Visuomotor Integration Research Articles

Interaction between visual and motor cortex: a transcranial magnetic stimulation study.

The major link between the visual and motor systems is via the dorsal stream pathways from visual to parietal and frontal areas of the cortex. Although the pathway appears to be indirect, there is evidence that visual input can reach the motor cortex at relatively short latency. To shed some light on its neural basis, we studied the visuomotor interaction using paired transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were recorded from the right first dorsal interosseous in sixteen healthy volunteers. A conditioning stimulus (CS) was applied over the phosphene hotspot of the visual cortex, followed by a test stimulus over the left primary motor cortex (M1) with a random interstimulus interval (ISI) in range 12-40 ms. The effects of paired stimulation were retested during visual and auditory reaction-time tasks (RT). Finally, we measured the effects of a CS on short-interval intracortical inhibition (SICI). At rest, a CS over the occiput significantly (P < 0.001) suppressed test MEPs with an ISI in the range 18-40 ms. In the visual RT, inhibition with an ISI of 40 ms (but not 18 ms) was replaced by a time-specific facilitation (P < 0.001), whereas, in the auditory RT, the CS no longer had any effect on MEPs. Finally, an occipital CS facilitated SICI with an ISI of 40 ms (P < 0.01). We conclude that it is possible to study separate functional connections from visual to motor cortices using paired-TMS with an ISI in the range 18-40 ms. The connections are inhibitory at rest and possibly mediated by inhibitory interneurones in the motor cortex. The effect with an ISI of 40 ms reverses into facilitation during a visuomotor RT but not an audiomotor RT. This suggests that it plays a role in visuomotor integration.

Effects of anodal transcranial direct current stimulation on visually guided learning of grip force control.

Anodal transcranial Direct Current Stimulation (tDCS) has been shown to be an effective non-invasive brain stimulation method for improving cognitive and motor functioning in patients with neurological deficits. tDCS over motor cortex (M1), for instance, facilitates motor learning in stroke patients. However, the literature on anodal tDCS effects on motor learning in healthy participants is inconclusive, and the effects of tDCS on visuo-motor integration are not well understood. In the present study we examined whether tDCS over the contralateral motor cortex enhances learning of grip-force output in a visually guided feedback task in young and neurologically healthy volunteers. Twenty minutes of 1 mA anodal tDCS were applied over the primary motor cortex (M1) contralateral to the dominant (right) hand, during the first half of a 40 min power-grip task. This task required the control of a visual signal by modulating the strength of the power-grip for six seconds per trial. Each participant completed a two-session sham-controlled crossover protocol. The stimulation conditions were counterbalanced across participants and the sessions were one week apart. Performance measures comprised time-on-target and target-deviation, and were calculated for the periods of stimulation (or sham) and during the afterphase respectively. Statistical analyses revealed significant performance improvements over the stimulation and the afterphase, but this learning effect was not modulated by tDCS condition. This suggests that the form of visuomotor learning taking place in the present task was not sensitive to neurostimulation. These null effects, together with similar reports for other types of motor tasks, lead to the proposition that tDCS facilitation of motor learning might be restricted to cases or situations where the motor system is challenged, such as motor deficits, advanced age, or very high task demand.

Functional Outcomes at Age 7 Years of Moderate Preterm and Full Term Children Born Small for Gestational Age

To compare functional outcomes of 7-year-old (school-age) children born small for gestational age (SGA; ie, a birth weight z score ≤ -1 SD), with appropriate for gestational age (AGA) peers, born moderately preterm or full term. Data were collected as part of the Longitudinal Preterm Outcome Project study, a community-based, prospective cohort study of 336 AGA and 42 SGA born children (median gestational age 35 weeks, range 31-41). Of the SGA children, 32 were moderately preterm, 10 were full term; of the AGA, these numbers were 216 and 120, respectively. At 6.9 years, we assessed intelligence, verbal memory, attention, visuomotor integration, and motor skills and we collected the parent-reported executive functioning. We compared the outcomes of the SGA children with those of their AGA peers. The performance of SGA children was similar to that of their AGA peers, except for attention control which was abnormal more often in SGA children (OR 3.99, 95% CI 1.32-12.12). The IQ of SGA children was 3 points lower, but this difference failed to reach significance. At school age, children born SGA have a greater risk of abnormal test scores on attention control than children born AGA, independent of gestational age. Their motor and many other cognitive functions are similar. The impact of these outcomes seems limited. Nevertheless, the consequences for school performance deserve attention.

Bridging the gap between motor imagery and motor execution with a brain–robot interface

According to electrophysiological studies motor imagery and motor execution are associated with perturbations of brain oscillations over spatially similar cortical areas. By contrast, neuroimaging and lesion studies suggest that at least partially distinct cortical networks are involved in motor imagery and execution. We sought to further disentangle this relationship by studying the role of brain-robot interfaces in the context of motor imagery and motor execution networks.Twenty right-handed subjects performed several behavioral tasks as indicators for imagery and execution of movements of the left hand, i.e. kinesthetic imagery, visual imagery, visuomotor integration and tonic contraction. In addition, subjects performed motor imagery supported by haptic/proprioceptive feedback from a brain–robot-interface. Principal component analysis was applied to assess the relationship of these indicators. The respective cortical resting state networks in the α-range were investigated by electroencephalography using the phase slope index.We detected two distinct abilities and cortical networks underlying motor control: a motor imagery network connecting the left parietal and motor areas with the right prefrontal cortex and a motor execution network characterized by transmission from the left to right motor areas. We found that a brain–robot-interface might offer a way to bridge the gap between these networks, opening thereby a backdoor to the motor execution system. This knowledge might promote patient screening and may lead to novel treatment strategies, e.g. for the rehabilitation of hemiparesis after stroke.

Visuomotor deficits during locomotion in previously concussed athletes 30 or more days following return to play.

Current protocols for returning athletes to play (RTP) center around resolution of physical symptoms of concussion. However, recent research has identified that balance and cognitive deficits persist beyond physical symptom recovery. Protocols that involve testing dynamic balance and visuomotor integration have been recommended as potential tools for better understanding of length of impairment following concussion. A dynamic, visuomotor paradigm was undertaken in the current study to assess decision making in athletes who had sustained a concussion >30 days before study participation and had been cleared to RTP (N = 10). Two obstacles created a gap that varied between 0.6 and 1.8× participants' individual shoulder width in open space. Participants made decisions to navigate through or deviate around the gap created by the two obstacles. The results revealed that previously concussed athletes were highly variable in their decision making and demonstrated variable Medial‐Lateral (ML) center of mass (COM) control when approaching the obstacles, when compared with nonconcussed, age‐matched controls. As such, they showed poor visuomotor control and decision making, as well as poor dynamic stability compared to controls. Visuomotor deficits were persistent in the sample of previously concussed individuals, well beyond deficits identified by current RTP standards. This study suggests that dynamic, visuomotor integration tasks may be of benefit to increase rigor in RTP protocols and increase safety of athletes returning to sport.

Occipital cortical thickness in very low birth weight born adolescents predicts altered neural specialization of visual semantic category related neural networks

Very low birth weight (VLBW) premature born infants have a high risk to develop visual perceptual and learning deficits as well as widespread functional and structural brain abnormalities during infancy and childhood. Whether and how prematurity alters neural specialization within visual neural networks is still unknown. We used functional and structural brain imaging to examine the visual semantic system of VLBW born (<1250g, gestational age 25–32 weeks) adolescents (13–15 years, n=11, 3 males) and matched term born control participants (13–15 years, n=11, 3 males). Neurocognitive assessment revealed no group differences except for lower scores on an adaptive visuomotor integration test. All adolescents were scanned while viewing pictures of animals and tools and scrambled versions of these pictures. Both groups demonstrated animal and tool category related neural networks. Term born adolescents showed tool category related neural activity, i.e. tool pictures elicited more activity than animal pictures, in temporal and parietal brain areas. Animal category related activity was found in the occipital, temporal and frontal cortex. VLBW born adolescents showed reduced tool category related activity in the dorsal visual stream compared with controls, specifically the left anterior intraparietal sulcus, and enhanced animal category related activity in the left middle occipital gyrus and right lingual gyrus. Lower birth weight of VLBW adolescents correlated with larger thickness of the pericalcarine gyrus in the occipital cortex and smaller surface area of the superior temporal gyrus in the lateral temporal cortex. Moreover, larger thickness of the pericalcarine gyrus and smaller surface area of the superior temporal gyrus correlated with reduced tool category related activity in the parietal cortex. Together, our data suggest that very low birth weight predicts alterations of higher order visual semantic networks, particularly in the dorsal stream. The differences in neural specialization may be associated with aberrant cortical development of areas in the visual system that develop early in childhood.

Persistence of visuo-constructional and executive deficits in adolescents after open-heart surgery

This study assesses whether previously reported performance deficiencies in visuo-constructional and executive functions, using the Rey-Osterrieth Complex Figure Test (ROCFT) in pediatric patients with congenital heart disease (CHD), persist into adolescence. 53 adolescent CHD patients (mean age 13.7) and 39 healthy controls (mean age 14.1) participated. ROCFT performance was measured by three different scoring methods, focusing either on quantitative (Meyers & Meyers, 1995), qualitative (Wallon & Mesmin, 2009), or both performance aspects (Bernstein & Waber, 1996). Potential confounders (i.e., intelligence and visuomotor integration) and surgery-related risk factors were included in the data analysis. Adolescents with CHD demonstrated immature copy and recall approaches on the ROCFT using the qualitative system by Wallon and Mesmin (p<.001). Memory performance was also predicted by Bernstein and Waber scores (p<.03), whereas group differences were not significant according to the other scoring methods. Intelligence and visuomotor skills, but not surgery-related risk factors, were positively correlated with ROCFT performance (each p<.02). Interpretation: Visuoconstructional and executive deficiencies could be found in adolescent patients with CHD. However, not all ROCFT scoring methods were equally apt to detect group differences: especially the qualitative scoring method developed by Wallon and Mesmin seems sufficiently sensitive to detect long-lasting visuo-constructional and executive deficiencies in CHD patients.

학교기반 작업치료에 관한 체계적 고찰

목적 : 본 연구는 학교기반 작업치료 중재 및 평가에 관한 근거마련을 위하여 체계적 고찰을 실시하였다. 연구 방법 : 2000년 이후부터 2014년 6월까지 PubMed와 Ovid의 데이터베이스에서 school or children and occupational therapy의 검색용어를 사용하여 검색하여 총 14개의 연구를 선정하였다. 본문을 통해 대상연구의 근거수준, 대상자, 평가도구, 중재영역 및 방법과 효과를 분석하였다. 결과 : 대상자는 정상아동(64.3%)이 가장 많았고, 다음은 자폐(14.4%)이었다. 연령은 6~8세(35.7%)로 가장 많았고, 다음은 5~7세와 5~12세(14.4%)이었다. 중재영역은 글쓰기 및 소근육과 시운동 통합(68.8%)이 가장 많았고, 중재방법은 직접치료(71.4%)가 가장 많았다. 평가도구 분석결과, Beery-Buktenica Test of Visual-Motor Integration (14.9%)가 가장 많았고, 다음은 Bruininks-Oseretsky Test of Motor Proficiency (11.1%)이었다. 학교기반 작업치료의 중재효과에 대한 분석 결과, 시운동 통합, 학습 기술, 참여 수준, 소근육 운동, 놀이, 행동적 문제에서 효과가 있었다. 결론 : 본 연구를 통해 학교기반 작업치료의 중재, 대상자, 평가도구 및 효과에 대한 근거를 마련하였다. 이는 학교 기반 작업치료 임상과 연구의 기초자료로 활용할 수 있을 것이다. Objective : This study was conducted to determine effects of school-based occupational therapy through a systematic review Methods : We systematically reviewed studies published in PubMed and Ovid from 2000 to June 2014 using keyword 'school' or 'children' and 'occupational therapy'. Fourteen studies were selected. The level of evidence, participants, assessment, intervention area, method and effects were analyzed by reviewing full text. Results : The most group and age of participants were normal child with fine motor difficulties and 6~8 years old in selected studies. The most target area of intervention was handwriting, fine motor and visuo-motor integration (68.8%) and the most method was direct treatment (71.4%). The top on the assessment was Beery-Buktenica Test of Visual-Motor Integration (14.9%) and next was Bruininks-Oseretsky Test of Motor Proficiency (11.1%). Effects of school based occupational therapy were founded in the visual motor integration, learning skill, level of participation, fine motor, play and behavioral problem. Conclusion : This systematic review provides evidence concerning the participants, intervention, assessment and effects of school based occupational therapy. It should be used for basic data for the research and practice of school-based occupational therapy.

Functional connectivity of primary motor cortex is dependent on genetic burden in prodromal Huntington disease.

Subtle changes in motor function have been observed in individuals with prodromal Huntington disease (prHD), but the underlying neural mechanisms are not well understood nor is the cumulative effect of the disease (disease burden) on functional connectivity. The present study examined the resting-state functional magnetic resonance imaging (rs-fMRI) connectivity of the primary motor cortex (M1) in 16 gene-negative (NEG) controls and 48 gene-positive prHD participants with various levels of disease burden. The results showed that the strength of the left M1 connectivity with the ipsilateral M1 and somatosensory areas decreased as disease burden increased and correlated with motor symptoms. Weakened M1 connectivity within the motor areas was also associated with abnormalities in long-range connections that evolved with disease burden. In this study, M1 connectivity was decreased with visual centers (bilateral cuneus), but increased with a hub of the default mode network (DMN; posterior cingulate cortex). Changes in connectivity measures were associated with worse performance on measures of cognitive-motor functioning. Short- and long-range functional connectivity disturbances were also associated with volume loss in the basal ganglia, suggesting that weakened M1 connectivity is partly a manifestation of striatal atrophy. Altogether, the results indicate that the prodromal phase of HD is associated with abnormal interhemispheric interactions among motor areas and disturbances in the connectivity of M1 with visual centers and the DMN. These changes may, respectively, contribute to increased motor symptoms, visuomotor integration problems, and deficits in the executive control of movement as individuals approach a manifest diagnosis.

Mapping genetically controlled neural circuits of social behavior and visuo-motor integration by a preliminary examination of atypical deletions with Williams syndrome.

In this study of eight rare atypical deletion cases with Williams-Beuren syndrome (WS; also known as 7q11.23 deletion syndrome) consisting of three different patterns of deletions, compared to typical WS and typically developing (TD) individuals, we show preliminary evidence of dissociable genetic contributions to brain structure and human cognition. Univariate and multivariate pattern classification results of morphometric brain patterns complemented by behavior implicate a possible role for the chromosomal region that includes: 1) GTF2I/GTF2IRD1 in visuo-spatial/motor integration, intraparietal as well as overall gray matter structures, 2) the region spanning ABHD11 through RFC2 including LIMK1, in social cognition, in particular approachability, as well as orbitofrontal, amygdala and fusiform anatomy, and 3) the regions including STX1A, and/or CYLN2 in overall white matter structure. This knowledge contributes to our understanding of the role of genetics on human brain structure, cognition and pathophysiology of altered cognition in WS. The current study builds on ongoing research designed to characterize the impact of multiple genes, gene-gene interactions and changes in gene expression on the human brain.

Neurocognitive functioning in children and adolescents at the time of type 1 diabetes diagnosis: associations with glycemic control 1 year after diagnosis.

To determine whether impairments in neurocognitive functioning are detectable at type 1 diabetes diagnosis and associated with subsequent glycemic control. Children/adolescents (N = 147) aged 5-18 years completed neuropsychological testing during their inpatient hospitalization for new-onset type 1 diabetes. Test scores were compared with normative data using one-sample Student t tests. Children with onset before 8 years of age were compared with children aged 9-18 years using ANOVA, and associations between neurocognitive performance at diagnosis and glycemic control 1 year postdiagnosis were examined using regression analyses. Children with type 1 diabetes performed significantly below expectations on most neurocognitive measures (P values <0.0001), with large decrements from the normative mean evident in psychomotor speed (>1 SD), visuomotor integration (0.7 SD), and phonemic fluency (0.8 SD). High incidence of impairment (scores less than second percentile) was evident on all tasks except digit span. Dominant-hand psychomotor speed was significantly associated with poor glycemic control (A1C ≥9.5% [80 mmol/mol]; P = 0.032) 1 year postdiagnosis, controlling for race/ethnicity, sex, and reading ability. Impaired psychomotor speed was associated with a 0.77% increase in mean A1C (8.4 mmol/mol). Deficits were evident in neurocognitive functioning within days of diabetes diagnosis that were associated with diabetes outcomes over 1 year postdiagnosis. Impairment was most apparent in psychomotor speed, consistent with research implicating damage to posterior white matter tracts and associated gray matter regions in type 1 diabetes. Psychomotor impairment may be an early marker for a broader neurobehavioral vulnerability that has implications for long-term diabetes management.

Longitudinal evaluation of cognitive functioning in pediatric multiple sclerosis: report from the US Pediatric Multiple Sclerosis Network

Background: Approximately one-third of those with pediatric-onset multiple sclerosis (MS) experience cognitive impairment. Less is known concerning their change in cognitive functioning over time. Objective: Changes in cognitive function over time were measured in the largest pediatric cohort to date through the US Network of Pediatric MS Centers. Methods: A total of 67 individuals with pediatric MS (n=62) or clinically isolated syndrome (CIS, n=5), ranging from 8–17 years of age (mean age±standard deviation (SD)=14.37±2.02) completed initial and follow-up neuropsychological testing after an average of 1.64±0.63 years apart. The nine tests administered measure general intellect, attention and working memory, verbal memory, visuomotor integration, language, and executive functioning. Results: Rate of impairment (having one-third or more scores in the impaired range) was 37% at baseline and 33% at follow-up. Tests commonly impaired were measures of visuomotor integration, speeded processing, and attention. Most tested did not decline over two years. There was no clear pattern of change on any specific measure. Conclusion: Findings suggest that, over short timeframes, stable or even improved performances on measures of cognitive ability can occur. Pediatric MS may instead prevent expected age-related cognitive gains.

Positive Association of Video Game Playing with Left Frontal Cortical Thickness in Adolescents

Playing video games is a common recreational activity of adolescents. Recent research associated frequent video game playing with improvements in cognitive functions. Improvements in cognition have been related to grey matter changes in prefrontal cortex. However, a fine-grained analysis of human brain structure in relation to video gaming is lacking. In magnetic resonance imaging scans of 152 14-year old adolescents, FreeSurfer was used to estimate cortical thickness. Cortical thickness across the whole cortical surface was correlated with self-reported duration of video gaming (hours per week). A robust positive association between cortical thickness and video gaming duration was observed in left dorsolateral prefrontal cortex (DLPFC) and left frontal eye fields (FEFs). No regions showed cortical thinning in association with video gaming frequency. DLPFC is the core correlate of executive control and strategic planning which in turn are essential cognitive domains for successful video gaming. The FEFs are a key region involved in visuo-motor integration important for programming and execution of eye movements and allocation of visuo-spatial attention, processes engaged extensively in video games. The results may represent the biological basis of previously reported cognitive improvements due to video game play. Whether or not these results represent a-priori characteristics or consequences of video gaming should be studied in future longitudinal investigations.

Visuomotor Function in Children Treated for Acute Lymphoblastic Leukaemia With Chemotherapy Only

This study aimed to evaluate visuomotor function in children treated for acute lymphoblastic leukaemia (ALL). The performance of 64 children, 1–7 years post-chemotherapy for ALL, was compared to that of their healthy peers (n = 56) on visuomotor integration (VMI) and motor coordination (MC) tasks. Children posttreatment for ALL displayed significantly reduced VMI, but not MC, performances as compared to controls. Children treated on chemotherapy-only ALL regimes are at heightened risk for visuomotor integration deficits. Monitoring of visuomotor skills and implementation of appropriate interventions targeting higher level visuomotor integration skills should form an important component of any ALL long-term effects program.

Resting-state cortical connectivity predicts motor skill acquisition

Many studies have examined brain states in an effort to predict individual differences in the capacity for learning, with overall moderate results. The present study investigated how measures of cortical network function acquired at rest using dense-array EEG (256 leads) predict subsequent acquisition of a new motor skill. Brain activity was recorded in 17 healthy young subjects during 3min of wakeful rest prior to a single motor skill training session on a digital version of the pursuit rotor task. Practice was associated with significant gains in task performance (% time on target increased from 24% to 41%, p<0.0001). Using a partial least squares regression (PLS) model, coherence with the region of the left primary motor area (M1) in resting EEG data was a strong predictor of motor skill acquisition (R2=0.81 in a leave-one-out cross-validation analysis), exceeding the information provided by baseline behavior and demographics. Within this PLS model, greater skill acquisition was predicted by higher connectivity between M1 and left parietal cortex, possibly reflecting greater capacity for visuomotor integration, and by lower connectivity between M1 and left frontal–premotor areas, possibly reflecting differences in motor planning strategies. EEG coherence, which reflects functional connectivity, predicts individual motor skill acquisition with a level of accuracy that is remarkably high compared to prior reports using EEG or fMRI measures.

Sensory Processing and Visuo Motor Integration in Preschoolers: Understanding the Link

Objective : To comment on the correlation between VMI scores and the sensory processing of children in the age group 3-7 years Methodology : The typically developing children with no known cognitive, mental or physical affectation were assessed using the Beery's Visuo Motor Integration test (Short Form) and the Structured Clinical Observations of Sensory Processing. Results :There was a significant and positive relationship found between the VMI scores and the structured clinical observations of Diadokokinesis, Sequential Finger Touching, Protective extension, Praxis, Free Play and Play Preferences and Conscious and Automatic Eye Movements. Conclusion : There is a positive correlation between the visuo motor skills and sensory processing skills of children. Affectation of Visuo motor skills may be resultant of faulty sensory processing. The remediation programs for visuo motor skill affectations should therefore be structured after assessing the sensory processing of the child and keeping in background the sensory processing deficiencies of the child.

Pattern discrimination of neuroelectric waveforms evoked by synchronized visuo-motor integration.

Today, there is a significant demand for fast, accurate, and automated methods for the discrimination of latent patterns in neuroelectric waveforms. One of the main challenges is the development of efficient feature extraction tools to utilize the rich spatio-temporal information inherent in large scale human electrocortical activity. In this paper, our aim is to isolate the most suitable feature extraction method for accurate classification of EEG data related to distinct modes of sensorimotor integration. Our results demonstrate that with some user-dependent input for feature space constraint, a simple classification framework can be developed to accurately distinguish between brain electrical activity patterns during two distinct conditions.

Predicting motor learning performance from Electroencephalographic data

BackgroundResearch on the neurophysiological correlates of visuomotor integration and learning (VMIL) has largely focused on identifying learning-induced activity changes in cortical areas during motor execution. While such studies have generated valuable insights into the neural basis of VMIL, little is known about the processes that represent the current state of VMIL independently of motor execution. Here, we present empirical evidence that a subject’s performance in a 3D reaching task can be predicted on a trial-to-trial basis from pre-trial electroencephalographic (EEG) data. This evidence provides novel insights into the brain states that support successful VMIL.MethodsSix healthy subjects, attached to a seven degrees-of-freedom (DoF) robot with their right arm, practiced 3D reaching movements in a virtual space, while an EEG recorded their brain’s electromagnetic field. A random forest ensemble classifier was used to predict the next trial’s performance, as measured by the time needed to reach the goal, from pre-trial data using a leave-one-subject-out cross-validation procedure.ResultsThe learned models successfully generalized to novel subjects. An analysis of the brain regions, on which the models based their predictions, revealed areas matching prevalent motor learning models. In these brain areas, the α/μ frequency band (8–14 Hz) was found to be most relevant for performance prediction.ConclusionsVMIL induces changes in cortical processes that extend beyond motor execution, indicating a more complex role of these processes than previously assumed. Our results further suggest that the capability of subjects to modulate their α/μ bandpower in brain regions associated with motor learning may be related to performance in VMIL. Accordingly, training subjects in α/μ-modulation, e.g., by means of a brain-computer interface (BCI), may have a beneficial impact on VMIL.

Frequency domain mediolateral balance assessment using a center of pressure tracking task

Since impaired mediolateral balance can increase fall risk, especially in the elderly, its quantification and training might be a powerful preventive tool. We propose a visual tracking task (VTT) with increasing frequencies (.3–2.0Hz) and with center of pressure as visual feedback as an assessment method. This mediolateral balance assessment (MELBA) consists of two tasks, tracking a predictable target signal to determine physical capacity and tracking an unpredictable target signal to determine sensorimotor integration limitations. Within and between sessions learning effects and reliability in balance performance descriptors in both tasks were studied in 20 young adults. Balance performance was expressed as the phase-shift (PS) and gain (G) between the target and CoP in the frequency domain and cut-off frequencies at which the performance dropped. Results showed significant differences between the MELBA tasks in PS and G indicating a lower delay and higher accuracy in tracking the predictable target. Significant within and between sessions learning effects for the same measures were found only for the unpredictable task. Reliability of the cut-off frequencies at which PS and G performance declined and the average values within cut-off frequencies was fair to good (ICC .46–.66) for the unpredictable task and fair to excellent for the predictable task (ICC .68–.87). In conclusion, MELBA can reliably quantify balance performance using a predictable VTT. Additionally, the unpredictable tasks can give insight into the visuomotor integration mechanisms controlling balance and highlights MELBA's potential as a training tool.

Early Visuomotor Integration Processes Induce LTP/LTD-Like Plasticity in the Human Motor Cortex

To investigate whether visuomotor integration processes induce long-term potentiation (LTP) and depression (LTD)-like plasticity in the primary motor cortex (M1), we designed a new paired associative stimulation (PAS) protocol coupling left primary visual area (V1) activation achieved by hemifield visual evoked potentials (VEPs) and transcranial magnetic stimulation (TMS) over the left M1, at specific interstimulus intervals (ISIs), delivered at 1 Hz (V-PAS). Before and after V-PAS, we measured motor evoked potentials (MEPs). To clarify the mechanisms underlying V-PAS, we tested the effect of 1-Hz repetitive TMS (rTMS), 0.25-Hz V-PAS and rTMS, and a shorter 0.25-Hz V-PAS protocol. To examine V-PAS with contralateral V1 activation, we delivered V-PAS activating the right V1. To clarify whether V-PAS increases V1 activity or parieto- and premotor-to-M1 connectivity, before and after V-PAS, we examined VEPs and MEPs evoked by paired-pulse techniques. V-PAS increased, decreased, or left MEPs unchanged according to the ISI used. After 1-Hz rTMS MEPs decreased. Although 0.25-Hz rTMS elicited no aftereffect, 0.25-Hz V-PAS modulated MEPs according to the ISI used. The short 0.25-Hz V-PAS protocol left MEPs unchanged. Contralateral V-PAS inhibited MEPs. After V-PAS, VEPs remained unchanged and the premotor-to-M1 inhibitory connections decreased. V-PAS induces M1 LTP/LTD-like plasticity by activating premotor-to-motor connections.