Does somatosensation change with age in children and adolescents? A systematic review

The Feel of Speech: Multisystem and Polymodal Somatosensation in Speech Production

PURPOSE

The oral structures such as the tongue and lips have remarkable somatosensory capacities, but understanding the roles of somatosensation in speech production requires a more comprehensive knowledge of somatosensation in the speech production system in its entirety, including the respiratory, laryngeal, and supralaryngeal subsystems. This review was conducted to summarize the system-wide somatosensory information available for speech production.

METHOD

The search was conducted with PubMed/Medline and Google Scholar for articles published until November 2023. Numerous search terms were used in conducting the review, which covered the topics of psychophysics, basic and clinical behavioral research, neuroanatomy, and neuroscience.

RESULTS AND CONCLUSIONS

The current understanding of speech somatosensation rests primarily on the two pillars of psychophysics and neuroscience. The confluence of polymodal afferent streams supports the development, maintenance, and refinement of speech production. Receptors are both canonical and noncanonical, with the latter occurring especially in the muscles innervated by the facial nerve. Somatosensory representation in the cortex is disproportionately large and provides for sensory interactions. Speech somatosensory function is robust over the lifespan, with possible declines in advanced aging. The understanding of somatosensation in speech disorders is largely disconnected from research and theory on speech production. A speech somatoscape is proposed as the generalized, system-wide sensation of speech production, with implications for speech development, speech motor control, and speech disorders.

Prior visual experience increases children's use of effective haptic exploration strategies in audio-tactile sound-shape correspondences

Sound-shape correspondence refers to the preferential mapping of information across the senses, such as associating a nonsense word like bouba with rounded abstract shapes and kiki with spiky abstract shapes. Here we focused on audio-tactile (AT) sound-shape correspondences between nonsense words and abstract shapes that are felt but not seen. Despite previous research indicating a role for visual experience in establishing AT associations, it remains unclear how visual experience facilitates AT correspondences. Here we investigated one hypothesis: seeing the abstract shapes improve haptic exploration by (a) increasing effective haptic strategies and/or (b) decreasing ineffective haptic strategies. We analyzed five haptic strategies in video-recordings of 6- to 8-year-old children obtained in a previous study. We found the dominant strategy used to explore shapes differed based on visual experience. Effective strategies, which provide information about shape, were dominant in participants with prior visual experience, whereas ineffective strategies, which do not provide information about shape, were dominant in participants without prior visual experience. With prior visual experience, poking-an effective and efficient strategy-was dominant, whereas without prior visual experience, uncategorizable and ineffective strategies were dominant. These findings suggest that prior visual experience of abstract shapes in 6- to 8-year-olds can increase the effectiveness and efficiency of haptic exploration, potentially explaining why prior visual experience can increase the strength of AT sound-shape correspondences.

Somatosensation and motor performance in the less-affected and more-affected hand of unilateral cerebral palsy children: a cross-sectional study

PURPOSE

This study aimed to examine motor performance and somatosensory processing of unilateral cerebral palsy (UCP) children in both the less-affected hand and the more-affected hand. This study is also aimed at analysing the somatosensory proccessing in the more-affected hand in relation to age and damaged hemisphere.

MATERIALS AND METHODS

Forty-seven children aged from 6 to 15 years (UCP = 23; TD = 24) were recruited. Grip strength, pinch strength, Box and Block Test and Jebsen Taylor Hand Function Test were used to analyse motor performance. A comprehensive somatosensory assessment battery was included: tactile registration, unilateral, bilateral and spatio-temporal perception, haptic recognition, texture perception, proprioception, pressure pain threshold and functional sensitivity.

RESULTS

UCP children exhibited lower performance in all aspects of motor performance measured in both the less-affected hand and the more-affected hand, except grip strength in the less-affected hand. Significant differences were found for all tests included in the somatosensory assessment in both the less-affected hand and the more-affected hand, except unilateral perception tests in the less-affected hand.

CONCLUSIONS

UCP children present difficulties in motor performance and somatosensory processing not only in the more-affected hand, but also in the less-affected hand. Somatosensation may be a critical driver of functional performance.Implications for rehabilitationThe less-affected hand of children with unilateral cerebral palsy should be included in both assessment and intervention programmes.Somatosensory processing should be assessed through a comprehensive battery, both in the less-affected hand and in the more-affected hand of unilateral cerebral palsy children.Somatosensory treatment must be taken into account if functional performance in the activities of daily living of unilateral cerebral palsy children is to be improved.

The feeling of "kiki": Comparing developmental changes in sound-shape correspondence for audio-visual and audio-tactile stimuli

Sound-shape crossmodal correspondence, the naturally occurring associations between abstract visual shapes and nonsense sounds, is one aspect of multisensory processing that strengthens across early childhood. Little is known regarding whether school-aged children exhibit other variants of sound-shape correspondences such as audio-tactile (AT) associations between tactile shapes and nonsense sounds. Based on previous research in blind individuals suggesting the role of visual experience in establishing sound-shape correspondence, we hypothesized that children would show weaker AT association than adults and that children's AT association would be enhanced with visual experience of the shapes. In Experiment 1, we showed that, when asked to match shapes explored haptically via touch to nonsense words, 6- to 8-year-olds exhibited inconsistent AT associations, whereas older children and adults exhibited the expected AT associations, despite robust audio-visual (AV) associations found across all age groups in a related study. In Experiment 2, we confirmed the role of visual experience in enhancing AT association; here, 6- to 8-year-olds could exhibit the expected AT association if first exposed to the AV condition, whereas adults showed the expected AT association irrespective of whether the AV condition was tested first or second. Our finding suggests that AT sound-shape correspondence is weak early in development relative to AV sound-shape correspondence, paralleling previous findings on the development of other types of multisensory associations. The potential role of visual experience in the development of sound-shape correspondences in other senses is discussed.

Somatosensory discrimination impairment in children with hemiplegic cerebral palsy as measured by the sense_assess© kids

INTRODUCTION

To characterise somatosensory discrimination impairment of the upper-limb across domains of tactile discrimination, limb position sense and haptic object recognition using the sense_assess© kids and examine associations with upper-limb motor performance in children with hemiplegic cerebral palsy (CP).

METHODS

The sense_assess© kids was administered at one timepoint to 28 children, aged 6-15.5 years (M = 10.1, SD = 2.4), with hemiplegic CP (right hemiplegia n = 15) and Manual Ability Classification System Levels I (n = 11) and II (n = 17). Unimanual motor performance was quantified using the Box and Block Test.

RESULTS

Tactile discrimination was impaired in 18, limb position sense in 20, and haptic object recognition was impaired in 21 of 28 children. Over 80% (23/28) of children had impaired somatosensory discrimination in one or more domains. Low to moderate correlations were observed between each measure of somatosensory discrimination and motor performance. Manual ability classification was associated with limb position sense and haptic object recognition. A moderate inverse correlation (r = -.57, p < .01) exists between the number of somatosensory domains impaired and motor performance.

CONCLUSION

The frequency of somatosensory impairment in the upper limb of children in our sample was high and associated with manual ability, suggesting a need for routine assessment of somatosensation in this population.

Movement detection thresholds reveal proprioceptive impairments in developmental dyslexia

Developmental dyslexia is associated with vision and hearing impairments. Whether these impairments are causes or comorbidities is controversial. Because both senses are heavily involved in reading, cognitive theories argue that sensory impairments are comorbidities that result from a lack of reading practice. Sensory theories instead argue that this is sensory impairments that cause reading disabilities. Here we test a discriminant prediction: whether sensory impairments in developmental dyslexia are restrained to reading-related senses or encompass other senses. Sensory theories predict that all senses are affected, whereas, according to the lack of reading practice argument, cognitive theories predict that only reading-related senses are affected. Using a robotic ergometer and fully automatized analyses, we tested proprioceptive acuity in seventeen dyslexic children and seventeen age-matched controls on a movement detection task. Compared to controls, dyslexics had higher and more variable detection thresholds. For the weakest proprioceptive stimuli, dyslexics were twice as long and twice as variable as controls. More, proprioceptive acuity strongly correlated with reading abilities, as measured by blind cognitive evaluations. These results unravel a new sensory impairment that cannot be attributed to a lack of reading practice, providing clear support to sensory theories of developmental dyslexia. Protocol registration: This protocol is part of the following registration, ClinicalTrials.gov Identifier: NCT03364010; December 6, 2017.

Hand size representation in healthy children and young adults

Whereas we experience our body as a coherent volumetric object, the brain appears to maintain highly fragmented representations of individual body parts. Little is known about how body representations of hand size and shape are built and evolve during infancy and young adulthood. This study aimed to investigate the effect of hand side, handedness, and age on the development of central hand size representation. The observational study with comparison groups was conducted with 90 typically developing Belgian school children and young adults (48 male and 42 female; age range = 5.0-23.0 years; 49 left-handed and 41 right-handed). Participants estimated their hand size and shape using two different tasks. In the localization task, participants were verbally cued to judge the locations of 10 anatomical landmarks of an occluded hand. An implicit hand size map was constructed and compared with actual hand dimensions. In the template selection task, the explicit hand shape was measured with a depictive method. Hand shape indexes were calculated and compared for the actual, implicit, and explicit conditions. Participants were divided into four age groups (5-8 years, 9-10 years, 11-16 years, and 17-23 years). Implicit hand maps featured underestimation of finger length and overestimation of hand width, which is already present in the youngest children. Linear mixed modeling revealed no influence of hand side on finger length underestimation; nonetheless, a significant main effect of age (p = .001) was exposed. Sinistrals aged 11 to 16 years showed significantly less underestimation (p = .03) than dextrals of the same age. As for the hand shape, the implicit condition differed significantly with the actual and explicit conditions (p < .001). Again, the implicit shape index was subjected to handedness and age effects, with significant differences being found between sinistrals and dextrals in the age groups of 9 and 10 years (p = .029) and 11 to 16 years (p < .001). In conclusion, the implicit metric component of the hand representation in children and young adults is misperceived, featuring shortened fingers and broadened hands since a very young age. Crucially, the finger length underestimation increases with age and shows a different developmental trajectory for sinistrals and dextrals. In contrast, the explicit hand shape is approximately veridical and seems immune from age and handedness effects. This study confirms the dual character of somatoperception and establishes a point of reference for children and young adults.

Robotic Assessments of Proprioception and the Impact of Age

We examined different methods of robotic proprioception assessment and provided comparison with the wrist position sense test gold standard assessment. The aim is to determine which of the assessments are the most reliable and would be acceptable for clinical evaluation. 31 children between six and sixteen participated in a pilot assessment trial and completed all four of the assessments. The assessments included the manual and robotic versions of the wrist position sense test, the joint position matching assessment and the psychometric threshold determination assessment. There was not a significant difference between the manual and robotic wrist position sense tests but there were significant differences with the other assessments. The study also examined the effect of age on the different assessments and found that three of the assessments, excluding the joint position matching assessment, can differentiate between children of different ages. This study concludes that the significant differences between the assessments indicates that proprioception in the wrist is complex and multifaceted. Further studies will likely need to include multiple assessments to gain a more complete understanding of proprioception.

Physiological Profile Assessment of Posture in Children and Adolescents with Autism Spectrum Disorder and Typically Developing Peers

A sound postural system requires sensorimotor integration. Evidence suggests that individuals with Autism Spectrum Disorder (ASD) present sensorimotor integration impairments. The Physiological Profile Assessment (PPA) can be used to evaluate postural capacity assessing five physiological subsets (i.e., vision, reaction time, peripheral sensation, lower limb strength, balance); however, no studies applied the PPA in young individuals. Therefore, this study aimed to investigate the PPA in children and adolescents with ASD compared with age-matched typically developing (TD) individuals and examine the relationship between the PPA subset within the ASD and TD participants according to different age groups. Percentiles from the PPA were obtained from the TD children and adolescents (n = 135) for each test. Performances of the individuals with ASD (n = 18) were examined relative to the TD percentiles. ASD participants' scores were above the 90th percentile (i.e., poor performance) in most sensory, motor and balance parameters. Performance in most of the PPA tests significantly improved with older age in the TD group but not in the ASD group. The study findings support the use of the PPA in TD children and adolescents while further research should investigate postural capacity in a larger ASD sample to enhance the understanding of sensorimotor systems contributing to compromised postural control.

Experience of Engagement in a Somatosensory Discrimination Intervention for Children with Hemiplegic Cerebral Palsy: A Qualitative Investigation

Background: To successfully modify an intervention from an adult population for use with children with cerebral palsy, it is important to understand the components that support a child's motivation and engagement. Method: Ten children who had participated in the Sense© intervention (mean age = 11 years 2 m [SD = 2 years]; four males; Manual Ability Classification System level I = 1, II = 9) and their primary caregivers (N = 11, 10 females) were interviewed. Transcripts were analyzed using framework analysis. Results: Key themes were identified in the core domains of the Synthesis of Child, Occupational Performance and Environment in Time model. Child: children's somatosensory discrimination ability improved; Motivation: incorporating child's goals was essential, as were real-world gains; Environmental: parents were interested in having more involvement in the intervention. Conclusion: The most engaging elements of the intervention for children were the attainment of their self-selected goals. Opportunities to modify the intervention for improved partnership with parents were identified.

Haptic Exploratory Procedures of Children and Youth with and without Cerebral Palsy

Aims: Compare haptic exploratory procedures (EPs) and exploratory movements (EMs) of children. This study also tested the interrater reliability of a novel digital recording method. Methods: Participants were 31 children with typical development (TD) (aged 6 years 1 month to 15 years 9 months; 14 male) and 23 children with spastic unilateral cerebral palsy (CP) (aged 6 years to 15 years 5 months; 13 males; right hemiplegia, n = 12). Results: There were no statistically significant differences between groups for expected EP (p = .15), additional EPs (p = .78), or EMs (p = .69) but there was for mean duration of exploration (p < .001) and accuracy (p < .001). This suggests that although children with CP performed similar haptic EPs for each object as children with TD, they took more time and were less accurate in their identification. There was substantial agreement between the two raters' observations of expected EP, κ = .64, p < .0005. Conclusion: Children with CP performed similar haptic EPs as their TD peers. However, despite similarities, the results indicate that for children with CP manual ability was not the primary determinant of accuracy or speed of identification. This study provides evidence for a reliable method of recording haptic EPs.

Differences in response inhibition processes between adolescents and adults are modulated by sensory processes

Response inhibition processes undergo strong developmental changes. The same is true for sensory processes, and recent evidence shows that there also within-modality differences in the efficacy to trigger motor response inhibition. Yet, modulatory effects of within-modality differences during age-related changes in response inhibition between adolescence and adulthood are still indeterminate. We investigated this question in a system neurophysiological approach combining analysis of event-related potentials (ERPs) with temporal EEG signal decomposition and source localization processes. We used the somatosensory system to examine possible within-modality differences. The study shows that differences in response inhibition processes between adolescents and adults are modulated by sensory processes. Adolescents show deficient response inhibition when stimuli triggering these mechanisms are processed via SI somatosensory areas, compared to SII somatosensory areas. Opposed to this, no differences between adolescents and adults are evident, when response inhibition processes are triggered via SII cortical regions. The EEG data suggests that specific neurophysiological subprocesses are associated with this. Adolescents seem to encounter problems assigning processing resources to integrate motor with tactile information in posterior parietal areas when this information is processed via SI. Thus, basic perceptual and age-related processes interactively modulate response inhibition as an important instance of cognitive control.

Neurophysiological variability masks differences in functional neuroanatomical networks and their effectiveness to modulate response inhibition between children and adults

Executive functions are well-known to undergo developmental changes from childhood to adulthood. Considerable efforts have been made to elucidate the affected system neurophysiological mechanisms. But while it is well-known that developmental changes affect intra-individual variability, this potential bias has largely been neglected when investigating the neurophysiology underlying developmental differences between children and adults. We hypothesize that due to differences in intra-individual variability of neural processes between children and adults, reliable group differences will only be evident after accounting for intra-individual variability in neurophysiological processes. We, therefore, investigate response-inhibition processes as an important instance of executive control in children (between 10 and 14 years) and adults (between 20 and 29 years) and decompose EEG data on the basis of the latency and temporal variability. This was combined with source localization. Children showed more impulsive behavior than adults. Importantly, a reliable match between the neurophysiological and behavioral data could only be found when accounting for intra-individual variability in the EEG data. These decomposed data showed that children and adults use similar neurophysiological mechanisms at the response selection level to accomplish inhibitory control, but seem to engage different neuroanatomical structures to do so according to source localization results: In adults, these processes were related to the medial frontal cortex. In children, the same processes were reflected in a shift of the scalp topography and related to the superior parietal cortex. These shifts in neural networks were associated with lower effectiveness in exerting inhibitory control. However, these differences in the functional neuroanatomical architecture can only be seen when intra-individual variability is taken into account.