibition of the cerebellar to dPMC connection was associated with better de-adaptation. We interpret these findings to reflect dynamic interactions between representation of movement in cerebellum and visuomotor integration in dPMC.

Proposed Phenotype for Females with a SETD5 Gene Variation: A Case Report

Background: SET domain containing 5 (SETD5) gene variants have been linked to developmental delays, craniofacial abnormalities, and intellectual disability (ID). Prior research examining the phenotypic presentation of individuals with SETD5 variations has been based largely on a male-dominated cohort and case studies. Evidence of a possible protective effect in females prompts the need for additional research on the neuropsychological presentation of females with a SETD5 variation. The current study aims to initiate this effort by discussing the neurocognitive profile of a right-handed 7-year-old Caucasian female with a diagnosed SETD5 variation. Methods and findings: The patient was referred for neuropsychological evaluation due to reported reading, writing, and fine motor difficulties. She presented with distinct dysmorphic features: head circumference <1st percentile, syndactyly of toes, clinodactyly of fifth fingers, and a long smooth philtrum with thin upper lip. Interpersonally, the patient was highly social. Cognitive testing revealed low average intelligence, with intact verbal/language functioning and impaired nonverbal/fluid reasoning abilities. Deficits were also observed in fine motor dexterity, visuomotor integration, attention, and broad academic achievement. The patient was ultimately referred for genetic testing, which revealed a de novo SETD5 frame shift variant resulting in a truncation of the gene copy near the end of the gene. Conclusion: This case study provides evidence for phenotypic differences between males and females with SETD5 gene variations. While males exhibit ID, females may present with significant deficits in nonverbal reasoning skills. Females may also display more fully developed social skills and a lack of repetitive stereotyped behaviors. Further research is warranted to clarify the unique presentation among females with SETD5 variations to better inform diagnosis and treatment planning.

Visuomotor Integration for Coupled Hand Movements in Healthy Subjects and Patients With Stroke.

Many studies have investigated the bilateral upper limb coordination during movements under different motor and visual conditions. Bilateral training has also been proposed as an effective rehabilitative protocol for patients with stroke. However, the factors influencing in-phase vs. anti-phase coupling have not yet been fully explored. In this study, we used a motion capture device based on two infrared distance sensors to assess whether the up and down oscillation of the less functional hand (the non-dominant one in healthy younger and older subjects and the paretic one in patients with stroke) could be influenced by in-phase or anti-phase coupling of the more functional hand and by visual feedback. Similar patterns were found between single hand movements and in-phase coupled movements, whereas anti-phase coupled movements were less ample, less sinusoidal, but more frequent. These features were particularly evident for patients with stroke who showed a reduced waveform similarity of bilateral movements in all conditions but especially for anti-phase movements under visual control. These results indicate that visuomotor integration in patients with stroke could be less effective than in healthy subjects, probably because of the attentional overload required when moving the two limbs in an alternating fashion.

Sensorimotor skills in autism spectrum disorder: A meta-analysis

BackgroundSensorimotor skills are often reported as atypical in individuals with autism spectrum disorder (ASD). Little is known about how sensorimotor skills in ASD may vary across development and with symptom severity. The main objective of this study was to conduct a comprehensive quantitative meta-analysis of sensorimotor skills in ASD. The specific aims were: to assess impairment of gross and fine sensorimotor skills in ASD, to examine the effect of age on sensorimotor skills in ASD and to examine the relationship between sensorimotor skills and ASD symptom severity. MethodAn exhaustive search was conducted in Psycnet, PubMed, Web of Science and Cochrane Database to identify studies in ASD from 1980 to 2018 that involved quantitative evaluations of motor coordination, motor impairments, arm movement, gait, postural stability, visuomotor or auditory motor integration. A total of 139 studies were included and this represent 3436 individuals with ASD. ResultsResults strongly support the presence of deficits in overall sensorimotor abilities in ASD (Hedges’ g = 1.22, p < 0.001) and these atypicalities extended to fine and gross sensorimotor abilities. Sensorimotor abilities increased with age, but did not appear to covary with symptom severity. ConclusionsThese results highlight the importance to target these deficits in future interventions and consider the impact of sensorimotor impairments across research, therapy, and educational settings.

Cortical visuomotor interactions in Freezing of Gait: A TMS approach

Altered cortical visuomotor integration has been involved in the pathophysiology of freezing of gait (FoG) in parkinsonism. The aim of this study was to assess the connections between the primary visual (V1) and motor (M1) areas with a paired-pulse, twin-coil transcranial magnetic stimulation (TMS) technique in patients with FoG. Twelve Parkinson's disease (PD) patients suffering from levodopa-responsive-FoG (off-FoG) were compared with 12 PD patients without FoG and 12 healthy subjects of similar age/sex. In the "off" condition, visuomotor connections (VMCs) were assessed bilaterally. A conditioning stimulus over the V1 phosphene hotspot was followed at interstimulus intervals (ISIs) of 18 and 40ms by a test stimulus over M1, to elicit motor evoked potentials (MEPs) in the contralateral first dorsal interosseous muscle. Significant (P<0.01), bilateral effects due to VMCs were detected in all three groups, consisting of a MEP suppression at ISI 18 and 40ms. However, in PD patients with FoG, the MEP suppression was significantly (P<0.05) enhanced, both at ISI 18-40ms, in comparison with the other two groups. The phenomenon was limited to the right hemisphere. PD patients with FoG showed an excessive inhibitory response of the right M1 to inputs travelling from V1 at given ISIs. Right-sided alterations of the cortical visuomotor integration may contribute to the pathophysiology of FoG.

Role of Physiotherapy Intervention in Rare Case of Moya Moya Syndrome - A Single Case Study

Introduction: Moya moya syndrome is a moya moya angiopathy related secondarily to any neurological symptom or because of a specific acquired or inherited origin presenting with sensory and motor impairments. Although the disease is quite common in Japan, many cases have been reported around the globe, including North America, Europe, and India. Epidemiologic studies in Japan have estimated the annual incidence of moya moya disease to be 0.35 to 0.94 per 100000 people. This case studies the role of physiotherapy as it is not explored much in the paediatric population. Material and Methodology: A child who was diagnosed with moya moya syndrome presented to us at the age of 3.3 years and was evaluated on GMFM-88 scale, Visuo-Motor Integration (VMI) component of PDMS-2 scale along with Manual Ability Classification System (MACS). Physiotherapy intervention was done based on impairments to improve motor function. Results: GMFM-88 was administered for 4 times in 18 months. A total score of 38 was observed at first administration and a total of 24 score was observed at 18th month of administration. The VMI score of PDMS-2 scale did not change pre and post intervention. Conclusion: This single case study shows about the nature of the syndrome and individualized integrated protocol which is needed for the evaluation and tretment in the cases of moya moya syndrome population which needs to be segregated from cerebral palsy.

Central neurogenetic signatures of the visuomotor integration system

Visuomotor impairments characterize numerous neurological disorders and neurogenetic syndromes, such as autism spectrum disorder (ASD) and Dravet, Fragile X, Prader-Willi, Turner, and Williams syndromes. Despite recent advances in systems neuroscience, the biological basis underlying visuomotor functional impairments associated with these clinical conditions is poorly understood. In this study, we used neuroimaging connectomic approaches to map the visuomotor integration (VMI) system in the human brain and investigated the topology approximation of the VMI network to the Allen Human Brain Atlas, a whole-brain transcriptome-wide atlas of cortical genetic expression. We found the genetic expression of four genes-TBR1, SCN1A, MAGEL2, and CACNB4-to be prominently associated with visuomotor integrators in the human cortex. TBR1 gene transcripts, an ASD gene whose expression is related to neural development of the cortex and the hippocampus, showed a central spatial allocation within the VMI system. Our findings delineate gene expression traits underlying the VMI system in the human cortex, where specific genes, such as TBR1, are likely to play a central role in its neuronal organization, as well as on specific phenotypes of neurogenetic syndromes.

The role of the striatum in visuomotor integration during handwriting: an fMRI study.

This study investigates the role of the dorsal/sensorimotor striatum in visuomotor integration (i.e., the transformation of internal visual information about letter shapes into motor output) during handwriting. Twenty healthy participants underwent fMRI scanning with tasks consisting of self-paced handwriting of alphabetically ordered single letters and simple dots, with both tasks performed without visual feedback. Functional connectivity (FC) from these two tasks was compared to demonstrate the difference between coordinated activity arising during handwriting and the activity during a simpler motor condition. Our study focused upon the writing-specific cortico-striatal network of preselected regions of interest consisting of the visual word form area (VWFA), anterior intraparietal sulcus/superior parietal lobule, striatum, premotor cortex/Exner's area, and primary and supplementary motor regions. We observed systematically increased task-induced cortico-striatal and cortico-cortical FC. This increased synchronization of neural activity between the VWFA, i.e., the visual cortical area containing information about letter shapes, and the frontoparietal motor regions is mediated by the striatum. These findings suggest the involvement of the striatum in integrating stored letter-shape information with motor planning and execution during handwriting.

Circuit mechanisms of spatial perception and visuomotor integration

Animals can make appropriate decisions based on sensory information about the environment. Vision is one of the most critical ability for survival in dynamic situations in nature, particularly for mammalian species, such as primates, carnivores, and rodents. Although there is a huge computational cost involved in processing visual information, the brain can perform this task very rapidly using well-organized parallel and hierarchical neural circuits, enabling animals to rapidly sense the environment and, in turn, perform adaptive actions. Physiological, psychophysical, and clinical studies over hundreds of years have delineated the neural circuit mechanisms of the visual system. Artificial intelligence and robotics have also started making progress in this area. However, due to technical limitations, there are still many open questions that elude explanation in understanding the neural mechanism of visuomotor integration. Herein, we initially describe the anatomical structures of occipital cortices related to vision and then provide an overview of the physiological and clinical studies of the dorsal visual pathway related to spatial perception and prediction in non-human primate species. Finally, we introduce recent approaches in which rodents have been used as model species to elucidate the neural circuit mechanism of visually-guided behavior. Uncovering neural implementation of the association between visual-spatial perception and visuomotor function could provide key insights into the engineering of highly active robots and could also contribute to the development of novel therapeutic strategies addressing visual impairment and psychiatric/neurological disorders.

Brain structure changes in nondemented seniors after six-month dance-exercise intervention.

To evaluate effects of a six-month intensive dance-exercise intervention (DI) on cognition and brain structure in a mixed group of healthy seniors and people with mild cognitive impairment. Subjects (aged˃60years with no dementia or depression) were randomly assigned to either a DI group or a life as usual (LAU) group. Detailed neuropsychological testing, measures of physical fitness and brain MRI encompassing T1 structural and diffusion tensor imaging (DTI) were performed at baseline and after 6months. We assessed changes in cortical thickness and DTI parameters derived from tract-based spatial statistics. Altogether 62 individuals (n=31 in the DI group) completed the protocol. The groups were matched for their demographic and clinical variables. After 6months, we found significant cortical thickening in the right inferior temporal, fusiform and lateral occipital regions in the dancers compared to controls. Significant increases of radial and mean diffusivity were observed in various white matter tracts in the dancers; however, no differences were observed between the DI and LAU groups. The DI group as compared to the LAU group showed subtle improvements in executive functions. We observed DI-induced improvement in executive functions and increases of cortical thickness in the lateral occipitotemporal cortex which is engaged in action observation, visuomotor integration and action imitation, that is activities that are all important for motor learning and executing skilled movements.

Inhibitory Theta Burst Stimulation Highlights the Role of Left aIPS and Right TPJ during Complementary and Imitative Human-Avatar Interactions in Cooperative and Competitive Scenarios.

Competitive and cooperative interactions are based on anticipation or synchronization with the partner's actions. Both forms of interaction may either require performing imitative or complementary movements with respect to those performed by our partner. We explored how parietal regions involved in the control of imitative behavior (temporo-parietal junction, TPJ), goal coding and visuo-motor integration (anterior intraparietal sulcus, aIPS) contribute to the execution of imitative and complementary movements during cooperative and competitive interactions. To this aim, we delivered off-line non-invasive inhibitory brain stimulation to healthy individuals' left aIPS and right TPJ before they were asked to reach and grasp an object together with a virtual partner by either performing imitative or complementary interactions. In different blocks, participants were asked to compete or cooperate with the virtual partner that varied its behavior according to cooperative or competitive contexts. Left aIPS and right TPJ inhibition impaired individuals' performance (i.e., synchrony in cooperative task and anticipation in competition) during complementary and imitative interactions, respectively, in both cooperative and competitive contexts, indicating that aIPS and TPJ inhibition affects own-other action integration and action imitation (that are different in complementary vs imitative interactions) more than action synchronization or anticipation (that are different in cooperative vs competitive contexts).

White matter correlates of gait perturbations resulting from spontaneous and lateralized attention in healthy older adults: A dual-task study.

To date the neural mechanisms behind gait perturbations caused by dual-task paradigms are still unknown. Therefore, the present study examined white matter correlates of gait perturbations caused by a dichotic listening task where spontaneous (free focus of attention) and lateralized attentional control (voluntary attention directed to right or left-ear) were tested. Fifty-nine right-handed, healthy older adults (59-88 years) were evaluated during single-task walking and three dual-task conditions. Dual-task costs were calculated for mean (DTCM) and coefficients of variation (DTCCoV) in gait speed, step length, stride length and step width. Volume, fractional anisotropy and mean diffusivity were estimated using global probabilistic tractography for the 18 major brain tracts and correlated with the DTCs. Data demonstrated that DTCs on gait speed and step length significantly correlated with white matter integrity and volume in various tracts. Perturbations on gait speed caused by spontaneous attention were related to frontal circuitry integrity including corpus callosum, while perturbations on gait speed and step length produced by voluntary lateralized attention were associated to tracts subserving visuomotor integration and frontal function.