Prechtl's method to assess general movements: Inter-rater reliability during the preterm period.

INTRODUCTION: Prechtl's method (GMA) is a test for the functional assessment of the young nervous system. It involves a global and a detailed assessment of the general movements (GMs) and has demonstrated validity. Data on the reliability of both assessments in the preterm period are scarce. This study aimed to evaluate the inter-rater reliability for the global and detailed assessments of the preterm writhing GMA. MATERIALS AND METHODS: The study participants were 69 infants born at <37 gestational weeks and admitted to the neonatal intensive care unit. They were randomly assigned to five pairs of raters. Raters assessed infants' GMs using preterm videos. Outcome variables were (a) the GMs classification (normal versus abnormal; normal versus abnormal subcategories) and (b) the general movements optimality score (GMOS), obtained through the global and detailed assessments. The Gwet's AC1 and the intraclass correlation coefficient (ICC) were calculated for the GMs classification and the GMOS, respectively. RESULTS: The global assessment presented an AC1 = 0.84 [95% CI = 0.54,1] for the GMs binary classification and an AC1 = 0.67 [95% CI = 0.38,0.89] for the GMs classification with abnormal subcategories. The detailed assessment presented an ICC = 0.72 [95% CI = 0.39,0.90] for the GMOS. CONCLUSIONS: Inter-rater reliability was high and substantial for the global assessment and good for the detailed assessment. However, the small sample size limited the precision of these estimates. Future research should involve larger samples of preterm infants to improve estimate precision. Challenging items such as assessing the neck and trunk, poor repertoire GMs, and tremulous movements may impact the preterm writhing GMA's inter-rater reliability. Therefore, ongoing training and calibration among raters is necessary. Further investigation in clinical settings can enhance our understanding of the preterm writhing GMA's reliability.

Time processing in neurological and psychiatric conditions.

A central question in understanding cognition and pathology-related cognitive changes is how we process time. However, time processing difficulties across several neurological and psychiatric conditions remain seldom investigated. The aim of this review is to develop a unifying taxonomy of time processing, and a neuropsychological perspective on temporal difficulties. Four main temporal judgments are discussed: duration processing, simultaneity and synchrony, passage of time, and mental time travel. We present an integrated theoretical framework of timing difficulties across psychiatric and neurological conditions based on selected patient populations. This framework provides new mechanistic insights on both (a) the processes involved in each temporal judgement, and (b) temporal difficulties across pathologies. By identifying underlying transdiagnostic time-processing mechanisms, this framework opens fruitful avenues for future research.

Stimulating the motor development of very premature infants: effects of early crawling training on a mini-skateboard.

Aim: To examine the effects of an early home-based 8-week crawling intervention performed by trained therapists on the motor and general development of very premature infants during the first year of life. Methods: At term-equivalent age, immediately following discharge from the Neonatal Intensive Care Unit (NICU), we randomly allocated 44 premature infants born before 32 weeks' gestation without major brain damage to one of three conditions in our intervention study: crawling on a mini-skateboard, the Crawliskate (Crawli), prone positioning control (Mattress), or standard care (Control). The Crawli and Mattress groups received 5 min daily at-home training administered by trained therapists for 8 consecutive weeks upon discharge from the NICU. The outcomes of greatest interest included gross motor development (Bayley-III) at 2, 6, 9, and 12 months (primary outcome) corrected age (CA), mature crawling at 9 months CA and general development at 9 and 12 months CA [Ages and Stages Questionnaires-3 (ASQ-3)]. The study was registered at www.clinicaltrials.gov; registration number: NCT05278286. Results: A 3 (Condition) × 4 (Age) repeated measures ANOVA revealed that Crawli group infants had significantly higher Bayley-III gross motor development scores than Mattress and Control group infants. Crawli group infants also scored significantly higher on groups of Bayley-III items related to specific motor skills than infants in the other groups, including crawling at 9 months CA. We found significant differences in favor of the Crawli group in separate one-way ANOVAs at each of the ages we examined. A 3 (Condition) × 2 (Age) repeated measures ANOVA revealed that the Crawli group scored significantly higher than the Control group for the ASQ-3 total score and communication score and significantly higher for the fine motor score than the Control and Mattress groups. We found additional significant differences in favor of the Crawli group for other dimensions of the ASQ-3 in separate one-way ANOVAs at 9 and 12 months CA. Interpretation: Early crawling training on a Crawliskate provides an effective way to promote motor and general development in very premature infants. The findings also provide clear evidence for a link between newborn crawling and more mature crawling later in development.

Newborns modulate their crawling in response to their native language but not another language.

Human newborns can propel themselves to their mother's breast when positioned skin to skin on her abdomen just after birth. For decades, researchers have considered this primitive crawling behavior a spinal reflex, immune to supra spinal control. However, recent research suggests that neonatal crawling is already responsive to visual and olfactory stimuli processed at a supra spinal level. Here we report that a few hours post birth, French newborns can also modulate their crawling in response to their native language - a source of information that is processed supra-spinally. The crawling patterns of 23 French-born newborns were recorded on video and via an infrared motion capture system during two randomly ordered 2-min trials. The newborns were secured on a mini skateboard to facilitate arm and leg movements during their crawling propulsion. They heard a repetitive sequence of the same sentences either in French, their native language, or in English, a rhythmically different and hence discriminable unfamiliar language, on each trial. In French, compared to English, crawling was enhanced, with significantly more arm and leg steps and significantly more and larger trunk rotations in the cephalo-caudal axis. Moreover, newborns rotated their heads and trunk toward the appropriate loud speaker when hearing French but not English. These preliminary findings suggest that newborn crawling is not a simple stereotyped reflex under spinal control, but a complex pattern that can be modulated in response to higher-order, supra-spinally processed stimuli. The findings open fascinating questions about the range of stimuli to which newborn crawling is responsive.

Rhythmic training, literacy, and graphomotor skills in kindergarteners.

Introduction: The aim of this manuscript is twofold: first, to investigate the relationship between rhythmic, phonological and graphomotor skills in kindergarten children; and second, to evaluate the possible impact of rhythmic training on the two other skills. Methods: To that end, we selected a sample of 78 children in Québec. Forty-two children received rhythmic training (experimental group) and 34 arts training (active control group) during the same period (10 weeks). Before and after training, children in both groups were assessed for general skills (forward and backward memory span, vocabulary, non-verbal ability), rhythmic skills (synchronization and discrimination tasks), literacy skills (phonological skills - syllable counting, syllable deletion, rhyme discrimination - and invented spelling skills) and graphomotor skills (legibility of letter writing, quality of copying of geometric shapes). Results: Results showed correlations between the child's rhythmic and literacy skills, as well as between rhythm synchronization and pen pressure. In addition, rhythmic training showed improvement in rhythmic abilities, but this did not transfer to literacy or graphomotor development (apart from a significant increase in the duration of pauses in both groups at post-test, with a larger improvement for the rhythm group). Discussion: These results are discussed in terms of duration and intensity of learning, and they highlight the possible benefits of informal rhythm practices in the classroom.

[The mechanisms involved in rocking toddlers]. / Les mécanismes mis en jeu dans les bercements des tout-petits.

If the tactile modality is fundamental in the infant's experience, there is a particular situation in which it is mobilized: rocking. Carrying a baby in one's arms or trying to soothe him will spontaneously lead the adult to rock him, whatever his culture. The ways of carrying out this rhythmic movement are varied, but all are characterized by a synchronous combination of somesthesic and vestibular stimulations repeated at regular intervals. The specificities of the tactile, vestibular and temporal modalities involved in rocking highlight the way in which rocking provides an essential support to the sensory and social development of the infant.

Effects of Early Motor Interventions on Gross Motor and Locomotor Development for Infants at-Risk of Motor Delay: A Systematic Review.

Aim: To systematically examine the effect of early motor interventions on motor and locomotor development in infants <1 year of age with motor developmental disability or at risk of motor delay. Methods: Pertinent literature from January 2000 to September 2021 was identified by searching the PubMed, Embase, Cochrane, Pedro and Web of Science databases. Selection criteria included interventions starting before 12 months corrected age. Methodological quality was assessed with AACPDM criteria, Mallen score and Cochrane risk of bias methodology. Evaluation procedure was performed using PRISMA protocol (PICO approach) and AMSTAR-2. This review was preregistered in PROSPERO (CRD42021286445). Results: Ten articles met the inclusion criteria; seven had moderate to strong methodological quality. The interventions included treadmill training (n = 3), crawling training (n = 1), "tummy time" (n = 1), physical therapy with neonatal developmental program (n = 1) or Bobath approach (n = 1), treadmill training combined with active leg movements (n = 2) or Bobath physiotherapy (n = 1). The three key characteristics of effective interventions that emerged from the review were: (1) the infants' disability or risk of delay was well-defined; (2) the protocol was standardized and easy to replicate; (3) infants were required to make active movements. Conclusion: There is an urgent need for additional high-quality studies on the effects of early motor interventions on the gross motor and locomotor development of infants with a range of disabilities or risks for delay. Suggestions for future research are outlined.

The Importance of Rhythmic Stimulation for Preterm Infants in the NICU.

The fetal environment provides the fetus with multiple potential sources of rhythmic stimulation that are not present in the NICU. Maternal breathing, heartbeats, walking, dancing, running, speaking, singing, etc., all bathe the fetus in an environment of varied rhythmic stimuli: vestibular, somatosensory, tactile, and auditory. In contrast, the NICU environment does not offer the same proportion of rhythmic stimulation. After analyzing the lack of rhythmic stimulation in the NICU, this review highlights the different proposals for vestibular and/or auditory rhythmic stimulation offered to preterm infants alone and with their parents. The focus is on the beneficial effects of auditory and vestibular stimulation involving both partners of the mother-infant dyad. A preliminary study on the influence of a skin-to-skin lullaby on the stability of maternal behavior and on the tonic emotional manifestations of the preterm infant is presented as an example. The review concludes with the importance of introducing rhythmic stimulations in the NICU.

Newborn crawling and rooting in response to maternal breast odor.

A growing literature shows that perception and action are already tightly coupled in the newborn. The current study aimed to examine the nature of the coupling between olfactory stimuli from the mother and the newborn's crawling and rooting (exploratory movements of the head). To examine the coupling, the crawling and rooting behavior of 28 2-day-old newborns were studied while they were supported prone on a mobility device shaped like a mini skateboard, the Crawliskate®, their head positioned directly on top of a pad infused with either their mother's breast odor (Maternal) or the odor of water (Control). Video and 3D kinematic analyses of the number and types of limb movements and quantification of displacement across the surface revealed that newborns are significantly more efficient crawlers when they smell the maternal odor, moving greater distances although performing fewer locomotor movements. In addition, the newborns made significantly more head rooting movements in the presence of the maternal odor. These findings suggest that the circuitry underlying quadrupedal locomotion and exploratory movements of the head is already adaptable to olfactory information via higher brain processing. Moreover, the coupling between olfaction and the two action systems, locomotion and rooting, is already differentiated. As crawling enables the newborn to move toward the mother's breast immediately after birth and facilitates mother-infant interaction, the results of this study highlight the potential value of using maternal odors to stimulate mobility in infants at risk of motor delay and/or deprived of this odor when born prematurely.

What Does Prone Skateboarding in the Newborn Tell Us About the Ontogeny of Human Locomotion?

The crawling behavior of sixty 2-day-old newborns was studied while they were supported prone on a mini skateboard and on a pediatric mattress without additional support. Analyses of the number and types of limb movements and their characteristics, the coactivation of limb pairs, and the displacement across the surface, revealed that newborns can crawl with locomotor patterns similar to those documented during quadrupedal locomotion in animals and human adults. This was particularly apparent on the skateboard. This discovery suggests that locomotor circuitry underlying quadrupedal locomotion develops during fetal life. Drawing upon other evidence for a quadrupedal organization underlying bipedal gait, we argue that early quadrupedal training may enhance interventions designed to hasten the onset of independent walking.

Why does infant stepping disappear and can it be stimulated by optic flow?

Two independent experiments (n = 22 and n = 22) showed that 2-month-old infants displayed significantly more stepping movements when supported upright in the air than when supported with their feet contacting a surface. Air- and surface-stepping kinematics were quite similar (Experiment 2). In addition, when data were collapsed across both experiments, more air steps and more donkey kicks were seen when infants were exposed to optic flows that specified backward compared to forward translation. The findings challenge the currently accepted heavy legs explanation for the disappearance of stepping at 2 months of age and raise new questions about the visual control of stepping.

Young children's difficulties in switching from rhythm production to temporal interval production (>1 s).

This study examined the young children's abilities to switch from rhythm production, with short inter-tap intervals (ITIs), to temporal interval production, with long ITI (>1 s), in a sensorimotor synchronization task. Children aged 3- and 5-year-olds were given six sessions of synchronization. In a control group, they had to synchronize their ITI to an inter-stimulus interval (ISI) of 4 s. In the experimental group, they must progressively increase their ITI for one session to the next (from 0.4 to 4.0-s ISI). Our results showed that the 5-year-olds produced longer ITI that the 3-year-olds in synchronization. However, the value of ITI in the 5-year-olds never exceeded 1.5 s, with more variable ITI in the control than in the experimental group. In addition, at 5 years, boys had more difficulties than girls in changing their tapping rhythm. These results suggest a temporal window in sensorimotor synchronization, beyond which the rhythm is lost and the synchronization becomes difficult.

Rhythm perception, production, and synchronization during the perinatal period.

Sensori-motor synchronization (SMS) is the coordination of rhythmic movement with an external rhythm. It plays a central role in motor, cognitive, and social behavior. SMS is commonly studied in adults and in children from four years of age onward. Prior to this age, the ability has rarely been investigated due to a lack of available methods. The present paper reviews what is known about SMS in young children, infants, newborns, and fetuses. The review highlights fetal and infant perception of rhythm and cross modal perception of rhythm, fetal, and infant production of rhythm and cross modal production of rhythm, and the contexts in which production of rhythm can be observed in infants. A primary question is whether infants, even newborns, can modify their spontaneous rhythmical motor behavior in response to external rhythmical stimulation. Spontaneous sucking, crying, and leg movements have been studied in the presence or absence of rhythmical auditory stimulation. Findings suggest that the interaction between movement and sound is present at birth and that SMS can be observed in special conditions and within a narrow range of tempi, particularly near the infant's own spontaneous motor tempo. The discussion centers on the fundamental role of SMS in interaction and communication at the beginning of life.

Disrupted sensorimotor synchronization, but intact rhythm discrimination, in children treated for a cerebellar medulloblastoma.

The aim of this study was to investigate the temporal abilities of children treated by surgery for a malignant tumor in the cerebellum, both in the perception and the production of rhythm. Children with a diagnosed medulloblastoma and age-matched control children were tested in a rhythm discrimination task and a sensorimotor synchronization task. Their motor and cognitive capabilities were also assessed through a battery of age-adapted neuropsychological tests. The results did not show any significant difference in performance between groups for the discrimination task. On the contrary, children with cerebellar lesions produced longer and more variable inter-tap intervals (ITI) in their spontaneous motor tempo (SMT) than did the control children. However, the length and, to a lesser extent, the variability of their SMT decreased after a synchronization phase, when they had been instructed to tap in synchrony with a beep. During the synchronization task, the children with medulloblastoma succeeded to modify the length of their ITI in response to an auditory rhythm, although with better success when the inter-stimuli intervals (ISI) were shorter than when they were longer than the ITIs of their own SMT. Correlational analyses revealed that children's poorer synchronization performance was related to lower scores in neuropsychological tests assessing motor dexterity and processing speed.

Air stepping in response to optic flows that move Toward and Away from the neonate.

To shed further light on the perceptual regulation of newborn stepping, we compared neonatal air stepping in response to optic flows simulating forward or backward displacement with stepping forward on a surface. Twenty-two 3-day-olds performed four 60 s trials in which they stepped forward on a table (Tactile) or in the air in response to a pattern that moved toward (Toward) or away (Away) from them or was static (Static). Significantly more steps were taken in the Tactile and Toward conditions than the Static condition. The Away condition was intermediate to the other conditions. The knee joint activity across the entire trial was significantly greater in the Toward than the Away condition. Within-limb kinematics and between-limb coordination were very similar for steps taken in the air and on the table, particularly in the Toward and Tactile conditions. These findings highlight that visual and tactile stimulation can equally elicit neonatal stepping.

Time perception in children treated for a cerebellar medulloblastoma.

The aim of the present study was to investigate temporal abilities in children treated by surgery for a malignant tumor in the cerebellum. Children with a diagnosed medulloblastoma and age-paired control children were given a temporal discrimination task (bisection task) and a temporal reproduction task with two duration ranges, one shorter than 1s and the other longer than 4s. The motor and cognitive capacities of these children were also assessed by a battery of age-adapted neuropsychological tests. The results did not show any significant difference in performance between the children with or without cerebellar lesions in the temporal discrimination task. It was only in the temporal reproduction task that the children with cerebellar lesions reproduced longer and more variable durations than the other children, but only for the short stimulus durations (≤ 1 s). In addition, a hierarchical regression analysis revealed that the best predictor of variance in temporal performance was a significantly lower processing speed in children with cerebellar lesions in comparison to their controls. These results indicated that the major cause of deficits in temporal judgments in children with cerebellar lesions was due to their inability to reproduce accurately short temporal intervals in association with low processing speed, rather than to a specific deficit in the perception of time.

Temporal bisection in 4-month-old infants.

The present study was the first to investigate infants' ability to discriminate time using a bisection task that has been extensively used with animals and human adults. Infants aged 4 months were presented with two standard auditory signals, one short (S = 500 ms) and one long (L = 1,500 ms), and were trained either to look to the left after S and to the right after L, or vice versa. During the test phase, the infants were then presented with intermediate durations without reinforcement as well as the two reinforced standard durations, for which the reinforcement was either immediate or delayed of 3 s. The times spent by the infants looking to the right, left or away from the target after the stimulus duration were coded by two blind coders. The results revealed an orderly psychophysical function with the proportion of long responses increasing with signal duration. The point of subjective equality (Bisection Point) was closer to the geometric mean of the short and long standard duration than to their arithmetic mean. Modeling using the scalar timing models revealed that our infants had a relatively high sensitivity to time but that their temporal performance was affected by the fact that they made a large number of random responses. The development of the perception of time is discussed in the light of similarities and differences in temporal bisection performance between different species (rats and humans) and the different levels of development observed within a given species.

Neonatal stepping in relation to terrestrial optic flow.

This experiment examined whether newborn stepping, a primitive form of bipedal locomotion, could be modulated by optical flow. Forty-eight 3-day-old infants were exposed to optical flows that were projected onto a horizontal surface above which the infants were suspended. Significantly more air steps were elicited by exposure to a terrestrial optical flow specifying forward translation than by a rotating optical flow or a static optical pattern. Thus, a rudimentary coupling between optical flow and stepping is present at birth, suggesting a precocious capacity in the newborn to perceive and utilize visual information specifying self-motion. The findings may help the early diagnosis of infants with visual or visual-motor deficits and the development of visually based interventions for disabled infants.