Pilot study to explore poor visual searching capabilities in children with ADHD: a tablet-based computerized test battery study.

Aim: The frequent visual attention deficiency reported in children with attention-deficit/hyperactivity disorder (ADHD) could represent a relevant biomarker but robust estimates of such cognitive impairment in clinical populations remained challenging. To assess visual attention impairment in children ADHD using a new design tablet-based computerized test battery which allowed objective recording of visual search performances.Methods: Forty-nine children with ADHD and their IQ- and age-matched typically developmental (TD) children were enrolled in the study. Visual attention abilities were estimated by using the computerized modified barrage test developed by Metrisquare. We analyzed the time spent to achieve the whole battery and, the errors and omissions done by each child during each of the three sub-tasks.Results: We observed a significant association between the load of sustained attention requested to perform a sub-task and the numbers of errors and omissions made by the children whatever the group considered. During the most stringent sub-task in term of visual attention engagement, children with ADHD displayed more significant errors and omissions when compared to IQ- and age-matched controls. This effect was not mediated by the time spent to perform the task since we did not report any significant difference between groups.Conclusion: The different performance of the most stringent sub-task observed in children with ADHD could be due to their deficient neural activity in frontal areas responsible of visual endogenous attention needed for difficult visual searching tasks. This cognitive battery could be a useful instrument to estimate visual attention impairment in children with ADHD.HIGHLIGHTSWe assessed if a new design tablet-based computerized test battery would allow objective recording of visual search performances.We observed that children with ADHD made significantly more errors and omissions with respect to age-, sex- matched controls during the most stringent sub-task in terms of visual attention engagementThe tablet-based computerized test battery could be a promising tool to objectively estimate abnormal attention search impairment in ADHD.

Immature brain structures were associated with poorer eye movement performance at 8 years of age in preterm born children.

AIM: Eye movements have rarely been explored in preterm born children. The aim of this study was to compare horizontal eye movements in children born preterm and full term when they reached 8 years of age. METHODS: Eye movements were recorded in 24 preterm born children (18 boys) and 26 matched controls (19 boys), recruited by a French hospital, using an eye tracker. This identified different types of visually guided saccades, namely step, gap, overlap and antisaccades and pursuit eye movements. The saccades task measured the latency and the percentage of anticipatory and express saccades and errors. The pursuit task measured the gain and percentage of intrusive saccades. RESULTS: This study confirmed that children born at 24-28 weeks of gestation demonstrated a global deficit in inhibitory processes compared to children born full term. The saccades were less precise in the preterm group, anticipatory and express saccades were elevated and there was a high occurrence of intrusive saccades during pursuit movements. CONCLUSION: These findings suggest that preterm born children have immature brain structures, particularly the parietal and frontal cortexes that are responsible for both saccade and pursuit performance. These could have been the cause of the abnormal inhibitory control measured in this study.

Poor visuo-spatial orientation and path memorization in children with dyslexia.

PURPOSE: Given the importance of spatial representation and navigation in the natural environment and the presence of sensory motor integration impairment in dyslexic children the aim of this study was to explore the capability in spatial orientation task in dyslexic children. MATERIALS AND METHODS: We included forty children: 26 dyslexic children (mean age: 10.1 ± 0.3 years old) and 14 typically developing (TD) children (mean age: 10.1 ± 0.4 years old). Children have to walk on an unguided isosceles rectangle triangle of 3 meters that was marked on the ground of a room, during two visual conditions: eyes open and eyes closed. Their paths were recorded using the HTC Vive system (Base + Trackers) with a refresh rate of 90 Hz with accuracy < 0.05 mm. RESULTS: Results underlined that both groups of children reported poor performance during eyes closed condition. Moreover, dyslexic children, reported poor spatial orientation capabilities in the most difficult conditions, that is during reproduction of hypotenuse and angle of 45 deg. CONCLUSIONS: We suggested that visual information is important during walking; the poor body orientation observed in dyslexic children could be due to a deficient integration of the sensorial inputs (visual, vestibular and proprioceptive). Further studies testing vestibular/cerebellar rehabilitation could be useful for these kinds of children.HighlightsChildren with dyslexia showed poor spatial orientation capabilities compared to typically developing children, particularly when visual inputs are not available and in the most difficult conditions (like rotation of the body).Poor motor abilities reported by children with dyslexia could be due to cerebrocerebellar pathways impairments.

The Developmental Eye Movement Test in French Children.

SIGNIFICANCE: This study reported that the Developmental Eye Movement (DEM) test for French children is similar to the American ones and that all parameters of the DEM test improve up to the age of 10 years. PURPOSE: The DEM test has been normalized for several different populations of children, but there are no published norms for French children. This study aimed to determine values of the DEM test for French-speaking children. METHODS: A total of 327 children from 6 to 12 years of age participated in the study. The DEM test was administered as outlined in the manual. RESULTS: Significant differences were found between the ages, and DEM test scores improved with age until about 10 years. Developmental Eye Movement test scores were similar to those reported in American children. CONCLUSIONS: Cortical and central structures responsible for oculomotor and attentional capabilities are developing until about 10 years of age, and that could explain the improvement of the DEM test score up to this age. Furthermore, values of the DEM test in French children are similar to the American ones that are currently used as norms by French clinicians.

Dyslexic children need more robust information to resolve conflicting sensory situations.

The study involved investigating dyslexic children's postural control responses when visual and somatosensory cues were separately manipulated. Twenty dyslexic and 19 nondyslexic children performed a trial by standing upright inside a moving room and another by lightly touching a moving bar. Both trials lasted 240 s with the following three different stimulus characteristics: low (pretransition), high (transition), and low amplitude (posttransition). Body sway magnitude and the relationship between the movement of the room/bar surface and body sway were examined. When compared to nondyslexic children, dyslexic children oscillated with higher magnitude in the transition and posttransition under visual and somatosensory manipulation; their sway was more influenced by visual manipulation in the transition and posttransition, and they used higher applied force levels in the somatosensory modality in all conditions. The results suggest that dyslexic children could not efficiently reweight visual cues when compared to nondyslexic children. The same was not observed in the somatosensory cues when dyslexic children reduced the influence of the somatosensory stimulus. The proper use of somatosensory information was related to stronger acquired cues and higher applied forces as observed for dyslexic children. Dyslexic children experience difficulties in dynamically reweighting sensory cues although these types of difficulties are overcome when more informative sensory cues are provided.

Postural Control in Children with Dyslexia: Effects of Emotional Stimuli in a Dual-Task Environment.

The aim of this study was to compare the visual exploration strategies used during a postural control task across participants with and without dyslexia. We simultaneously recorded eye movements and postural control while children were viewing different types of emotional faces. Twenty-two children with dyslexia and twenty-two aged-matched children without dyslexia participated in the study. We analysed the surface area, the length and the mean velocity of the centre of pressure for balance in parallel with visual saccadic latency, the number of saccades and the time spent in regions of interest. Our results showed that postural stability in children with dyslexia was weaker and the surface area of their centre of pressure increased significantly when they viewed an unpleasant face. Moreover, children with dyslexia had different strategies to those used by children without dyslexia during visual exploration, and in particular when they viewed unpleasant emotional faces. We suggest that lower performance in emotional face processing in children with dyslexia could be due to a difference in their visual strategies, linked to their identification of unpleasant emotional faces. Copyright © 2017 John Wiley & Sons, Ltd.

Developmental study identifies the ages at which the processes involved in the perception of verticality and in postural stability occur.

AIM: The aim of this study was to understand the role played by visual information on the development of verticality and postural stability in healthy children. METHODS: The study comprised 66 healthy children from 4.0 to 15.7 years of age. Postural performances were recorded with a TechnoConcept platform. At the same time, the children's perception of subjective visual vertical (SVV) was recorded while they adjusted a vertical fluorescent line, either in the dark or in the presence of perturbing visual stimuli. Two testing control conditions without an SVV task were also performed by all of the children: static posturographic recording with open eyes and closed eyes. RESULTS: Postural measurements provided evidence of a correlation between the children's age and the tasks performed. Postural stability improved with age until eight to nine years, and SVV performance improved after 10-11 years. After these ages, postural and SVV capabilities did not change until at least 15 years of age. CONCLUSION: Our findings suggest that the maturation of cortical and central processes involved in both the perception of verticality and in postural stability took place during childhood. However, maturation occurred later for vertical perception, which could imply delayed maturation of sensory integration processes.

Spatial and temporal analyses of posture in strabismic children.

PURPOSE: To analyse postural performances of strabismic children, both in the spatial and the temporal domains, by wavelet transformation, comparing both stable and unstable situations. METHODS: Twenty-six strabismic children aged from 4 to 11 years old and 26 age-matched normal children participated in the study. Postural performances were evaluated using the Framiral® platform. Posture was recorded in the following conditions: eyes open fixating a target and eyes closed on stable and unstable platforms. RESULTS: For both strabismic and non-strabismic children, the surface and the mean velocity of the center of pressure (CoP) were significantly larger in the eyes closed on unstable platform condition, but this was much more pronounced in case of strabismus. Spectral power index and cancelling time were also found to be altered in strabismic children compared to non-strabismic children. CONCLUSIONS: This data demonstrates poor postural stability for both groups on an unstable platform with the eyes closed. However, strabismic children had significantly worse performance than non-strabismic children. Strabismic children also engage more energy to stabilize their posture by using visuo-vestibular sensory inputs to compensate their altered vision due to strabismus, in comparison to non-strabismic children.

Vertical saccades in children: a developmental study.

There are no studies exploring the development of vertical saccades in large populations of children. In this study, we examined the development of vertical saccades in sixty-nine children. Binocular eye movements were recorded using an infrared video oculography system [Mobile EBT(®), e(ye)BRAIN], and movements from both eyes had been analyzed. The gain and the peak velocity of vertical saccades show an up-down asymmetry. Latency value decreases with the age of children, and it does not depend on the direction of the saccades; in contrast, the gain and the peak velocity values of vertical saccades are stable during childhood. We suggest that the up-down asymmetry is developed early, or is innate, in humans. Latencies of vertical saccades develop with the age of children, in relationship with the development of the cortical network responsible for the saccade preparation. In contrast, the precision and the peak velocity are not age-dependent as they are controlled by the cerebellum and brainstem structures.

Visuo-Attentional and Phonological Deficits Explored in French Students with Dyslexia: Eye Movements Recorded during a Phonological Lexical Decision Task.

Whether dyslexia is caused by phonological or attentional dysfunction remains a widely debated issue. To enrich this debate, we compared the eye movements of 32 French university students with (14 students) and without (18 students) dyslexia while performing a delayed phonological lexical decision task on 300 visually presented stimuli. The processing stimuli involved either a lexical (i.e., words) or a non-lexical route relying on a grapheme-phoneme correspondence (pseudohomophones and pseudowords), while other stimuli involved only a visual search (consonant and symbol sequences). We recorded the number of fixations, the duration of the first fixation and the amplitude of saccades made on the stimuli. Compared to the controls, the participants with dyslexia made more fixations while reading regardless of the type of stimulus (lexical and non-lexical). Crucially, the participants with dyslexia exhibited longer first fixations in particular while reading phonologically challenging stimuli such as pseudohomophones and pseudowords compared to stimuli involving a simple visual search (consonants, symbols). Taken together, these results suggest that both visual and phonological impairments may be implicated in dyslexia, supporting the hypothesis that dyslexia is a multifactorial deficit.

Increased Semantic Memorization in Children with ADHD during a Paradigm of Motor Priming: Exploratory Findings.

AIM: The aim was to evaluate the effect of body actions on learning process, particularly semantic memory capabilities in drug-naïve children with attention deficit hyperactivity disorder (ADHD). METHOD: Thirty children had to listen to a story which was repeated three times in a row and then a fourth time five minutes later. After each listen, the child was asked what she/he remembered from the story. The whole sample was split randomly into three subgroups of equal IQ (mean 102.2 ± 12.7), age (mean age 8 ± 0.6 years), sex (ratio female to male 1:5) and severity of ADHD symptoms (34.2 ± 7.4); a G1 "Freeze" subgroup, which implied listening to the story while sitting on a chair without moving; a G2 "Minimal" subgroup, which implied listening to the story while sitting on a chair but free movement was allowed; a G3 "Prescribed movement" subgroup, which implied listening to the story standing up, while copying the experimenter movements that mimicked the actions told in the story. RESULTS: Although our sample was limited in size, interestingly, children in the G3 subgroup showed the highest short-term semantic memory retention compared to G1. In all subgroups, repetition allowed an increase in performance. CONCLUSIONS: Our exploratory findings stress the positive role of movement in children with ADHD to increase semantic memorization. Hyperactivity may counteract the deficit of memorization related to attention impairment in children with ADHD. Our results may encourage parents or teachers to allow children with ADHD to move around during short-term memory-retention tasks.

Differing effects of prosaccades and antisaccades on postural stability.

The goal of the study was to examine the effect of different types of eye movements on postural stability. Ten healthy young adults (25 ± 3 years) participated in the study. Postural control was measured by the TechnoConcept© platform and recorded in Standard Romberg and Tandem Romberg conditions while participants performed five oculomotor tasks: two fixation tasks (central fixation cross, without and with distractors), two prosaccade tasks toward peripheral targets displayed 4° to the left or to the right of the fixation cross (reactive saccades induced by a gap 0 ms paradigm and voluntary saccades induced by an overlap 600 ms paradigm) and one antisaccade task (voluntary saccade made in the opposite direction of the visual target). The surface, the length, and the mean speed of the center of pressure were analyzed. We found that saccadic eye movements improved postural stability with respect to the fixation tasks. Furthermore, antisaccades were found to decrease postural stability compared to prosaccades (reactive as well as voluntary saccades). This result is in line with the U-shaped nonlinear model described by Lacour et al. (Neurophysiol Clin 38:411-421, 2008), showing that a secondary task performed during a postural task could increase (prosaccade task) or decrease (antisacade task) postural stability depending on its complexity. We suggest that the different degree of attentional resources needed for performing prosaccade or antisaccade tasks are, most likely, responsible for the different effect on postural control.

Postural control in strabismic children versus non strabismic age-matched children.

BACKGROUND: Several studies have shown that achieving a dual task modifies postural control; however, their results are conflicting. The goal of the present study is to compare the effect of a simple task (eye fixation) to the effect of a dual task (saccadic eye movements) on postural balance in strabismic and in non strabismic children. METHODS: Postural stability was recorded with a platform (Techno Concept©) in ten strabismic children aged from 5.4 to 13.8 years (mean age: 8.8 ± 2.5 years). Data were compared to that of ten age-matched non strabismic control children. We analyzed the surface area, the length and the mean speed of the center of pressure (CoP). RESULTS: Strabismic children are more instable than control children. The surface (340 mm(2)), the length (402 mm) and the mean speed (16 mm/s) of the CoP are significantly higher in strabismic children than in control children (160 mm(2), 280 mm and 11 mm/s, respectively). In addition, both strabismic and control children have a better postural control during saccades than during a fixation task. Surface, length and mean speed of the CoP are significantly reduced during the saccade task (214 mm(2), 306 mm and 12.5 mm/s, respectively) than during the fixation task (285 mm(2), 376 mm and 14.8 mm/s, respectively). CONCLUSIONS: Abnormal postural control in strabismic children could be due to their visual deficits. The postural improvement observed in a dual task (saccades) vs. a simple task (fixation) might be due to the fact that postural control becomes more automatic during saccadic eye movements.

Postural and Proprioceptive Deficits Clinically Assessed in Children with Reading Disabilities: A Case-Control Study.

Several studies have reported motor deficiencies in children with dyslexia, in line with the cerebellar deficit theory. In the present study, we explored whether tests used by physiotherapists during clinical evaluation were able to report motor deficits in a group of fifty-six dyslexic children (mean age 10.9 ± 0.2 years old) compared to a group of thirty-eight non-dyslexic children (mean age 11.2 ± 0.4 years old). The occurrence of instability on an unstable support; spinal instability in the sagittal, frontal and horizontal plane; head-eye discoordination; and poor eye stability were clinically assessed in the two groups of children. All such measures were found to be significantly more frequent in dyslexic than in non-dyslexic children (p < 0.001, p < 0.05, p < 0.001 and p < 0.001, respectively, for occurrence of instability on an unstable support, spinal instability, head-eye discoordination and poor eye stability). These results, firstly, confirmed the poor motor control of dyslexic children, suggesting deficient cerebellar integration. Secondly, for the first time, we reported that simple tests that can be done by pediatricians and/or during a clinical routine evaluation could be useful to discriminate children with reading difficulties. The tests used in this study could be a reference for a first exploration of motor deficiencies in children with dyslexia that can be easily assessed by clinicians and/or physiotherapists.

Dysfunction in inhibition and executive capabilities in children with autism spectrum disorder: An eye tracker study on memory guided saccades.

BACKGROUND: Dysmetria in children with autism spectrum disorders is considered depend on executive dysfunctions. To explore the impact of inhibitory control and working memory on oculomotor performance in children with autism spectrum disorder (ASD), we used the memory guided saccade (MGS) paradigm. METHOD: We enrolled in our study a group of 26 children with ASD and in a group of 26 children age-, sex-, and IQ-matched of with typically development, using only one single delay period and one single stimulus amplitude. We recorded with a video eye-tracker system- the latency and the accuracy of the MGS as well as the number of anticipatory saccades during the MGS paradigm. RESULTS: Children with ASD displayed significant increased latency (p < .01), decreased amplitude of memory guided saccades (p < .01) and an elevated number of anticipatory saccades (p < .003), when compared to age-, sex-, IQ- matched children with typical development. CONCLUSION: These abnormalities may underline the executive dysfunctions frequently reported in ASD: the increased latency and the decreased amplitude of memory guides saccades may be related to planning and working memory impairments; the increased number of anticipatory saccades may be linked to a deficit in inhibitory control.

Inhibition functions can be improved in children with autism spectrum disorders: An eye-tracking study.

Cognitive remediation therapy interventions could improve cognitive functioning in subjects with autism. To investigate the benefit of a short cognitive training rehabilitation in children with autism spectrum disorder (ASD) on pursuit and fixation performances. We recruited two groups (G1 and G2) of 30 children with ASD, sex-, IQ- and age-matched (mean 11.6 ± 0.5 years), and pursuit and fixation eye movements were recorded twice at T1 and T2. Between T1 and T2, a 10-min cognitive training was performed by the G1 group only, whereas the G2 group had a 10-min of rest. For all children with ASD enrolled in the study, there was a positive correlation between restricted and repetitive behaviour scores of both Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) and the number of saccades recorded during the fixation task at T1. At T1, oculomotor performances were similar for both groups of ASD children (G1 and G2). At T2, we observed a significant reduction in the number of saccades made during both pursuit and fixation tasks. Our findings underlined the importance to promote cognitive training rehabilitation for children with ASD, leading to a better performance in inhibitory and attention functioning responsible for pursuit and fixation eye movement's performance.

Motor Capabilities in Children with ADHD Are Improved after Brief Visuopostural Training.

Children with ADHD show poor motor control. The aim of the present study was to test whether children with ADHD improved their motor performances (oculomotor as well as posture) after a short visuopostural training period. Two groups (G1 trained and G2 non-trained), each comprising 15 children with ADHD matched in IQ (intelligence quotient), sex, and age, participated in the study. Eye movements and postural sway were measured before (T1) and after (T2) 10 min of visuopostural training for the trained group and after 10 min of resting for the non-trained group. Training consisted of a visual search task performed while the child was standing on an unstable platform. At T1, oculomotor and postural abilities were statistically similar for both groups of children with ADHD (trained and non-trained). At T2, significant improvements in both oculomotor and postural capabilities were observed for the trained group but not for the non-trained group. These findings suggest that a short visuopostural training period could help children with ADHD to learn how to focus their visual attention in order to improve motor performance. Visuopostural training could allow a better integration of sensory inputs via central mechanisms, leading to improvement in both oculomotor and postural control. Further studies on a larger number of children with ADHD will be needed to confirm these findings and explore the eventual possible persistence of the training effect.

Saccadic eye movements in children: a developmental study.

To our knowledge, there are no studies exploring the development of voluntary and reflexive saccades in children using different types of paradigms to investigate horizontal saccades. In the present study, we examined the development of horizontal saccades in children aged 6-15 years. Binocular eye movements were recorded using an infrared video-oculography system (mobileEBT(®), e(ye)BRAIN) in seventy-two children (aged 6-15). Several paradigms were used to stimulate reflexive and voluntary horizontal saccades: gap, step and overlap paradigms. Horizontal anti-saccades were also examined. In all paradigms, the latency of saccades decreased with the age of children and it did not depend on the direction of the saccades (left/right); the error rate in the anti-saccade task decreased with age; the gain of horizontal saccades improved with age; the peak velocity of horizontal saccades was stable throughout childhood. We conclude that saccadic performances are influenced by age and cortical circuits responsible for the preparation of reflexive or voluntary saccades are completed at 12 years old. These data could be used as reference values for further studies dealing with pathologic development.

Re-alignment of the eyes, with prisms and with eye surgery, affects postural stability differently in children with strabismus.

AIM: The purpose of the study was to examine the effect of eye re-alignment (after wearing prisms and after eye surgery) on postural stability in children with strabismus. METHODS: Nine children with strabismus (6-13 years old) participated in the study. A posturography platform (TechnoConcept) was used to examine posture in quiet stance at two distances: steady fixation of a target at near distance (40 cm) and at far distance (200 cm). Four different conditions were tested: with and without prisms before eye surgery, and twice after eye surgery. RESULTS: The surface of the CoP increased after wearing prisms (540 mm(2) compared to the condition without prisms (462 mm(2)); in contrast, eye surgery reduced the surface of the CoP, leading to improved postural control (454 mm(2) and 401 mm(2), respectively, in the post 1 and post 2 surgery condition). Unlike normal children, strabismic children showed no improvement in postural control at near distance. CONCLUSIONS: Binocular visual and motor changes affect body sway; adaptive mechanisms induced by eye re-alignment after surgery allow improved postural control. The absence of dependency on distance in postural stability in strabismic children could be due to their impaired depth perception and to the poor integrity of the visual signal required to control posture.

Interaction between Feet and Gaze in Postural Control.

In the last decade, the number of postural studies in humans, in particular on deficits in postural control in patients, has increased. In the present article, we review studies on postural control with a particular focus on the role of foot and visual inputs in a quiet postural stance. A search and synthesis of articles identified through the electronic databases Scopus, Web of Science, EBSCO, PubMed, and ResearchGate published until 2021 was performed. The aim of this review is to provide reference values for further studies dealing with postural control in both healthy and pathologic subjects and to encourage the development of suitable protocols that take into account the specificity of the different systems responsible for controlling human balance.