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This event-related potential (ERP) study aimed to examine at which point in the stream of four cognitive processes of word reading impairment occurs in dyslexic adults. Fourteen French native dyslexic speakers and eighteen matched controls performed a delayed phonological lexical decision task that consisted in deciding whether visual stimuli sounded like French words. Three hundred stimuli equally distributed among five experimental conditions (60 concrete French words, 60 pseudo-homophones, 60 pseudowords, 60 consonant and 60 symbol strings) were presented. Critically, two language processes involving phonological information, namely grapheme-to-phoneme conversion (N320) and memory retrieval of phonological information (Late Positive Complex) were impaired in dyslexics compared to controls. Moreover, lexical access (N400) was significantly modulated by six predictive variables assumed to be reliable markers of dyslexia. In contrast, and unexpectedly, the early processes of visual expertise for print (N170) appeared to operate in the same way in the two groups of participants. The locus of dyslexia is probably to be found primarily in some aspects of phonological processing during word reading. These findings support a clinical neurophysiology model postulating that at least two phonological processes during reading might be impaired in dyslexics, namely grapheme-to-phoneme conversion, and memory retrieval of phonological information. • Visual expertise for print is not necessarily impacted in dyslexic adults. • Reading impairment is observed primarily at the phonological level. • Dyslexic adults have an impaired graphene-to-phoneme conversion process (N320). • Retrieval of phonological information (LPC) is disturbed in dyslexic adults. • Lexical access is influenced by predictive variables of dyslexia. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare postural stability in a group of preterm-born children aged 4-6 years old and in a group of age-matched full-term control children by exploring both spatial and temporal analysis of the Center of Pressure (CoP). Twenty-nine children born prematurely (mean age: 5.38±0.17) and twenty-nine age-matched full-term control children participated in this study. Postural control was tested on both a stable and an unstable platform (from Framiral®) in three different visual conditions: eyes open fixating a target, eyes closed, and with vision perturbed by optokinetic stimulation. We observed a significant increase of both surface area and mean velocity of the CoP in pre-term children compared to full-term control children, particularly in an unstable postural condition. The spectral power indices increased significantly in pre-term children with respect to full-term control children, while the cancelling time was not different between the two groups of children tested. We suggested that poor postural stability observed in preterm children could be due to immaturity of the cortical processes (the occipital parietal prefrontal cortex) involved in motor control. Preterm children could have an inappropriate compensation of sensory inputs when they are tested in difficult postural and/or visual conditions. [ABSTRACT FROM AUTHOR]

Background Children with autism spectrum disorders (ASD) have poor postural stability. The objective of our study was to explore further postural capabilities in ASD children by measuring spatial as well as temporal displacement of the center of pressure using wavelet analysis. Method Thirty children with ASD (12.1 ± 2.9 years) and 30 sex-, age- and IQ-matched typically developing children participated in the study. We recorded postural control using Multitest, also called Balance Quest, Equilibre from Framiral ® in three viewing conditions (eyes open, eyes closed and with perturbed vision) and in two postural conditions (stable and unstable). Results Our results show that children with ASD displayed a deficit in postural stability in comparison with typically developing children, especially when sensory inputs are not all available. Conclusion Such poor postural control in children with ASD could be due to both an impairment in using sensorial inputs appropriately and a deficit in the ability to compensate for sensorial changes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Postural control in children with ADHD is poor. [•] This instability is probably due to cerebellar deficiencies. [•] Children with ADHD as well as control children improved postural sway when performing saccadic eye movements. [•] The beneficial effect of MPH treatment is perceptible in the surface area of the CoP. [Copyright &y& Elsevier]

Highlights: [•] This study examines the effect of a cognitive task on dyslexic children's postural control. [•] Automatic integration of visual inputs and postural control is deficient in dyslexic children. [•] Focus attention on the secondary cognitive task leads to an impaired postural stability. [Copyright &y& Elsevier]

Highlights: [•] While reading a text the saccade amplitude is similar for patients with vergence insufficiency compared to controls children. [•] Also, the duration of the fixations is the same for both groups of children. [•] However patients show poor binocular coordination during and after the saccades. [•] After oculomotor training therapy, an improvement of the binocular coordination during and after the saccades is found. [ABSTRACT FROM AUTHOR]

Abstract: Vergence insufficiency is frequent in many populations including children with vertigo in the absence of measurable vestibular dysfunction. Orthoptic exercises are typically used to improve vergence and the clinical practice suggests that simple repetition of vergence movements improves it. Objective eye movement recordings were used to asses the dynamics and spatial–temporal properties of convergence (8.7°) and divergence (2.7°) along the midline while these movements were repeated 80 times. Eight children, aged on average 13years and showing vertigo symptoms accompanied with vergence insufficiency, participated. For both, convergence and divergence the velocity increased and the overall duration decreased; the amplitude of the mean transient component of the response changed significantly. These findings are compatible with models of double mode control of vergence eye movements (transient – open-loop vs. sustained – closed loop). Due to simple repetitions a real improvement in the dynamics of vergence along the midline occurred. [Copyright &y& Elsevier]

Abstract: The purpose of the study was to examine spatio-temporal characteristics of horizontal eye movements in the natural space (saccade, vergence and combined movements) in young subjects with early onset convergent or divergent strabismus. Nine young subjects (8–20 years old) were tested: three with divergent strabismus, six with convergent strabismus. A standard paradigm was used to elicit pure horizontal saccades at far and at close viewing distance, pure vergence along the median plane (convergence and divergence) and saccades combined with vergence movements. Horizontal eye movements from both eyes were recorded by a photoelectric device. Eye movements were recorded before surgery, and, for the majority of the subjects, two times after surgery. Before surgery the accuracy of convergence and divergence movements in their pure or combined form was poor with respect to normal values. The mean velocity of convergence was also abnormally slow. Strabismus surgery improved significantly the accuracy of these types of eye movements. The speed of pure convergence and of divergence combined movements increased significantly after surgery. We concluded that poor vergence eye movement’s performance, particularly those found for convergence in strabismic subjects could be due to impairment in the central structures related to sensory disparity inputs. Adaptive mechanisms promoted by the realignment of the eyes could be at the origin of the improvement in the vergence performances observed in our subjects after strabismus eye surgery. [Copyright &y& Elsevier]

Abstract: The present study examines the quality of binocular coordination of saccades at far and near distance in 15 children with symptoms of vertigo headache and equilibrium disorders; these children show normal vestibular function but abnormal convergence eye movements (e.g., long time preparation, slow execution and poor accuracy, see ). The results show normal binocular saccade coordination at far distance, but large abnormal disconjugacy for saccades at near distance. During combined saccade–vergence movements (studied in six of these children), convergence remains abnormally slow. This supports the interpretation according to which poor binocular yoking of the saccades is linked to the reduced ability to produce fast convergence during the saccade; a learning mechanism based on rapid vergence would help to reduce the abducting–adducting asymmetry of the saccades. An alternative interpretation would be reduced learning ability for monocular adjustment of the saccade signals. [Copyright &y& Elsevier]

Abstract: The goal of this study was to examine latency of horizontal eye movements in the natural space (saccades, vergence, and combined saccade–vergence movements) in children with early onset convergent or divergent strabismus. Ten children were tested (8–11 years old): three with divergent strabismus, seven with convergent strabismus. A paradigm was used to elicit pure lateral saccades at far and near distance, pure vergence (convergence and divergence) and saccades combined with vergence movements. Horizontal eye movements from both eyes were recorded simultaneously by a photoelectric device (Oculometer, Dr. Bouis). The latency of saccades (at far and near distance), of vergence (convergence and divergence), and of combined movements greatly varies among subjects and has tendency to be longer than that observed in normal children of matched age, however, these differences reach significance in only a few cases. Children with divergent strabismus and residual gross binocular vision show abnormally longer vergence latencies than children with convergent strabismus without binocular vision. The initiation of combined movements does not show a dominant pattern, such as preceding vergence, as is found in normal children. Finally, strabismus surgery has no major effect on latencies. We conclude that there is no overall deficiency in latencies of eye movements in 3D space in children with early onset strabismus. Most likely, monocular visual input can be efficient as normal binocular vision for vergence movements. In a few subjects with divergent strabismus and fragile, intermittent binocular vision, latencies can be abnormally long, just because of the fragile binocular input and/or attention effort needs to use it. The absence of a pattern of initiation similar to normal children could be due to attention and fixation capabilities. [Copyright &y& Elsevier]

Abstract: The purpose of the present study was to examine in 7 years old normal children who just learnt to read, saccade and fixation characteristics during reading single words. Eight children were studied and their results were compared to those of eight normal adults doing the same task. For each group word reading data were also compared with data in a task requiring saccades and fixations to target-LEDs. Horizontal saccades from both eyes were recorded with a photoelectric device (Oculometer, Bouis). Latencies of saccades both to words and to LEDs presented at predictable location were similar, and they were also similar between children and adults. In contrast, disconjugacy of saccades was significantly increased for children and similar in the two tasks (LEDs or words). Disconjugate post-saccadic drift and its velocity were also significantly higher in children and similar in the two tasks. Substantial conjugate leftward drift was present for children only, and for the word task only. Finally, fixation duration on words was significantly longer in children than in adults. We conclude that binocular coordination and fixation stability is poor in children and that it could be partially responsible for the long fixation duration. Binocular coordination does not depend on the task (LEDs or words) neither for adults, nor for children; this contrasts prior reports. [Copyright &y& Elsevier]

Le terme dyslexie a été créé en 1887 lorsqu'un ophtalmologiste a décrit la difficulté d'apprendre à lire. Elle affecte entre 5 et 15 % de la population d'âge scolaire. Après un siècle de recherche, nous ne connaissons toujours pas son étiologie. La lecture est un processus cognitif complexe dans lequel interviennent plusieurs mécanismes (perception visuelle, mouvements des yeux et capacités sémantiques et linguistiques). Les chercheurs ont suggéré plusieurs théories de la dyslexie et l'hypothèse d'un déficit phonologique de la dyslexie a été partagée par plusieurs auteurs. Des études d'imagerie récentes ont montré que les déficiences phonologiques chez les dyslexiques sont corrélées à des anomalies importantes de la structure corticale de l'hémisphère gauche. Pris ensemble, ces résultats suggèrent que la théorie phonologique est partiellement correcte, mais qu'elle ne peut pas expliquer toutes les déficiences observées dans la dyslexie. Chez les enfants dyslexiques, nous observons des patterns oculomoteurs anormaux lors de la lecture : saccades fréquentes de faible amplitude, fixations longues, nombreuses saccades à gauche (rétro-saccades) et un mauvaise contrôle binoculaire pendant et après les saccades. Ces résultats suggèrent un déficit de traitement de l'information visuelle ainsi qu'une immaturité d'interaction entre les systèmes saccade et vergence. Nous aborderons d'abord, quelques types de rééducation visuelle, testée par notre équipe, susceptibles d'améliorer les performances de lecture chez les enfants dyslexiques. Dans la deuxième partie de la présentation nous présenterons quelques études récentes sur la qualité du contrôle postural des enfants dyslexiques. Dans l'ensemble, toutes ces études suggèrent un déficit au niveau du cervelet. L'intégration cérébelleuse qui est susceptible de s'améliorer par l'entraînement pourrait représenter une opportunité thérapeutique pour la rééducation de la dyslexie. [ABSTRACT FROM AUTHOR]

The objective was to explore how face exploration affects postural control in healthy children. The novelty here is that eye movements and posture were simultaneously recorded. Three groups of children participated in the study: 12 children of 7.8 ± 0.5 years old, 13 children of 10.4 ± 0.5 years old and 12 children of 15.7 ± 0.9 years old. Eye movements were recorded by video-oculography and postural stability was recorded by a platform. Children were invited to explore five emotional faces (neutral, happy, sad fear and angry). Analysis of eye movements was done on saccadic latency, percentage of exploration time spent and number of saccades for each specific region of interest (ROI): eyes, nose and mouth. Analysis of posture was made on surface area, sway length and mean velocity of the center of pressures (CoP). Results showed that visual strategies, exploration and postural control develop during childhood and adolescence. Indeed, after nine years-old, children started to look the eyes ROI firstly, then the nose ROI and finally the mouth ROI. The number of saccades decreased with the age of children. The percentage of exploration time spent in eyes ROI was longer than the others ROIs and greater for unpleasant faces (sad, fear and angry) with respect to pleasant emotional face (happy). We found that in front of sad and happy faces the surface area of the CoP was significantly larger compared to other faces (neutral and angry). These results suggest that visual strategies and postural control change during children's development and can be influenced by the emotional face. [ABSTRACT FROM AUTHOR]

Aim: The aim of the present study was to examine the effects of colored filters on reading performance and eye movement control in children with and without dyslexia.Methods: Eighteen children with dyslexia and 18 children without dyslexia were seated on a chair with their heads stabilized by a forehead and chin support. The children read different texts under the following three filter conditions: no filter, yellow filter, and green filter. The children's eye movements were recorded with a Mobile EyeBrain Tracker. Reading total time, duration of fixation between two successive saccades, pro-saccades amplitude and number of pro- and retro-saccades were obtained.Results: Children with dyslexia read the fastest and had the shortest fixation time in the green filter condition compared with the other conditions. Furthermore, children with dyslexia showed the shortest fixation time in the green filter condition with respect to the other conditions.Conclusions: Taken together, these results suggested that the green filter improved reading performance in children with dyslexia because the filter most likely facilitated cortical activity and decreased visual distortions. [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore the possible change in eye movement performance in a group of dyslexic and non-dyslexic children reading four lines of a text with different font sizes and spaces between the words. Fifteen dyslexic children from 7 to 12 years old and two groups of fifteen non-dyslexic children, respectively reading and chronological age-matched group, participated in this study. Horizontal eye movements from both eyes were recorded by a video-system (EyeBrain T2®) while the children were reading a text. Three different texts were used with different font sizes and spaces between words. Results showed that increasing font size and character spacing significantly reduced duration of the fixation and increased the number and amplitude of prosaccades in all groups of children tested. Interestingly, while reading texts in which the letters were larger and more spaced (Texts 2 and 3), the duration of fixations in dyslexic and in non-dyslexic children groups decreased, becoming similar to those reported in the non-dyslexic children group. We suggest that large letter spacing between words could be employed in schools to help dyslexic children in order to ameliorate their reading performance. [ABSTRACT FROM AUTHOR]

Highlights • Dyslexic children need longer eye fixation in reading a text impairing reading performance. • Reading time and eye fixation are similar for both non- and dyslexic children in the Landolt task. • Dyslexic children postural performance is worse for both visual tasks but more in the Landolt task. • Postural performance in dyslexic children is not related to lexical and semantic requirements. Abstract In this study, we investigated the eye movement and postural control performance in dyslexic children while reading text and performing Landolt reading when sitting and standing. Fifteen dyslexic and 15 non-dyslexic children were asked to sit in a chair while the eye movements were recorded, and were then asked to stand on an unstable platform while eye movements and postural sway were recorded simultaneously at the time of Landolt reading and text reading. Eye movements were recorded binocularly by Mobile EyeBrain Tracker (MobileT2®, SuriCog) and center of pressure excursions were recorded by Multitest Equilibre (by Framiral®). The dependent variables for visual performance in the reading tasks were: total reading time, mean duration of fixation, number of pro- and retro-saccades, and amplitude of pro-saccades. The dependent variable for postural performance was the center of pressure area. The results showed that dyslexic children spent more time reading the text compared to non-dyslexic children (p < 0.02). However, no difference was observed for the Landolt reading task (p > 0.05). Dyslexic children performed longer fixations in the sitting condition as compared to the standing (p < 0.03), namely, higher number of pro- (p < 0.001) and retro- saccades (p < 0.001), and smaller pro-saccades amplitude (p < 0.001). Therefore, when the linguistic and semantic requirements are not involved in the reading task, dyslexic children perform similar to non-dyslexic children even in different task requirements (p > 0.05). Finally, postural performance was poorer in dyslexic children than in non-dyslexic children in both the reading tasks (p < 0.02). However, postural control performance, which was poor in dyslexic children, is not related to lexical and semantic reading requirements. [ABSTRACT FROM AUTHOR]

Purpose The objective of this study was to explore vertical binocular coordination in dyslexic and non-dyslexic children during saccades and post-saccadic fixation period while reading a text. Methods Binocular eye movements were recorded by an infrared system (Mobile T2 ® , SuriCog) in thirty-six dyslexic children from 7.3 to 13.6 years of age (mean age: 10.4 ± 0.3 years) who were asked to silently read a four-line text during binocular viewing. Data were compared to those of thirty-six age-matched non-dyslexic children. Results Vertical disconjugacy during post-saccadic fixation was higher in dyslexic children with respect to non-dyslexic children group. Vertical disconjugacy was not age-dependent either for dyslexic children or for non-dyslexic children. Conclusions The poor binocular vertical coordination observed in dyslexic children while reading could suggest a deficiency in the cerebellum and/or extra-ocular muscles involved in vertical eye alignment. Moreover, the fact that this vertical binocular coordination was not age-dependent could be due to an abnormal eye position and/or to a dysfunction of midbrain structures involved in vertical vergences. [ABSTRACT FROM AUTHOR]

Dyslexic children show impaired in postural stability. The aim of our study was to test the influence of foot soles and visual information on the postural control of dyslexic children, compared to non-dyslexic children. Postural stability was evaluated with TechnoConcept® platform in twenty-four dyslexic children (mean age: 9.3±0.29years) and in twenty-four non-dyslexic children, gender- and age-matched, in two postural conditions (with and without foam: a 4-mm foam was put under their feet or not) and in two visual conditions (eyes open and eyes closed). We measured the surface area, the length and the mean velocity of the center of pressure (CoP). Moreover, we calculated the Romberg Quotient (RQ). Our results showed that the surface area, length and mean velocity of the CoP were significantly greater in the dyslexic children compared to the non-dyslexic children, particularly with foam and eyes closed. Furthermore, the RQ was significantly smaller in the dyslexic children and significantly greater without foam than with foam. All these findings suggest that dyslexic children are not able to compensate with other available inputs when sensorial inputs are less informative (with foam, or eyes closed), which results in poor postural stability. We suggest that the impairment of the cerebellar integration of all the sensorial inputs is responsible for the postural deficits observed in dyslexic children. [ABSTRACT FROM AUTHOR]

Objective The first goal of the present study is to analyze the postural control in strabismic children in four different visual conditions (eyes open, eyes closed and monocular viewing with squint eye and non-squint eye). Secondly, we wish to explore the effect of strabismus surgery in postural control. Method Postural stability was recorded with a platform (TechnoConcept ® ) in 23 strabismic children aged from 4.4 to 14.8 years old (mean age: 8.4 years); 12 of these children were also examined at least two months after strabismus surgery. We analyzed the surface, the length, and the mean speed of the Center of Pressure displacement (CdP), and we calculated the Romberg’s Quotient (that is for each postural parameter the ratio between eyes closed relative to eyes open). Results Strabismic children are significantly more stable when they can use their visual information to control their posture. Also, postural stability was better when the non-squint eye was viewing. For the first time, we observed the important role of vision (by calculating Romberg’s Quotient) in strabismic children with binocular vision in comparison of strabismic children without binocular vision. Finally, we found that eye surgery improves postural stability. Conclusion Strabismic children use visual inputs to control their posture. Moreover, binocular vision plays an important role in postural control. Strabismus surgery improves postural stability. Significance Visual inputs from the non-squint eye and binocular vision are important to control stability. [ABSTRACT FROM AUTHOR]

Objective The aim of this study is to examine postural control of dyslexic children using both spatial and temporal analysis. Methods Thirty dyslexic (mean age 9.7 ± 0.3 years) and thirty non-dyslexic age-matched children participated in the study. Postural stability was evaluated using Multitest Equilibre from Framiral®. Posture was recorded in the following conditions: eyes open fixating a target (EO) and eyes closed (EC) on stable (-S-) and unstable (-U-) platforms. Results The findings of this study showed poor postural stability in dyslexic children with respect to the non-dyslexic children group, as demonstrated by both spatial and temporal analysis. In both groups of children postural control depends on the condition, and improves when the eyes are open on a stable platform. Dyslexic children have spectral power indices that are higher than in non-dyslexic children and they showed a shorter cancelling time. Conclusion Poor postural control in dyslexic children could be due to a deficit in using sensory information most likely caused by impairment in cerebellar activity. Significance The reliability of brain activation patterns, namely in using sensory input and cerebellar activity may explain the deficit in postural control in dyslexic children. [ABSTRACT FROM AUTHOR]

Vertical saccades have never been studied in dyslexic children. We examined vertical visually guided saccades in fifty-six dyslexic children (mean age: 10.5 ± 2.56 years old) and fifty-six age matched non dyslexic children (mean age: 10.3 ± 1.74 years old). Binocular eye movements were recorded using an infrared video-oculography system (mobileEBT ® , e(ye)BRAIN). Dyslexic children showed significantly longer latency than the non dyslexic group, also the occurrence of anticipatory and express saccades was more important in dyslexic than in non dyslexic children. The gain and the mean velocity values were significantly smaller in dyslexic than in non dyslexic children. Finally, the up–down asymmetry reported in normal population for the gain and the velocity of vertical saccades was observed in dyslexic children and interestingly, dyslexic children also reported an up–down asymmetry for the mean latency. Taken together all these findings suggested impairment in cortical areas responsible of vertical saccades performance and also at peripheral level of the extra-ocular oblique muscles; moreover, a visuo-attentionnal bias could explain the up–down asymmetry reported for the vertical saccade triggering. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to examine the postural control in children with strabismus before and after eye surgery. Control of posture is a complex multi-sensorial process relying on visual, vestibular and proprioceptive systems. Reduced influence of one of such systems leads to postural adaptation due to a compensation of one of the other systems . Nine children with strabismus (4–8 years old) participated in the study. Ophthalmologic, orthoptic, vestibular and postural tests were done before and twice (2 and 8 weeks) after eye surgery. Postural stability was measured by a platform (TechnoConcept): two components of the optic flux were used for stimulation (contraction and expansion) and two conditions were tested eyes open and eyes closed. The surface area of the center of pressure (CoP), the variance of speed of the CoP and the frequency spectrum of the platform oscillations by fast Fourier transformation were analysed. Before surgery, similar to typically developing children, postural stability was better in the eyes open condition. The frequency analysis revealed that for the low frequency band more energy was spent in the antero-posterior direction compared to the medio-lateral one while the opposite occurred for the middle and the high frequency bands. After surgery, the eye deviation was reduced in all children and their postural stability also improved. However, the energy of the high frequency band in the medio-lateral direction increased significantly. These findings suggest that eye surgery influences somatosensory properties of extra-ocular muscles leading to improvement of postural control and that binocular visual perception could influence the whole body. [Copyright &y& Elsevier]

Introduction Les objectifs de notre étude sont d'étudier l'impact de la dégénérescence maculaire liée à l'âge (DMLA) sur le contrôle postural grâce à une analyse temporelle des oscillations du centre de pression ; puis d'étudier l'impact de la dominance oculaire sur la stabilité posturale des sujets avec DMLA selon différentes conditions visuelles. Nos hypothèses sont que les sujets avec DMLA uni- ou bilatérale présentent des stratégies de compensation posturale différentes, et que les sujets avec DMLA sont plus stables en condition œil dominant ouvert qu'en condition les deux yeux ouverts. Matériels et méthodes La stabilité posturale a été enregistrée avec la plateforme de force Framiral® chez dix sujets avec DMLA unilatérale, dix sujets avec DMLA bilatérale et dix sujets sains du même âge. Sept conditions visuelles ont été testées : fixation d'une cible lumineuse yeux ouverts (YO), œil dominant ouvert (OD), œil non dominant ouvert (OND), yeux fermés (YF) et vision perturbée (VP) par stimuli optocinétiques (VP-YO, VP-OD, VP-OND). Les paramètres évalués sont la surface et la vitesse de déplacement du centre de pression, et l'indice d'instabilité posturale (IIP). Résultats L'IIP est majoré chez les sujets atteints de DMLA unilatérale et bilatérale. Les sujets avec DMLA unilatérale sont plus stables en condition VP-OD qu'en condition VP-YO. Les sujets sains en condition YF sont plus stables que les sujets avec DMLA. Conclusion Nos données suggèrent que les sujets avec DMLA bilatérale présentent des stratégies de compensation posturale différentes des sujets avec DMLA unilatérale. D'autres études sont nécessaires pour affiner ces résultats et développer des techniques de rééducation. [ABSTRACT FROM AUTHOR]