Dyslexic children need more robust information to resolve conflicting sensory situations

Abstract

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

Specific Learning Disorder in Children and Adolescents, a Scoping Review on Motor Impairments and Their Potential Impacts

“…Then, the three types of SLD are presented: dyslexia (SWRD, SRCD), dyscalculia (SMLD) and dysorthographia (SWED). Each of these sections presented three movement categories (fine, gross and postural skills), assessed by different quantitative and qualitative motor tests [ 69 ], such as the first [ 70 ] and second edition [ 71 ] of the Test of Gross Motor Development (TGMD) [ 11 , 12 , 44 ], the first [ 6 ] and second editions of the Bruininks–Oseretsky Test of Motor (BOT) [ 38 , 56 , 72 , 73 ], the first and second version of Movement Assessment Battery for Children (M-ABC) [ 19 , 37 , 43 , 44 , 47 , 48 , 68 ], the Functional Mobility domain from the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT) [ 19 ], Spiral Drawing Test [ 15 ], Beery–Buktenica Developmental Test of Visual–Motor Integration [ 68 ], Leonard Tapping Task [ 45 ], Dysgraphia Scale [ 74 ], battery of clinical cerebellar tests [ 60 , 75 ], quiet standing paradigms [ 46 , 49 , 50 , 51 , 52 , 53 , 54 , 57 , 62 , 67 ], postural stability limits [ 41 ], Sensory Organisation Test [ 40 ], Multitest Equilibre [ 55 , 58 ], TechnoConcept ® platform [ 59 , 61 ], Motor Coordination Test [ 40 ], Chinese Handwriting Assessment Tool [ 63 ], ...…”

“…The design of these paradigms allowed for impairments in various sensory systems (visual, vestibular, proprioception, tactile) to be investigated, as well as multisensory integration for movement and postural control. These inputs are a very important part of movement and postural control and several studies have hypothesized that they could possibly be linked with motor skill impairments in SLDs [ 10 , 46 , 54 , 59 , 67 , 76 , 77 ]. However, to simplify the first screening of motor skills in children and adolescents with SLDs, our scoping review mainly reported results in the eyes-open condition.…”

“…First of all, compared to their peers, dyslexic children and adolescents showed larger postural instabilities during quiet upright standing (static postural control) with eyes open [ 50 , 51 , 52 , 53 , 55 , 58 , 59 , 81 ] in various conditions: fixing an LED placed near to (25 cm) or far from (150 cm) participants, alternating their focus between the far and near LED targets [ 62 ], performing eye movements to follow a target that is displayed on one side of a monitor, then disappears and immediately reappears on the opposite side with a frequency of 0.5 Hz [ 49 ], read a text naturally [ 57 , 61 ], identify the open character (Landolt reading task) [ 57 ], and visually guide horizontal and vertical saccades [ 61 ], in a tandem position (heel-to-toe) [ 50 ], on compliant mats (4-mm foam, 0.02-m-thick or 0.10-m-thick compliant mat) [ 46 , 59 ] on a stable and unstable platform [ 52 , 54 , 58 ] and in moving room. These were conducted while the platform remained stationary or oscillated back and forward at frequencies of 0.2 or 0.5 Hz [ 52 , 53 , 54 ], with or without lightly touching a stationary or moving bar [ 51 , 54 ]. Many variables were sensitive to this motor impairment: larger length, higher trunk accelerations, spectral power indices, body sway magnitude and variability, mean power frequency of the center of pressure (CoP) displacements, length, mean and variance velocity of the CoP displacements, larger standard deviation in the lateral CoP displacements, spatial and temporal postural index, mean velocity of CoP, Romberg Quotient, Wobble (standard deviation of movement for all the three coordinates of 3D space), etc.…”

“…One major finding of the scoping review revealed that about half of the SLD sample evaluated with the M-ABC revealed that participants showed movement dysfunctions (at or below the 15th percentile rank) [ 19 , 48 ]. Children and adolescents with SLDs displayed significant manual dexterity difficulties [ 45 , 48 , 60 , 65 ] as well as clear impairments in balance [ 41 , 48 , 49 , 50 , 54 , 55 , 57 , 58 , 59 , 60 , 61 , 62 , 66 ]. Both manual dexterity and balance were also significant predictors for functional mobility in children and adolescents with SLDs [ 19 ].…”

“…Other groups of scientists have hypothesized that there is a sensorial process disturbance in SLD. For example, children experience difficulties in dynamically reweighting sensory cues, which are overcome when more informative sensory cues are provided [ 54 ], and are not able to compensate with other available inputs when sensorial inputs are less informative (foam or eyes closed) [ 59 ]. Some results indicate that the poor motor performance in SLD children is related to how sensory information is acquired from the environment and used to produce motor responses [ 53 ].…”