Goal-directed arm movements in children with fetal alcohol syndrome: a kinematic approach

Single leg hopping in children with fetal alcohol spectrum disorder: Dynamic postural stability and kinematics

BACKGROUND

This study compared dynamic postural stability (DPS) and lower limb kinematics during single leg hopping (SLH) performed by typically-developed children from urban and rural settings and children with Fetal Alcohol Spectrum Disorder (FASD) from a rural setting.

METHODS

Typically-developed nine-year-old children from an urban (n = 27) and rural setting (n = 14) (controls), and nine-year-old children with FASD from a rural setting (n = 14) (cases) performed SLH and landing on a pressure mat. Motion analysis systems described 1) Spatiotemporal and centre of pressure parameters (COP) and lower limb sagittal plane kinematics. Descriptive results are presented in median and ranges and differences between groups were determined by Kruskal-Wallis and Mann-Whitney U statistical tests. The level of significance was p < 0.05.

RESULTS

During hopping, the urban controls had longer stance and swing times (p < 0.001) than the rural groups. The urban controls remained in greater hip flexion compared to the case group (p = 0.02). The urban controls landed in more plantarflexion at initial foot contact (IFC) than the cases (p < 0.001) and the rural controls (p = 0.03). The rural groups landed with greater knee extension at IFC than the urban controls (cases p = 0.04; rural controls p < 0.001). During the landing motion, the urban controls moved into more hip flexion compared to the cases (p = 0.015) and the rural controls (p = 0.026). The cases displayed greater COP anteroposterior values during landing compared to both control groups, but the case group displayed the fastest time to stability.

CONCLUSION

The different hopping strategies observed provides an indication of the movement capabilities of these groups.

[Experimental approaches to the investigation of behavioral disorders associated with prenatal alcohol exposure]

Fetal alcohol spectrum disorders (FASD) is an umbrella term which covers a wide range of deficits in prenatal and postnatal growth, anatomy and CNS functions produced by prenatal alcohol exposure. The most severe form of FASD is fetal alcohol syndrome (FAS) characterized by additional specific craniofacial and brain malformations. Despite a high prevalence and extensive clinical studies, the fundamental mechanisms of FASD are still poorly understood. Thereby, experimental models, which allow better control for both socio-environmental and genetic factors, are critical to our understanding of FASD. The review is focused on the effects of exposure to alcohol during the prenatal period in animal models. The authors outline that prenatally alcohol-induced changes in motor and executive functions, learning and memory, stress reactivity and affective state are remarkably parallel between animals and humans. Finally, the authors consider a potential impact of postnatal social and environmental factors on the outcome in experimental models of FASD.

The postural stability of children with foetal alcohol spectrum disorders during one-leg stance: A feasibility study

Background

Postural control may be impaired in children with foetal alcohol spectrum disorders (FASD). The study assessed the protocol feasibility in terms of (1) recruiting children with FASD in a rural, small town; (2) using the measurement instruments in a real-life setting; (3) the one-leg standing (OLS) task and (4) presenting preliminary results on postural stability of children with and without FASD.

Methods

Nine-year-old children diagnosed with and without FASD were invited to participate. Twenty-eight children performed OLS. Feasibility outcomes included recruitment, measurement instrument use and task instruction. Postural stability outcomes included standing duration, centre of pressure (COP) and body segment acceleration.

Results

Participants recruitment was feasible in terms of the (1) ability to sample a reasonable participant number in a rural town setting and the capacity to increase the sample size if more schools are included in the sampling frame and (2) use of assent and consent forms that were appropriate for this population. The measurement instruments were user-friendly, cost-effective and time-efficient. Instructions for the task require amendment to address foot placement of the non-weight–bearing leg. There was a significant difference between cases and controls on mean COP velocity (p = 0.001) and the pelvis segment acceleration in the mediolateral direction (p = 0.01) and the anteroposterior direction (p = 0.027). The control children took longer to achieve postural control. The girls demonstrated a significant difference for the COP anteroposterior displacement (p = 0.008) and velocity (p = 0.049).

Conclusions

The recruitment of children with and without FASD in a rural, small town and the administration of measurement instruments in a real-life, school-based setting was feasible. However, the verbal instructions for the task require revision. The male control group took longer to achieve postural control because the task was performed differently between the two groups. However, the case girls were slower to achieve postural control than control girls though performing the task similarly.

Developmental progression and side specialization in upper-limb movements from 4 to 8 years in children born preterm and fullterm

This study investigated developmental changes and differences in upper-limb movement organization from 4 to 8 years of age in children born preterm (PT) and fullterm (FT). Kinematic recordings of precision-demanding unimanual movements and lateral assessments were carried out in 37 children (18 PT). All children, particularly children born PT, displayed considerable gain in movement kinematics. Contrary to controls, children born PT displayed persistently less-evident side preference. Gestational age (GA) contributed significantly to kinematic differences shown, with larger upper-limb deviances in the lowest GAs, in agreement with cross-sectional findings of altered hemispheric connections and delayed side-specialization among children born very PT.

An automated approach for measuring infant head orientation in a face-to-face interaction

Head orientation in face-to-face interactions between mothers and infants is an important component of their communicative processes. Manual coding, however, is laborious. Obtaining inter-observer reliability is difficult, with disagreements mostly being related to the on- and offsets of a limited number of orientation categories. We used a motion capture system and developed an automated method for the quantitative measurement of infant head orientation in mother--infant face-to-face-interactions. Automated motion capture systems have the potential to objectively document not only the on- and offset of behaviors, but also continuous changes. Infants wore a cap with three reflecting markers, and eight infrared cameras captured the positions of the markers. Analytic algorithms generated continuous three-dimensional descriptions of the infants' head movements. We report here on an initial feasibility study of four infants. To evaluate the effectiveness of the automated approach, we compared it to standard manual categorical coding of six infant head orientations. We found that the central reliability issue was disagreement at the boundaries of the coding categories identified by continuous automated coding versus manual coding. The automated method was both more feasible and more precise in capturing continuous small changes. The study provides evidence for the usefulness of automated measurement of infant head orientation when infants interact in relational space.

The Use of Open- and Closed-Loop Control During Goal-Directed Force Responses by Children with Heavy Prenatal Alcohol Exposure

BACKGROUND

Many daily functional activities involve goal-directed responses based on open-loop and closed-loop motor control, yet little is known about how children with heavy prenatal alcohol exposure organize and regulate these 2 types of control systems when completing a goal-directed force response.

METHODS

Children with (n = 19) or without (n = 23) heavy prenatal alcohol exposure were required to match a target force (25 and 50% of maximum voluntary force) in a specified target time (200, 800, and 2,000 ms). Target force and produced force were visually displayed on a computer monitor. The analog force-time record was parsed into 2 segments: the period beginning from force initiation to the first reversal in force was designated the open-loop phase, and the remainder of the response was the closed-loop phase.

RESULTS

Compared to controls, alcohol-exposed children produced a significantly shorter duration of open-loop control, a higher open-loop phase rate of force development, a shorter time to reach maximum force during the closed-loop phase, and greater absolute target force error. Increasing target force magnitude did not differentially alter the performance of the clinical group.

CONCLUSIONS

The results indicate that alcohol-exposed children experience deficits in completing goal-directed force responses that likely stem from an alcohol-related insult to the central nervous system. Therapeutic exercises should be designed to recalibrate internal timing systems and improve visuomotor integration.

Fetal alcohol spectrum disorders

Prenatal alcohol exposure (PAE) is one of the most prevalent and modifiable risk factors for somatic, behavioral, and neurological abnormalities. Affected individuals exhibit a wide range of such features referred to as fetal alcohol spectrum disorders (FASD). These are characterized by a more or less specific pattern of minor facial dysmorphic features, growth deficiency and central nervous system symptoms. Nevertheless, whereas the diagnosis of the full-blown fetal alcohol syndrome does not pose a major challenge, only a tentative diagnosis of FASD can be reached if only mild features are present and/or maternal alcohol consumption during pregnancy cannot be verified. The respective disorders have lifelong implications. The teratogenic mechanisms induced by PAE can lead to various additional somatic findings and structural abnormalities of cerebrum and cerebellum. At the functional level, cognition, motor coordination, attention, language development, executive functions, memory, social perception and emotion processing are impaired to a variable extent. The long-term development is characterized by disruption and failure in many domains; an age-adequate independency is frequently not achieved. In addition to primary prevention, individual therapeutic interventions and tertiary prevention are warranted; provision of extensive education to affected subjects and their caregivers is crucial. Protective environments are often required to prevent negative consequences such as delinquency, indebtedness or experience of physical/sexual abuse.

Long-term influences of a preterm birth on movement organization and side specialization in children at 4-8 years of age

This study explored upper-limb and head kinematics during unimanual goal-directed movements in children born preterm (PT) and full-term (FT) aged 4-8 years. Further, functional lateralization was investigated through side-specific kinematics and hand preference observations. Altogether, 141 children were included, divided into three sub-groups based on gestation week at birth (GW). Children born FT (38-41 GW) and moderately PT (33-35 GW) showed faster, smoother, and shorter movement trajectories than children born very PT (V-PT < 33 GW). Only children born FT expressed evident side differences that were characterized by smoother movements with the preferred side. Regarding hand preference, the children born V-PT showed increased rates of non-right-handedness compared with the other groups. Regardless of hand preference, the children born V-PT showed less well organized movements compared with the other groups. These findings suggest that spatio-temporal movement organization and side specialization at pre-/early school-age are affected by a PT birth, and more frequently so for children born before 33 GWs, indicating long-lasting influences on neuromotor development and specialization.

Neurobehavioral, neurologic, and neuroimaging characteristics of fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can have deleterious consequences for the fetus, including changes in central nervous system development leading to permanent neurologic alterations and cognitive and behavioral deficits. Individuals affected by prenatal alcohol exposure, including those with and without fetal alcohol syndrome, are identified under the umbrella of fetal alcohol spectrum disorders (FASD). While studies of humans and animal models confirm that even low to moderate levels of exposure can have detrimental effects, critical doses of such exposure have yet to be specified and the most clinically significant and consistent consequences occur following heavy exposure. These consequences are pervasive, devastating, and can result in long-term dysfunction. This chapter summarizes the neurobehavioral, neurologic, and neuroimaging characteristics of FASD, focusing primarily on clinical research of individuals with histories of heavy prenatal alcohol exposure, although studies of lower levels of exposure, particularly prospective, longitudinal studies, will be discussed where relevant.

A comparison of the different animal models of fetal alcohol spectrum disorders and their use in studying complex behaviors

Prenatal ethanol exposure (PNEE) has been linked to widespread impairments in brain structure and function. There are a number of animal models that are used to study the structural and functional deficits caused by PNEE, including, but not limited to invertebrates, fish, rodents, and non-human primates. Animal models enable a researcher to control important variables such as the route of ethanol administration, as well as the timing, frequency and amount of ethanol exposure. Each animal model and system of exposure has its place, depending on the research question being undertaken. In this review, we will examine the different routes of ethanol administration and the various animal models of fetal alcohol spectrum disorders (FASD) that are commonly used in research, emphasizing their strengths and limitations. We will also present an up-to-date summary on the effects of prenatal/neonatal ethanol exposure on behavior across the lifespan, focusing on learning and memory, olfaction, social, executive, and motor functions. Special emphasis will be placed where the various animal models best represent deficits observed in the human condition and offer a viable test bed to examine potential therapeutics for human beings with FASD.

Relations among upper-limb movement organization and cognitive function at school age in children born preterm

OBJECTIVE

To explore relations between aspects of upper-body spatiotemporal movement organization and intelligence in children born preterm at school age.

METHODS

Three-dimensional (3D) kinematic recordings of arm and head movements during a unimanual precision task were related to performance on the Wechsler Intelligence Scale for Children, 4th edition, in a sample of 32 children born preterm (gestational age, mean: 31.5 weeks [range: 22-35 weeks]; birth weight, mean: 1699 g [range: 404-2962 g]) at 6 years to 8 years with no diagnosed cognitive, sensory, or motor impairments compared with 40 age-matched control children born fullterm.

RESULTS

In the children born preterm, upper-limb movement duration and segmentation of movement trajectories were significantly associated with full-scale intelligence quotient independent of gestational age (GA) and sex. These effects pertained to the preferred side, characterized by more effective movement organization being linked with increased intelligence scores. The same relations were not seen in the controls. Within the children born preterm, a significant effect of GA was also found for some aspects of upper-limb movement organization. Full-scale intelligence quotient was within normal limits for both groups but significantly lower in the preterm (mean: 94.5 [range: 72-120]) compared with the fullterm (mean: 101.7 [range: 76-119]) born children.

CONCLUSIONS

The findings demonstrate that, independent of GA, the spatiotemporal organization of upper-limb movements is partly associated with cognitive performance in children born preterm.

Children with heavy prenatal alcohol exposure experience reduced control of isotonic force

BACKGROUND

Heavy prenatal alcohol exposure can result in diverse and extensive damage to the central nervous system, including the cerebellum, basal ganglia, and cerebral cortex. Given that these brain regions are involved in the generation and maintenance of motor force, we predicted that prenatal alcohol exposure would adversely affect this parameter of motor control. We previously reported that children with gestational alcohol exposure experience significant deficits in regulating isometric (i.e., constant) force. The purpose of this study was to determine whether these children exhibit similar deficits when producing isotonic (i.e., graded) force.

METHODS

Children with heavy prenatal alcohol exposure and typically developing children completed a series of isotonic force contractions by exerting force on a load cell to match a criterion target force displayed on a computer monitor. Two levels of target force (5 or 20% of maximum voluntary force) were investigated in combination with varying levels of visual feedback.

RESULTS

Compared with control children, children with heavy prenatal alcohol exposure generated isotonic force signals that were less accurate, more variable, and less complex in the time domain. Specifically, interactions were found between group and visual feedback for response accuracy and signal complexity, suggesting that these children have greater difficulty altering their motor output when visual feedback is low.

CONCLUSIONS

These data suggest that prenatal alcohol exposure produces deficits in regulating isotonic force, which presumably result from alcohol-related damage to developing brain regions involved in motor control. These children will most likely experience difficulty performing basic motor skills and daily functional skills that require coordination of finely graded force. Therapeutic strategies designed to increase feedback and, consequently, facilitate visual-motor integration could improve isotonic force production in these children.

Long-term alterations of striatal parvalbumin interneurons in a rat model of early exposure to alcohol

Background

Exposure to alcohol in utero is a known cause of mental retardation. Although a certain degree of motor impairment is always associated with fetal alcohol spectrum disorder, little is known about the neurobiological basis of the defective motor control. We have studied the striatal interneurons containing parvalbumin in a rat model of fetal alcohol spectrum disorder.

Methods

Newborn rats received ethanol by inhalation from postnatal day two through six and parvalbumin striatal neurons were labeled by immunohistochemistry on postnatal day 60. The spatial distribution of parvalbumin interneurons was studied using Voronoi spatial tessellation and their dendritic trees were completely reconstructed.

Results

Parvalbumin interneurons of ethanol-treated animals showed a clustered spatial distribution similar to that observed in control animals. The dendritic tree of parvalbumin interneurons was significantly reduced in ethanol-treated animals, as compared with controls.

Conclusions

Striatal parvalbumin interneurons are crucial components of the brain network serving motor control. Therefore, the shrinkage of their dendrites could contribute to the motor and cognitive symptoms observed in fetal alcohol spectrum disorder.

Fetal alcohol spectrum disorders: neuropsychological and behavioral features

Heavy prenatal alcohol exposure can cause alterations to the developing brain. The resulting neurobehavioral deficits seen following this exposure are wide-ranging and potentially devastating and, therefore, are of significant concern to individuals, families, communities, and society. These effects occur on a continuum, and qualitatively similar neuropsychological and behavioral features are seen across the spectrum of effect. The term fetal alcohol spectrum disorders (FASD) has been used to emphasize the continuous nature of the outcomes of prenatal alcohol exposure, with fetal alcohol syndrome (FAS) representing one point on the spectrum. This paper will provide a comprehensive review of the neuropsychological and behavioral effects of heavy prenatal alcohol exposure, including a discussion of the emerging neurobehavioral profile. Supporting studies of lower levels of exposure, brain-behavior associations, and animal model systems will be included when appropriate.

Selective underexpression of Kv3.2 and Kv3.4 channels in the cortex of rats exposed to ethanol during early postnatal life

The expression of voltage-gated potassium channels belonging to the Kv3 family has been studied in the sensori-motor cortex of rats exposed to alcohol inhalation during the first postnatal week (P2-P6). The study was carried out using comparative RT-PCR. At P9, a significant reduction of the expression of Kv3.2 and Kv3.4 subunits occurred in alcohol-treated animals, as compared with controls. The expression of the Kv3.4a splicing variant, which is thought to be critically involved in the high-frequency firing of some cortical interneurons, was also correspondingly reduced. The downregulation of Kv3.2 and Kv3.4a subunits represented a long-lasting effect of alcohol exposure, since it was also observed in P24 animals. The expression of both Kv3.1 and Kv3.3 channels appeared to be not significantly affected by alcohol exposure. An increased susceptibility to apoptotic neuronal death after early postnatal exposure to ethanol was confirmed by the lower bcl-2/bax ratio observed in alcohol-treated animals. Although Kv3.4 subunits are thought to trigger apoptosis, the lack of upregulation in our model argues against their involvement in the mechanism leading to alcohol-induced apoptosis. The possible consequences of the selective downregulation of Kv3 subunits on the cortical function, as well as their relevance for the genesis of fetal alcohol effects, are discussed.