Altered Sensory Conditions Research Articles

Urban sensory conditions alter rival interactions and mate choice in urban and forest túngara frogs.

Sexual communication often takes place in networks with multiple competing signalers being simultaneously assessed by mate choosers. Altered sensory conditions, such as noise and light pollution, can affect communication by altering signal production and perception. While evidence of sensory pollution affecting sexual signaling is widespread, few studies assess impacts on sexual signaling during rival interactions as well as mate choice, let alone whether urban and non-urban populations have diverged in their response. Here, we investigate the effects of urban sensory conditions on sexual communication in urban and forest túngara frogs (Engystomops pustulosus). We recorded dyadic vocal rival interactions and assessed mate choice with and without noise and light pollution in the lab. We show that urban sensory conditions can directly impact the intensity of rival interactions, differences between rivals, and mate choice, though changes were often in opposite directions for frogs of urban and forest origins. Moreover, we demonstrate that urban-induced changes in rival interactions can also indirectly affect how females choose between potential mates. Our study reveals origin-dependent direct and indirect effects of noise and light pollution and suggests local adaptation of sexual communication in urban populations.

Interpersonal contact and altered sensory conditions in video consultation – a qualitative interview study in Danish general practice

Objective To explore possible challenges to General Practitioners’ (GPs’) interpersonal contact with patients in video consultations (VCs), and learn how they change their communication strategies to carry out medical work in a setting with altered sensory conditions. Design, setting, subjects The study included 6 GPs from the Copenhagen area, with different levels of experience of VC. The data consist of 6 interviews with GPs, held in 2021-2022. The semi-structured interviews included playback of a recorded VC between each GP and a patient, inspired by the Video-Stimulated Interview technique. Interviews were transcribed and analyzed using Interpretative Phenomenological Analysis (IPA). Results GPs experienced alterations in the sensation of their patients in VCs, and worried about missing something important, including assessing the patient. Generally, GPs felt that interpersonal contact was good enough for the purpose. GPs compensated for altered sensory conditions on video by asking more questions, repeating their advice, and meta-communicating. They used their senses of sight and hearing relatively more in VCs. Compensation also took the form of triage, so that consultations on sensitive topics or with new patients were not selected to take place on video. Conclusion and implications By compensating for altered sensory conditions in VCs, GPs can carry out their medical work sufficiently well and sustain the best possible interpersonal contact. Our findings are useful for establishing ways to maintain good interpersonal contact between GPs and patients in VCs.

Effects of altered sensory feedback on piano performance errors: An exploratory study

Music performance is an intensive sensorimotor task that involves the generation of mental representations of musical information that are actively accessed, maintained, and manipulated according to the demands of the performance. Internal representations and external information interact through feedback and feedforward processes that adjust the musician’s motor behavior to optimize a musical performance. This study aimed to examine the relationship between altered sensory feedback and performance errors. Seventeen experienced pianists aged between 33 and 54 years performed Hanon Exercise N°1 from memory under four different conditions: (1) normal (normal sensory feedback); (2) closed fallboard (altered haptic and auditory feedback); (3) blindfolded (altered visual feedback); and (4) combined (blindfolded and closed fallboard; altered haptic, auditory, and visual feedback). Performance errors were quantified based on a video analysis of the performances. Results indicated that compared with normal performance, participants made significantly more note errors in the blindfolded condition and more bar-adding errors per trial in the closed fallboard condition. The comparison between the normal condition and the three altered sensory feedback conditions revealed the impact of altering sensory feedback in musical performance. These findings are discussed in the context of music learning.

Impact of sensory reweighting strategies on postural control using the sensory organization test in older adults with and without fall risks.

The Sensory Organization Test (SOT), an integral part of computerized dynamic posturography, plays a crucial role in evaluating postural stability under various altered sensory conditions. Despite its importance, there have been noted inconsistencies in the results pertaining to equilibrium and sensory system evaluations. This study aimed to compare four sensory analysis scores and equilibrium indices between older adults with and without fall risks. The study included 34 participants identified as being at risk of falls and 42 control subjects. To categorize individuals between the two groups, we performed area under the receiver operating characteristic curve analyses. This classification was based on scores from the Modified Falls Efficacy Scale (MFES) and the composite scores obtained from the SOT. In addition, we used the Tampa Scale for Kinesiophobia (TSK) as well as the level of disability. The fall risk group demonstrated significantly higher TSK scores (39.39± 15.24 for control group vs. 54.65±10.70 for fall risk group; t=-5.09, p=0.001). The groups demonstrated a significant interaction on the equilibrium index (F=4.59, p=0.03), which was lower in the fall risk group in Condition 6 with a moving surface and surround and eyes open (t=2.29, p=0.01). The fall risk group demonstrated a higher somatosensory score (t=-1.73, p=0.04). The fall risk group had a lower equilibrium index score in Condition six of the SOT, which was useful for identifying deficits in vestibular function to integrate sensory information under challenging conditions for postural adaptation. This strategy suggested that the fall risk group could compensate for their risk of falls by utilizing more effective somatosensory reweighting strategies compared with the control group.

Decreased Theta Power Reflects Disruption in Postural Control Networks of Fragile X Premutation Carriers.

FRM1 premutation carriers exhibit various subtle deficits in balance and stability, prior to the development of the movement disorder Fragile X Associated Tremor/Ataxia Syndrome (FXTAS). Force plate posturography has increasingly been combined with the temporal sensitive imaging methods such as EEG to offer insight into the neural mechanisms which govern postural control. This study investigated cortical theta power during continuous balance and its relationship to balance performance in Fragile X premutation carriers. Eight premutation carriers and 6 controls stood on a force platform under altered sensory and cognitive conditions while postural sway and high-density EEG data were simultaneously recorded. Carriers exhibited greater sway area when sensory input was reduced (p=0.01) and cognitive load was increased (p=0.01), as well as significantly reduced frontal theta power compared to the Control Group. The relationship between theta power and postural control seen in the control group may indicate an increase in error detection caused by reduced visual input and greater discrepancies between expected and actual balance state. While the lower theta power in frontal regions of carriers may indicate a disruption in neural networks underpinning postural control. Such results provide new insight into the neural correlates of balance control in Fragile X premutation carriers.

POSTURAL STABILITY STRATEGIES IN TRANSTIBIAL AMPUTEES DURING QUIET STANDING IN ALTERED SENSORY CONDITIONS WEARING THREE TYPES OF PROSTHETIC FEET

Individuals with transtibial amputation exhibit altered movement strategy to sustain stability during quiet standing due to reduced proprioception on the amputated limb. The aim of this study is to determine the movement strategies in anterior–posterior and medial–lateral directions in predicting the overall postural stability. In this crossover study, postural stability of ten transtibial amputees was assessed using computed posturography while wearing different prosthetic foot types: solid ankle cushion heel (SACH), single axis (SA) and energy storage and return (ESAR). Three stability indices were measured during four conditions: standing with eyes opened and closed, standing on compliant surface and standing with tilted head. From the standard multiple regression analysis, 63% to 99% of the OSI score in all sensory conditions were explained from the MLSI score, while 11% to 56% from the APSI score. The Pearson’s [Formula: see text] indicated significant strong positive relationship between OSI and MLSI [Formula: see text]–[Formula: see text] during all sensory conditions. The APSI score was significantly lower than OSI during eyes-closed and head extended conditions for all prosthetic feet [Formula: see text]. Adjustments in postural stability strategies in transtibial amputees mostly occurred in medial–lateral direction regardless of prosthetic feet types and altered sensory conditions.

Achilles tendon shear wave speed tracks the dynamic modulation of standing balance.

Standing balance performance is often characterized by sway, as measured via fluctuations of the center of pressure (COP) under the feet. For example, COP metrics can effectively delineate changes in balance under altered sensory conditions. However, COP is a global metric of whole‐body dynamics and thus does not necessarily lend insight into the underlying musculotendon control. We have previously shown that shear wave tensiometers can track wave speeds in tendon as a surrogate measure of the load transmitted by the muscle‐tendon unit. The purpose of this study was to investigate whether shear wave metrics have sufficient sensitivity to track subtle variations in Achilles tendon loading that correspond with postural sway. Sixteen healthy young adults (26 ± 5 years) stood for 10 s with their eyes open and closed. We simultaneously recorded COP under the feet and shear wave speed in the right Achilles tendon. We found that Achilles tendon shear wave speed closely tracked (r > 0.95) dynamic fluctuations of the COP in the anteroposterior direction. Achilles tendon wave speed fluctuations significantly increased during standing with eyes closed, mirroring increases in COP fluctuations. These results demonstrate that tendon wave speed can track the subtle variations in Achilles tendon loading that modulate COP in standing. Hence, shear wave tensiometry exhibits the sensitivity to investigate the muscular control of quiet standing, and may also be useful for investigating other fine motor and force steadiness tasks.

Inhibition and decision-processing speed are associated with performance on dynamic posturography in older adults

Changes in cognition due to age have been associated with falls and reduced standing postural control. Sensory integration is one component of postural control that may be influenced by certain aspects of cognitive functioning. This study investigated associations between measures of cognitive function and sensory integration capabilities for healthy young and older adults. Dynamic posturography was performed using the Equitest Sensory Organization Test (SOT) protocol to evaluate sensory integration during standing using sway-referencing of the platform and/or visual scene to alter somatosensory and visual inputs. The Equilibrium Score was used as a measure of sway. Cognitive testing examined aspects of cognitive function that have been associated with falls in older adults. A correlational analysis investigated associations between the cognitive measures and postural sway during the altered sensory conditions of the SOT. For older subjects only, slower decision-processing speed was associated with increased sway during SOT conditions whenever somatosensation was altered. Reduced perceptual inhibition was associated with increased sway whenever somatosensation was intact, and particularly when vision was altered in the presence of somatosensation. Visuospatial construct ability was associated with sway only when the eyes were closed during altered somatosensation. Task-switching was associated with sway only when vision and somatosensation were intact. With increased age, deficits in decision speed and inhibition appear associated with the sensory integration crucial for balance maintenance. Associations are modulated by the availability of somatosensation and vision. These associations define situations and individual differences in aspects of cognition that may relate to situational loss of balance in older adults.

The Effects of Haemophilia on the Postural Control of Adolescents

A small number of studies have reported that children and adults with haemophilia have impaired balance control and show faster body sway during upright stance than healthy individuals. A decrease of somatosensory information due to multiple bleedings has been suggested to explain this difference. Therefore, the objective of this study was to examine if haemophilia is related to a decreased balance control under altered visual and proprioceptive conditions in male adolescents. Postural sway of healthy (n = 12, Age = 14.8 ± 1.4 years; BMI = 19.8 ± 1.8 kg/m2) and haemophiliac (n = 8, Age = 15.0 ± 1.4 years; BMI = 20.4 ± 3.2 kg/m2) male adolescents was measured with a force platform for normal quiet stance lasting 30 s with open and closed eyes on hard and foam floor conditions. The ANOVA revealed a significant Group × Vision × Proprioception (F(1,18) = 5.861, p < 0.05) interaction. Both groups showed an increased centre of pressure (COP) speed when vision and proprioception are challenged. Planned comparisons revealed that the haemophiliac group oscillated at a faster COP speed than the healthy group when vision is altered in hard floor (1.11 ± 0.27 versus 0.76 ± 0.19 cm/s; p < 0.05) and foam floor (6.83 ± 1.68 versus 4.89 ± 1.05 cm/s; p < 0.01) conditions. More important, haemophiliac adolescents were more disturbed by the proprioceptive condition and had a significantly higher COP speed on the foam even if vision is available (3.02 ± 0.47 versus 2.34 ± 0.45 cm/s; p < 0.05) compared to the healthy adolescents. In conclusion, haemophilia clearly affects postural control in altered sensory conditions. Our results suggest that haemophilia has a negative impact on the capacity of male adolescents to adequately use proprioceptive information for posture control.

Impaired perception of surface tilt in progressive supranuclear palsy.

IntroductionProgressive supranuclear palsy (PSP) is characterized by early postural instability and backward falls. The mechanisms underlying backward postural instability in PSP are not understood. The aim of this study was to test the hypothesis that postural instability in PSP is a result of dysfunction in the perception of postural verticality.MethodsWe gathered posturography data on 12 subjects with PSP to compare with 12 subjects with idiopathic Parkinson’s Disease (PD) and 12 healthy subjects. Objective tests of postural impairment included: dynamic sensory perception tests of gravity and of surface oscillations, postural responses to surface perturbations, the sensory organization test of postural sway under altered sensory conditions and limits of stability in stance.ResultsPerception of toes up (but not toes down) surface tilt was reduced in subjects with PSP compared to both control subjects (p≤0.001 standing, p≤0.007 seated) and subjects with PD (p≤0.03 standing, p≤0.04 seated). Subjects with PSP, PD and normal controls accurately perceived the direction of gravity when standing on a tilting surface. Unlike PD and control subjects, subjects with PSP exerted less postural corrective torque in response to toes up surface tilts.DiscussionDifficulty perceiving backward tilt of the surface or body may account for backward falls and postural impairments in patients with PSP. These observations suggest that abnormal central integration of sensory inputs for perception of body and surface orientation contributes to the pathophysiology of postural instability in PSP.

Plantar tactile perturbations enhance transfer of split-belt locomotor adaptation.

Patterns of human locomotion are highly adaptive and flexible and depend on the environmental context. Locomotor adaptation requires the use of multisensory information to perceive altered environmental dynamics and generate an appropriate movement pattern. In this study, we investigated the use of multisensory information during locomotor learning. Proprioceptive perturbations were induced by vibrating tactors, placed bilaterally over the plantar surfaces. Under these altered sensory conditions, participants were asked to perform a split-belt locomotor task representative of motor learning. Twenty healthy young participants were separated into two groups: no-tactors (NT) and tactors (TC). All participants performed an overground walking trial, followed by treadmill walking including 18 min of split-belt adaptation and an overground trial to determine transfer effects. Interlimb coordination was quantified by symmetry indices and analyzed using mixed repeated-measures ANOVAs. Both groups adapted to the locomotor task, indicated by significant reductions in gait symmetry during the split-belt task. No significant group differences in spatiotemporal and kinetic parameters were observed on the treadmill. However, significant group differences were observed overground. Step and swing time asymmetries learned on the split-belt treadmill were retained and decayed more slowly overground in the TC group whereas in NT, asymmetries were rapidly lost. These results suggest that tactile stimulation contributed to increased lower limb proprioceptive gain. High proprioceptive gain allows for more persistent overground after effects, at the cost of reduced adaptability. Such persistence may be utilized in populations displaying pathologic asymmetric gait by retraining a more symmetric pattern.

Evaluation of postural steadiness in below-knee amputees when wearing different prosthetic feet during various sensory conditions using the Biodex® Stability System.

In recent years, computerized posturography has become an essential tool in quantitative assessment of postural steadiness in the clinical settings. The purpose of this study was to explore the ability of the Biodex(®) Stability System (BSS) to quantify postural steadiness in below-knee amputees. A convenience sample of 10 below-knee amputees participated in the study. The overall (OSI), anterior-posterior (APSI) and medial-lateral (MLSI) stability indexes as well as the percentage of time spent in left and right quadrants and four concentric zones were measured under altered sensory conditions while standing with solid ankle cushion heel (SACH), single-axis (SA) and energy storage and release (ESAR) feet. Significant difference was found between sensory conditions in SACH and ESAR feet for OSI (SACH, p = 0.002; ESAR, p = 0.005), APSI (SACH, p = 0.036; ESAR, p = 0.003) and MLSI (SACH, p = 0.008; ESAR, p = 0.05) stability indexes. The percentage of time spent in Zone A (0°-5°) was significantly greater than the other three concentric zones (p < 0.01). The loading time percentage on their intact limb (80%-94%) was significantly longer than the amputated limb (20%-6%) in all conditions for all three prosthetic feet. Below-knee amputees showed compromised postural steadiness when visual, proprioceptive or vestibular sensory input was altered. The findings highlight that the characteristics of postural stability in amputees can be clinically assessed by utilizing the outcomes produced by the BSS.

Deficits in sensory organization for postural stability in children with Tourette syndrome

Tourette syndrome (TS) is a childhood-onset developmental disorder characterized by involuntary motor and vocal tics. Previous studies have indicated that children with TS demonstrate postural control anomalies when standing. The aim of this study was to compare postural stability under normal and altered sensory conditions in children with TS and healthy control (HC) children. A convenience sample of twelve children with TS (9 boys and 3 girls; 9.4 ± 1.1 yr) and 12 HC age- and gender-matched children (9.2 ± 1.1 yr) participated in this study. The Sensory Organization Test (SOT) was used to assess postural stability under six altered sensory conditions (1. normal vision, fixed support; 2. eyes closed, fixed support; 3. vision sway-referenced, fixed support; 4. normal vision, support sway-referenced; 5. eyes closed, support surface sway-referenced; 6. both vision and support surface sway-referenced) using the SMART Balance Master® 8.2 (NeuroCom® International, Inc, Clackamas, OR, USA). The results showed significant differences between the two groups in conditions 5 and 6 (p=0.003 and 0.002, respectively). The mean composite equilibrium score in children with TS was significantly lower than that of HC children (p<0.000). The results suggested that children with TS had greater difficulty in maintaining postural stability, especially when vestibular information was challenged. The results of this study provide supporting evidence for possible deficits in impaired access to vestibular information and sensorimotor integration of postural control in children with TS.

Comparison of gait velocity and center of mass acceleration under conditions of disrupted somatosensory input from the feet during the navigation of obstacles in older adults with good and poor visual acuity

ObjectivesTo investigate the effects of good binocular visual acuity (GBVA) versus poor binocular visual acuity (PBVA), gait velocity and center of mass (COM) acceleration were evaluated in elderly individuals under three conditions, including the navigation of obstacles while walking with altered sensory conditions in the feet. MethodsNineteen elderly Korean women from community housing were enrolled in this study; nine participants had a binocular visual acuity (BVA) that was equal to or less than 0.4 logarithm of the minimum angle of resolution (logMAR), and 10 participants had a BVA that was equal to or greater than 0.3 logMAR. Participants were fitted with an accelerometer over the L3 spinal process and then walked on a GAITRite® system at a self-selected speed under three different conditions (barefoot, wearing mountain socks, and stepping over obstacles while wearing mountain socks). ResultsThe velocity of the GBVA group was significantly higher than was that of the PBVA group whereas the COM acceleration of the GBVA group was significantly lower than was that of the PBVA group. Both groups demonstrated significant differences in velocity and under the three experimental conditions and PBVA differed significantly under conditions 1 and 3 and under conditions 2 and 3. ConclusionsThese findings suggest that visual acuity (VA) in the elderly influences dynamic balance and gait velocity. Additionally, elderly participants with PBVA exhibited a greater sensitivity to altered sensory input, especially distorted sensory input from the feet in the presence of obstacles. Thus, elderly individuals with PBVA may require balance and gait training in diverse environments, including those involving the navigation of obstacles, to reduce the likelihood of falling.

Postural Control in Response to Altered Sensory Conditions in Persons With Dysvascular and Traumatic Transtibial Amputation

ObjectiveTo compare the postural control of persons with a dysvascular transtibial amputation and traumatic transtibial amputation with able-bodied adults with and without a dysvascular condition in altered sensory testing conditions. DesignCross-sectional study. SettingUniversity balance clinic. ParticipantsThe study participants (N=35) included: participants with a dysvascular transtibial amputation (n=9), participants with a traumatic transtibial amputation (n=9), age-matched able-bodied adults without a dysvascular condition (n=9), and able-bodied adults with a dysvascular condition (n=8). InterventionsSix Sensory Organization Test (SOT) conditions, which included standing with eyes open (condition 1) and closed (condition 2) on a static force platform with visual surround; standing with eyes open on a static force platform with movable visual surround (condition 3); standing with eyes open (condition 4) and closed (condition 5) on a movable force platform with static visual surround; and standing with eyes open on a movable force platform with movable visual surround (condition 6). Main Outcome MeasuresBilateral anteroposterior (AP) and mediolateral (ML) center of pressure variables, namely root mean square distance (RMSD) and mean velocity (mVel), for each of the 6 SOT conditions. ResultsThe dysvascular transtibial amputation group demonstrated a higher AP RMSD (P≤.04) on the sound side than did the able-bodied adults without a dysvascular condition and the able-bodied adults with a dysvascular condition in SOT conditions 1 and 2, respectively. Both the dysvascular transtibial amputation group and the traumatic transtibial amputation group demonstrated a higher AP RMSD (P≤.002) than the able-bodied adults without a dysvascular condition in SOT conditions 3 and 4. The dysvascular transtibial amputation group showed higher AP mVel (P≤.002) on the sound side for SOT conditions 2 and 3, whereas both amputation groups showed higher AP mVel for SOT conditions 1 and 4 than the able-bodied adults with and without a dysvascular condition. ConclusionsPostural control of the dysvascular transtibial amputation group was not different than the traumatic transtibial amputation group in challenging sensory conditions. However, when compared with the groups of able-bodied adults with and without a dysvascular condition, postural strategies distinct with amputation etiology were observed.

Postural balance under normal and altered sensory conditions in normal-weight and overweight children

Background Little or no research has been done in the overweight child on the relative contribution of multisensory information to maintain postural stability. Therefore, the purpose of this study was to investigate postural balance control under normal and experimentally altered sensory conditions in normal-weight versus overweight children. Methods Sixty children were stratified into a younger (7–9 yr) and an older age group (10–12 yr). Participants were also classified as normal-weight (n = 22) or overweight (n = 38), according to the international BMI cut-off points for children. Postural stability was assessed during quiet bilateral stance in four sensory conditions (eyes open or closed, normal or reduced plantar sensation), using a Kistler force plate to quantify COP dynamics. Coefficients of variation were calculated as well to describe intra-individual variability. Findings Removal of vision resulted in systematically higher amounts of postural sway, but no significant BMI group differences were demonstrated across sensory conditions. However, under normal conditions lower plantar cutaneous sensation was associated with higher COP velocities and maximal excursion of the COP in the medial-lateral direction for the overweight group. Regardless of condition, higher variability was shown in the overweight children within the 7–9 yr old subgroup for postural sway velocity, and more specifically medial–lateral velocity. Interpretation In spite of these subtle differences, results did not establish any clear underlying sensory organization impairments that may affect standing balance performance in overweight children compared to normal-weight peers. Consequently, it is believed that other factors account for overweight children's functional balance deficiencies.

Direct parameterization of postural stability during quiet upright stance: Effects of age and altered sensory conditions

The purpose of this study was to determine the relationship between measures of local dynamic stability (LDS) during upright stance and both descriptive measures of postural sway and a scaling index ( α) derived from detrended fluctuation analysis. Center of pressure (COP) time series were obtained from healthy participants (16 young and 16 older) during upright quiet stance. Vision and somatosensation were altered by eye closure and standing on a compliant surface, respectively. A non-linear time-series analysis method was used to compute three LDS parameters from the COP data: A which was defined as the COP excursion range in state space, and τ S and τ L which were defined as the divergence rates over short- and long-term timescales, respectively. LDS parameters, descriptive COP measures, and α had generally consistent sensitivities to age and/or altered sensory conditions. Age x sensory condition interactions, however, had distinct effects on LDS parameters compared to the other COP-based measures. Older individuals exhibited faster divergence rates while having similar magnitudes of A, compared to young individuals. These results suggest that older individuals stiffen the musculoskeletal system via increased muscle activity, perhaps as an age-related postural adaptation. In addition, correlations between LDS parameters and other COP measures were relatively small ( r 2⩽0.29). Hence, LDS parameters ( A, τ S and τ L) provide distinct information on postural control and stability, supplementing other COP-based measures.

Sensitivity and Reliability of Local Dynamic Stability: Effects of Age and Altered Sensory Conditions

Local dynamic stability was investigated during quiet upright stance with respect to age and altered sensory conditions. From center of pressure (COP) trajectories, the largest Lyapunov exponent (Λmax) was extracted to directly parameterize local dynamic stability, and the reliability of Λmax was assessed using the intra-class correlation coefficient (ICC). Thirty two participants volunteered for upright quiet stance trials. Vision and somatosenstaion were experimentally altered: vision was modified by eye closure, and somatosensation by using both a hard surface (HS) and a soft surface (SS). Age and vision had main effects on Λma, and the age x vision and vision x surface interaction effects were also significant. In general, older participants were less stable (i.e., higher Λmax) than younger, and altered sensory information resulted in a decrease in stability. Reliability was higher for older versus younger participants. Use of Λmax enabled a direct assessment of age-related differences in local dynamic stability and effects of altered sensory conditions. Such non-linear measures can provide additional information to that available from traditional COP-based analyses.

Standing balance of children with developmental coordination disorder under altered sensory conditions

Maintenance of standing balance requires that sensory inputs be organized with the motor system. Current data regarding the influence of sensory inputs on standing balance in children with developmental coordination disorder (DCD) are limited. This study compared the influence of sensory organization and each sensory input on the standing stability between a group of 20 children, 4–6 years old, with DCD and an age- and gender-matched control group of 20 children. Three types of visual inputs (eyes open, eyes closed, or unreliable vision) and two types of somatosensory inputs (fixed or compliant foot support) were varied factorially to yield six sensory conditions. Standing stability was measured with a Kistler force plate for 30s and expressed as the center of pressure sway area. The results showed that the standing stability of the children with DCD was significantly poorer than that of the control children under all sensory conditions, especially when the somatosensory input was unreliable (compliant foot support) compared to when it was reliable (fixed foot support). The effectiveness of an individual sensory system, when it was the dominant source of sensory input, did not significantly differ between the groups. The results suggest that children with DCD experience more difficulty coping with altered sensory inputs, and that such difficulty is more likely due to a deficit in sensory organization rather than compromised effectiveness of individual sensory systems.

Balance sensory organization in children with profound hearing loss and cochlear implants

(1) To determine the feasibility of the use of a modified postural control test under altered sensory conditions in children over 8 years of age, and (2) to assess how deaf children use sensory information for postural control when they have normal or abnormal vestibular responses, and if hearing input from a unilateral cochlear implant, changes their postural behavior. We selected 36 children, 8 to 11 years of age, with congenital or early-acquired profound sensorineural hearing loss, 13 of them with unilateral cochlear implantation and 22 normal-hearing children. The Postural Control (PC) test consists of a force platform with 2 stimulation paradigm conditions: (1) standing on the platform with opened eyes; (2) standing on foam placed on the force platform with closed eyes. Implanted children were tested with the implant turn on and turn off in this condition, in order to evaluate eventual change in the postural control parameters when they have hearing habilitation. The body center of pressure distribution area (COP) and the body sway velocity (SV) were the parameter to evaluate the postural control. Deaf children were classified into two groups according with the vestibular responses: group A (n=28) Children with normal vestibular rotary responses; group B (n=8) children with hypoactive responses. Children in group A had diagnoses of syndromic and non-syndromic hereditary deafness, and children in group B had inner ear malformations, post-meningitis deafness, and one child had non-syndromic hereditary deafness with hypoactive vestibular response. In condition 1, when vestibular, somatosensory and visual information were enabled, the COP and SV values did not show any statistically significant differences between groups A, B and control. In condition 2, when visual information was removed and the somatosensory input strongly modified by standing on the foam, group B showed significant higher COP and SV values than groups A and control (p<0.05). In addition, the scalograms by wavelets of children in group B had higher amplitudes increasing the sway frequencies contents up to 3 Hz, not allowing them to maintain the up right stance in similar stimulation than in condition. Implanted children of the group A and B with the implant turn on, in the condition 2, did not show any significant difference in the SV, comparing when they had the implanted turn off. Group A p=0.395 and group B p=0.465 (Wilcoxon ranked test). These findings allow us to confirm that this postural test can be performed in children over 8 years old. Also our results suggest that deaf children with associated hypoactive vestibular responses included in our study, despite the etiology of the deafness, primarily use visual and somatosensory information to maintain their postural control. Hearing habilitation with a unilateral cochlear implant has no effect on the observed sensory organization strategy.