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.

Use of monocular and binocular visual cues for postural control in children.

The purpose of the present study was to examine how children's postural control is affected by different visual cues. Sixteen children, ages 8 and 12 years, and eight adults participated in the study. Each was asked to stand upright inside a moving room, which oscillated at 0.2 Hz, while facing the frontal wall at two distances: 75 and 150 cm, under monocular and binocular vision conditions. Vision manipulation induced corresponding body sway in all participants, but vision effect was the smallest in the monocular vision condition, at the greater distance (150 cm) from the front wall. More importantly, however, the influence of visual manipulation on body sway was age-dependent, with the younger children showing less visually induced body sway than the older children and adults. This aging effect was more dramatic in the monocular vision condition. These results suggest that development of the visual system is not fully completed until the age of 12 years and that eye movement and binocular vision might play an important role in how visual cues are coupled to body sway.

Eye movements and postural control in dyslexic children performing different visual tasks.

The aim of this study was to examine eye movements and postural control performance among dyslexic children while reading a text and performing the Landolt reading task. Fifteen dyslexic and 15 non-dyslexic children were asked to stand upright while performing two experimental visual tasks: text reading and Landolt reading. In the text reading task, children were asked to silently read a text displayed on a monitor, while in the Landolt reading task, the letters in the text were replaced by closed circles and Landolt rings, and children were asked to scan each circle/ring in a reading-like fashion, from left to right, and to count the number of Landolt rings. Eye movements (Mobile T2®, SuriCog) and center of pressure excursions (Framiral®, Grasse, France) were recorded. Visual performance variables were total reading time, mean duration of fixation, number of pro- and retro-saccades, and amplitude of pro-saccades. Postural performance variable was the center of pressure area. The results showed that dyslexic children spent more time reading the text and had a longer duration of fixation than non-dyslexic children. However, no difference was observed between dyslexic and non-dyslexic children in the Landolt reading task. Dyslexic children performed a higher number of pro- and retro-saccades than non-dyslexic children in both text reading and Landolt reading tasks. Dyslexic children had smaller pro-saccade amplitude than non-dyslexic children in the text reading task. Finally, postural performance was poorer in dyslexic children than in non-dyslexic children. Reading difficulties in dyslexic children are related to eye movement strategies required to scan and obtain lexical and semantic meaning. However, postural control performance, which was poor in dyslexic children, is not related to lexical and semantic reading requirements and might not also be related to different eye movement behavior.

Eye movement and postural sway in dyslexic children during sitting and standing.

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.

Effect of colored filters on reading capabilities in dyslexic children.

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.

The Effect of Dual Task on Attentional Performance in Children With ADHD.

Attention-deficit/hyperactivity disorder (ADHD) is a common psychiatric disorder without validated objective markers. Oculomotor behavior and executive motor control could potentially be used to investigate attention disorders. The aim of this study was to explore an oculomotor and postural dual task in children with ADHD. Forty-two children were included in the study, gathering children with ADHD (n = 21) (mean 8.15 age ± years 0.36) and sex-, age-, and IQ-matched typically developing children (TD). Children performed two distinct fixation tasks in three different postural conditions. Eye movements and postural body sway were recorded simultaneously, using an eye tracker and a force platform. Results showed that children with ADHD had poor fixation capability and poor postural stability when compared to TD children. Both groups showed less postural control on the unstable platform and displayed more saccades during the fixation task. Surprisingly, in the dual unstable platform/fixation with distractor task, the instability of children with ADHD was similar to that observed in TD children. "Top-down" dys-regulation mediated by frontal-striatal dysfunction could be at the origin of both poor inhibitory oculomotor deficits and impaired body stability reported in children with ADHD. Finally, we could assume that the fact both groups of children focused their attention on a secondary task led to poor postural control. In the future it could be interesting to explore further this issue by developing new dual tasks in a more ecological situation in order to gain more insight on attentional processes in children with ADHD. HIGHLIGHTS - Children with ADHD showed poor fixation capability when compared to TD children. - "Top-down" dys-regulation mediated by frontal-striatal dysfunction could be at the origin of both poor inhibitory oculomotor deficits and impaired body stability reported in children with ADHD. - Both groups of children focused their attention on the visual fixation task leading to poor postural control. - In the future it could be interesting to develop new dual tasks in an ecological situation in order to gain more insight on attentional processes in children with ADHD.

Associação entre marcadores inflamatórios e o padrão locomotor durante a ultrapassagem de obstáculos em idosos / Association between inflammatory markers and locomotor pattern during obstacle avoidance in older adults

Resumo Objetivo investigar a associação dos biomarcadores inflamatórios na tarefa de ultrapassagem de obstáculos com diferentes níveis de complexidade manipulados pela característica do obstáculo (sólido e frágil) em idosos. Método 17 idosos (≥60 anos) foram avaliados em dois momentos: 1) Análise do padrão locomotor durante a ultrapassagem de obstáculo em duas condições (sólido e frágil). As variáveis estudadas, para membros de abordagem e suporte foram: velocidade, comprimento, largura e duração da passada, distância horizontal pé-obstáculo, distância horizontal obstáculo-pé, distância vertical pé-obstáculo e Máxima elevação do pé. 2) A análise dos biomarcadores interleucina 6 (IL-6) e proteína C Reativa (PCR) foi realizada por meio de coleta de sanguínea. A análise de regressão linear múltipla foi realizada para verificar associação entre o padrão locomotor e os biomarcadores inflamatórios (IL-6 e PCR) com nível de significância de p≤0,05. Resultados A análise de regressão mostrou que a Interleucina 6 apresentou associação com as seguintes variáveis: 1) largura da passada na condição obstáculo sólido, 2) máxima elevação do pé (membro de suporte) para ultrapassagem do obstáculo frágil, 3) distância horizontal pé-obstáculo (membro de abordagem) na condição de obstáculo sólido, 4) máxima elevação do pé (membro de abordagem) para ultrapassagem do obstáculo frágil, 5) máxima elevação do pé (membro de abordagem) para ultrapassagem do obstáculo sólido. A PCR apresentou associação com a variável Distância Horizontal Pé-Obstáculo (membro de abordagem) apenas para a condição de obstáculo frágil. Conclusão Os biomarcadores inflamatórios apresentam uma associação com o comportamento locomotor em idosos, independente da condição de fragilidade do obstáculo.

Abstract Objective to investigate the association of inflammatory biomarkers on the locomotor pattern during obstacle avoidance with different levels of complexity manipulated by the characteristic of the obstacle (solid and fragile) in older adults. Method 17 older adults (≥60 years old) were evaluated in two moments: 1) Analysis of the locomotor pattern during obstacle crossing in two conditions (solid and fragile). The variables studied for trailing and leading limbs were: speed, length, width and duration of the stride, horizontal foot-obstacle distance, horizontal obstacle-foot distance, vertical foot-obstacle distance and Maximum foot elevation. 2) Blood collection, for analysis of the inflammatory biomarkers Interleukin 6 (IL6) and C-Reactive Protein (CRP). Multiple linear regression analysis was performed to verify association between locomotor pattern and inflammatory biomarkers (IL6 and CRP) with a significance level of p≤0.05. Results The regression analysis showed that Interleukin 6 was associated with the following variables: 1) stride width in the solid obstacle condition, 2) maximum foot elevation (leading limb) to avoidance the fragile obstacle, 3) horizontal foot-obstacle distance (trailing limb) in solid obstacle condition, 4) maximum foot elevation (trailing limb) to avoidance the fragile obstacle, 5) maximum foot elevation (trailing limb) to avoidance the solid obstacle. C-Reactive Protein was associated with the horizontal foot-obstacle distance (trailing limb) only for the fragile obstacle condition. Conclusion Inflammatory biomarkers are associated with the locomotor pattern in older adults, regardless of the fragility of the obstacle.

Postural control performance of active and inactive older adults assessed through postural tasks with different levels of difficulty

Abstract Aim: To investigate postural control between active (AOA) and inactive (IOA) older adults and active young adults (YA) due to the difficulty level of the postural task. Methods: 25 active YA, 31 AOA, and 30 IOA were invited to perform postural tasks with eyes open and closed: bipedal stance on a rigid surface, bipedal stance on an unstable surface, semi-tandem stance on a rigid surface, and semi-tandem stance on an unstable surface. Results: IOA (0.74 cm) presented higher COP displacement amplitude in the mediolateral direction than AOA (0.64 cm) only in bipedal stance on an unstable surface with eyes closed condition (p ≤ 0.0001). In relation to frequency variables, IOA (0.37 Hz) presented a greater frequency band with 50% of the spectral power in the mediolateral direction than AOA (0.28 Hz) in all experimental conditions, except for semi-tandem stance on a rigid surface (p ≤ .0001). AOA (0.62 cm - 0.28 Hz) and IOA (0.67 cm - 0.37 Hz) presented an increase in time/frequency variables in both directions (anterior-posterior and mediolateral) than YA (0.52 cm - 0.17 Hz) (p ≤ 0.0001) that indicates a worse performance of postural control as the level of task difficulty increased, such as unstable base with eyes open and closed. Conclusion: Older adults tend to present greater COP sway and velocity when subjected to complex tasks compared with younger, which is more evident in older adults physically inactive. This could be considered an adaptive strategy by older adults to minimize the risk of losing balance and, consequently, falling.

Analysis of postural control and muscle function performance of older adults participating in a multicomponent exercise program in primary health care / Análise do desempenho do controle postural e da função muscular de idosos participantes de um programa de exercício multicomponente na Atenção Primária à Saúde

Objectives: This cross-sectional study aimed to investigate (1) postural control performance in different postural tasks and (2) muscle strength and power of the hip, knee, and ankle of active vs inactive older adults. Methods: The sample consisted of 61 healthy community-dwelling older adults, classified into 2 groups: active, consisting of participants of a multicomponent exercise program offered through the Exercise Orientation Service; and inactive. Participants were considered physically active/inactive in the past 3 months. Postural control was assessed using a force plate in 8 postural tasks. Muscle function was evaluated using an isokinetic dynamometer. T-tests were used to compare clinical characteristics between the groups. ANCOVA and MANCOVA were used to compare differences in variables of postural control and muscle function. Results: Active participants had higher levels of physical activity, clinical balance, and quality of life than inactive participants. The active group had lower values for area (center of pressure) than the inactive group under the following conditions: bipedal stance on an unstable surface with eyes open and with eyes closed, and semi-tandem stance on an unstable surface with eyes open. The active group showed greater muscle power, with higher mean power values for hip abduction and adduction, knee extension, and knee flexion and shorter time to peak torque for hip adduction and ankle dorsiflexion than the inactive group. Conclusions: Multicomponent exercise programs delivered in primary health care settings contributed to improving postural control and muscle power in this sample of older adults, which can potentially help prevent falls and improve quality of life.

Objetivo: Este estudo transversal visou investigar: (1) o desempenho no controle postural em diferentes tarefas e (2) a força e a potência musculares de quadril, joelho e tornozelo de idosos ativos vs. inativos. Metodologia: A amostra foi composta de 61 idosos comunitários saudáveis, classificados em dois grupos: os ativos, participantes do programa de exercício multicomponente ofertado pelo Serviço de Orientação ao Exercício, e os inativos. Os participantes foram considerados fisicamente ativos/inativos nos três meses anteriores. O controle postural foi avaliado em oito tarefas usando-se uma plataforma de força. A função muscular foi mensurada com um dinamômetro isocinético. Foram utilizados testes t para comparar as características clínicas entre os grupos. Análise de covariância e análise multivariada de covariância foram utilizadas para comparar diferenças nas variáveis de controle postural e função muscular. Resultados: Os participantes ativos apresentaram maiores níveis de atividade física, equilíbrio e qualidade de vida que os inativos. O grupo ativo apresentou menores valores de área (centro de pressão) que o inativo nas seguintes condições: base bipodal em superfície instável com olhos abertos e fechados e base semitandem em superfície instável com olhos abertos. O grupo ativo apresentou maior potência que o inativo, com maior valor de potência média para abdução e adução de quadril, extensão e flexão de joelho, e menor tempo de pico de torque para adução de quadril e dorsiflexão de tornozelo. Conclusão: Programas de exercício multicomponente ofertados na Atenção Primária à Saúde contribuíram para melhorar o controle postural e a potência muscular nesta a

Quality of Visual Cue Affects Visual Reweighting in Quiet Standing.

Sensory reweighting is a characteristic of postural control functioning adopted to accommodate environmental changes. The use of mono or binocular cues induces visual reduction/increment of moving room influences on postural sway, suggesting a visual reweighting due to the quality of available sensory cues. Because in our previous study visual conditions were set before each trial, participants could adjust the weight of the different sensory systems in an anticipatory manner based upon the reduction in quality of the visual information. Nevertheless, in daily situations this adjustment is a dynamical process and occurs during ongoing movement. The purpose of this study was to examine the effect of visual transitions in the coupling between visual information and body sway in two different distances from the front wall of a moving room. Eleven young adults stood upright inside of a moving room in two distances (75 and 150 cm) wearing a liquid crystal lenses goggles, which allow individual lenses transition from opaque to transparent and vice-versa. Participants stood still during five minutes for each trial and the lenses status changed every one minute (no vision to binocular vision, no vision to monocular vision, binocular vision to monocular vision, and vice-versa). Results showed that farther distance and monocular vision reduced the effect of visual manipulation on postural sway. The effect of visual transition was condition dependent, with a stronger effect when transitions involved binocular vision than monocular vision. Based upon these results, we conclude that the increased distance from the front wall of the room reduced the effect of visual manipulation on postural sway and that sensory reweighting is stimulus quality dependent, with binocular vision producing a much stronger down/up-weighting than monocular vision.

Dyslexic children suffer from less informative visual cues to control posture.

The goal of this study was to investigate the effects of manipulation of the characteristics of visual stimulus on postural control in dyslexic children. A total of 18 dyslexic and 18 non-dyslexic children stood upright inside a moving room, as still as possible, and looked at a target at different conditions of distance between the participant and a moving room frontal wall (25-150 cm) and vision (full and central). The first trial was performed without vision (baseline). Then four trials were performed in which the room remained stationary and eight trials with the room moving, lasting 60s each. Mean sway amplitude, coherence, relative phase, and angular deviation were calculated. The results revealed that dyslexic children swayed with larger magnitude in both stationary and moving conditions. When the room remained stationary, all children showed larger body sway magnitude at 150 cm distance. Dyslexic children showed larger body sway magnitude in central compared to full vision condition. In the moving condition, body sway magnitude was similar between dyslexic and non-dyslexic children but the coupling between visual information and body sway was weaker in dyslexic children. Moreover, in the absence of peripheral visual cues, induced body sway in dyslexic children was temporally delayed regarding visual stimulus. Taken together, these results indicate that poor postural control performance in dyslexic children is related to how sensory information is acquired from the environment and used to produce postural responses. In conditions in which sensory cues are less informative, dyslexic children take longer to process sensory stimuli in order to obtain precise information, which leads to performance deterioration.

Sensorimotor integration in dyslexic children under different sensory stimulations.

Dyslexic children, besides difficulties in mastering literacy, also show poor postural control that might be related to how sensory cues coming from different sensory channels are integrated into proper motor activity. Therefore, the aim of this study was to examine the relationship between sensory information and body sway, with visual and somatosensory information manipulated independent and concurrently, in dyslexic children. Thirty dyslexic and 30 non-dyslexic children were asked to stand as still as possible inside of a moving room either with eyes closed or open and either lightly touching a moveable surface or not for 60 seconds under five experimental conditions: (1) no vision and no touch; (2) moving room; (3) moving bar; (4) moving room and stationary touch; and (5) stationary room and moving bar. Body sway magnitude and the relationship between room/bar movement and body sway were examined. Results showed that dyslexic children swayed more than non-dyslexic children in all sensory condition. Moreover, in those trials with conflicting vision and touch manipulation, dyslexic children swayed less coherent with the stimulus manipulation compared to non-dyslexic children. Finally, dyslexic children showed higher body sway variability and applied higher force while touching the bar compared to non-dyslexic children. Based upon these results, we can suggest that dyslexic children are able to use visual and somatosensory information to control their posture and use the same underlying neural control processes as non-dyslexic children. However, dyslexic children show poorer performance and more variability while relating visual and somatosensory information and motor action even during a task that does not require an active cognitive and motor involvement. Further, in sensory conflict conditions, dyslexic children showed less coherent and more variable body sway. These results suggest that dyslexic children have difficulties in multisensory integration because they may suffer from integrating sensory cues coming from multiple sources.

Controle postural e informação somatosensorial em idosos diabéticos praticantes e não praticantes de atividade física / Postural control and somatosensory information in diabetic elderlies physically active and non-active

O objetivo deste estudo foi avaliar o desempenho do controle postural e a obtenção de informação somatosensorial de idosos diabéticos praticantes e não praticantes de atividade física. Participaram deste estudo dez idosos diabéticos ativos (62±4,4 anos) (GDA), dez diabéticos sedentários (65,5±7,4 anos) (GDS) e dez idosos sadios ativos (63,2±4,5anos) (GCA), que realizaram avaliação de sensibilidade cutânea e detecção de movimento passivo, nas articulações do tornozelo e joelho, e de manutenção da postura nas posturas bipedal e tandem stance. Os resultados indicaram pior desempenho do GDS na detecção do movimento passivo e do controle postural, nas condições de maior exigência das tarefas. Especificamente, o GDS apresentou maior amplitude média de oscilação, na direção médio-lateral, durante manutenção da postura ereta na posição tandem stance. No teste de sensibilidade ao movimento passivo, o GDS precisou de um maior deslocamento angular para perceber o movimento das articulações do joelho e tornozelo. Nenhuma diferença foi observada entre os GDA e GCA. Estes resultados indicam que as alterações decorrentes do diabetes deterioram a capacidade de obtenção de informação sensorial e funcionamento do sistema de controle postural. Entretanto, essas alterações podem ser minimizadas com a prática regular de atividade física, fazendo com que pacientes diabéticos ativos apresentem o mesmo desempenho que idosos ativos não diabéticos.

The purpose of this study was to assess the performance of the sensory and postural control somatosensory information in elderly diabetics practitioners and non-practitioners of physical activity programs. Participated of this study ten active diabetics (62±4.4 year-old) (GAD), ten sendentary diabetics (65.5±4.5 year-old) (GSD), and ten healthy elderlies (63.2±4.5 year-old) (GHE), who were submitted to skin sensitivity and passive motion detection tests, in the ankle and knee joints, and maintenance of upright bipodal and tandem stance position. The results indicate worst performance of the GDS in the assessment of passive movement detection and postural control, in the more demanding tasks. Specifically, the GSD showed higher mean sway amplitude, in the medial-lateral direction in the tandem stance position. In the passive motion detection test, the GSD needed a larger angular displacement in order to detect the passive motion of the knee and ankle passive motion. No differences were observed between GAD and GHE. These results indicate that the changes due to diabetes decrease the capacity of obtaining sensory information and the functioning of the postural control system. However, these changes can be minimized with regular physical activity.

Efeitos da manipulação do estímulo visual e da intenção na oscilação postural de idosos / Effects of visual stimulus manipulation and of intention on postural oscillation of elderly women

: Este estudo investigou a influência de características do estímulo visual e o efeito da intenção nas respostas do controle postural frente à manipulação visual de adultas idosas. As 20 participantes permaneceram em pé em uma sala móvel durante sete tentativas com duração de 1 minuto cada, olhando para um alvo fixo, medindo-se sua oscilação corporal. Na primeira tentativa não houve qualquer movimento da sala, porém a partir da segunda a sala foi movimentada no sentido ântero-posterior. Para dez participantes, a velocidade de pico da movimentação foi de 0,6 cm/s e, para as demais, de 1,0 cm/s. A partir da quinta tentativa, as participantes foram informadas do movimento da sala e orientadas a resistir à movimentação. Os resultados indicam que a oscilação corporal das idosas é induzida pelo movimento da sala móvel. Intenção e alteração da característica do estímulo visual reduzem a influência da informação visual na oscilação corporal, mas a manipulação de propriedade do estímulo (neste caso, velocidade), é menos efetiva que a intenção. Essa maior dependência da intenção para alterar a influência de um estímulo sensorial no controle postural indica que o funcionamento do sistema de controle postural em idosos não possibilita ajustes “automáticos” de respostas posturais frente a pequenas variações das condições ambientais. Iinformações sobre tais variações podem ser direcionadas de forma a compensar essa diferença...

This study examined the influence of both visual stimulus features and intention on postural control responses due to visual manipulation of elderly women. Twenty participants stood upright inside a moving room, for seven trials for 1 min apiece, staring at a fixed target, their body sway being measured. The room was not moved during the first trial, but from the second trial on, it was continuously oscillated back and forward. For ten participants, the moving room oscillated with peak velocity of 0.6 cm/s and for the others, with peak velocity of 1.0 cm/s. From the fifth trial on, participants were informed about the movement of the room and instructed to resist to its influence. Results show that body sway is induced by visual manipulation in elderly adults. Intention and change in visual stimulus lead to less influence of the visual information on body sway, but changes in the stimulus properties (velocity, for that matter), is less effective than intention. This higher dependency on intention for changing sensory influence on postural control suggests that postural control in elderly adults does not benefit from “automatic” postural responses due to small environmental changes. Tips and information about such kind of environmental changes should be used in order to make up for such difference in automatic adjustments observed in the elderly...