Louise Rönnqvist

Preparation for grasping an object: A developmental study.

The development of visually controlled grasping actions was studied in two experiments. An optoelectronic technique (SELSPOT) was used to monitor the opening and closing of the hand during reaching actions by measuring the change in the distance between thumb and index finger. The purpose of Experiment 1 was to establish an adult criterion for the development. It was shown that adults started closing the hand around the target well before touch and that the timing was dependent on the size of the target. The hand started to close earlier when grasping a small rather than a large target. In addition, the degree of hand opening was also less for a small than for a large target. In Experiment 2 it was shown that infants who were 5-6, 9, and 13 months of age also controlled their grasping actions visually and started closing the hand around the target in anticipation of the encounter rather than as a reaction to the encounter. However, the strategy of the two younger age groups was different from that of adults. They started closing the hand closer to the time of contact with the target than did the 13-month-olds, who were comparable to adults in this respect. The timing was not dependent on the size of the target in any of the infant groups. In all age groups, reaching and grasping were most commonly organized in a continuous way; that is, the hand started to close without any interruption in the approach. The opening of the hand was found to be adjusted to target size in the 9- and 13-month-olds but not in the 5-6 month olds.

Vision of the hand and environmental context in human prehension

Abstract.Previous findings on the role of visual contact with the hand in the control of reaching and grasping have been contradictory. Some studies have shown that such contact is largely irrelevant, while more recent ones have emphasised its importance. In contrast, information arising from the surrounding environment has received relatively little attention in the study of prehensile actions. In order to identify the roles of both sources of information, we made kinematic comparisons between three conditions. In the first, reaching was performed in a dimly lit room and compared with a second condition in which reaches in the dark, but with the thumb and first finger illuminated, were made to a luminous object. This contrast allows the effects of environmental context to be identified. A comparison between the second and a third condition, in which both vision of the hand and the environment was removed, but the object was still visually available, enabled the assessment of how and when vision of the hand plays a role. Removing environmental cues had effects both early and late in the reach, while vision of the hand was only crucial in the period after peak deceleration. In addition, removal of both sources of information resulted in larger grip apertures. Differences and similarities between our findings and those of other studies are discussed, as is the ongoing debate about the relative importance of visual feedback of the hand in the control and co-ordination of prehensile actions. We conclude with suggestions for further research based on the set-up used in the present study.

Impairment Severity Selectively Affects the Control of Proximal and Distal Components of Reaching Movements in Children with Hemiplegic Cerebral Palsy.

This study explored proximal‐to‐distal components during goal‐directed reaching movements in children with mild or moderate hemiplegic cerebral palsy (HCP); [seven females, four males; mean age 8y 6mo; SD 27mo], compared with age‐matched, typically developing children (seven females, five males; mean age 8y 3mo [SD 25mo]. Severity of HCP was assessed following the approach of Claeys et al. Optoelectronic registrations were made during unimanual reaching‐to‐grasp and reaching‐to‐hit movements with both the affected/non‐preferred and unaffected/preferred side. Regardless of task, the children with HCP, particularly those with moderate impairment, displayed less optimal spatiotemporal organization of movements performed with the affected arm. Compared with the goal to hit, and increasingly with more severe impairment, children with HCP adapted to the goal to grasp by recruiting augmented shoulder movements when reaching with the affected side. A resulting impact on distal kinematics was found in shorter, straighter, and less segmented movement paths. Thus, depending on severity of hemispheric lesions and task complexity, unilateral brain injuries in HCP may selectively affect neural pathways underlying both proximal and distal arm movement control. Levels of both ipsi‐ and contralateral activation in relation to side and lesion severity should be considered in future studies on prehension movements in HCP.

Lateral biases in head turning and the moro response in the human newborn: Are they both vestibular in origin?

Head turning after release from the midline and the Moro response to a full-body drop in 15 full-term newborns lying supine on a custom-built platform was studied. While the lateral bias for head turning was not as pronounced as for the Moro response, it was still assumed in the ratio of 2 (right):1 (left) as predicted by Previc (1991). Onset latency and time-to-peak acceleration were both significantly shorter in the right arm during the initial phase of the Moro response. For both measures, this right arm bias persisted over four consecutive elicitations in most infants. Vaginally delivered infants and those born by Caesarean section did not differ in terms of head preference and the two measures of arm advantage. Our main finding was that infants with a right-sided head preference had a consistently shorter onset latency for the right arm. We interpret this association as stemming from a common labyrinthine asymmetry that involves different vestibulospinal pathways for the neck and arm muscles. In general, our findings are discussed in the context of Prevics (1991) left-otolithic dominance hypothesis and Grattan, De Vos, Levy, and McClintocks (1992) model of newborn functional asymmetries.

A critical examination of the Moro response in newborn infants—Symmetry, state relation, underlying mechanisms

The primary purpose of the present study was to analyze quantitatively the vestibular evoked Moro response, and the symmetry of the movement pattern involved, as the traditional descriptions bring about. Another aim was to determine the segmental movements involved and determine whether the components of the Moro response are dependent on changes in the infants behavioral state. Another question concerns whether the form of these movements changed over repeated trials on the same day, or from the first to the fifth day after birth. Vestibular evoked Moro responses of 52 neonates, 1-5 days of age, elicited in different behavior states (State 1-5), were examined and quantitatively analyzed. The response was evoked by a predefined, rapid, downward, vertical body motion, without any dorsiflexion of the infants head. Optoelectronic device (SELSPOT II) were used to monitor the arm/hand movement patterns involved in the response. The three-dimensional movement pattern in space, duration, velocity, latency, and the acceleration of both arms/hands were analyzed in relation to the infants behavioral state. The response movements were structured into phases of abduction/extension, adduction/flexion and the extension/flexion of the fingers. The vestibular stimulation used was found to be sufficient for eliciting an adequate Moro response. The segmental movement pattern of the Moro response was found to be sensitive to the infants behavioral state at the time when the response was elicited. This was found in the movement pattern, duration, latency, and the velocity of the response. The response was found to be asymmetrical, in 82% of the infants it was found to be a predominant shorter onset latency of the right arm, in 12% the opposite was found. These findings suggest that there is a fundamental, spinal asymmetry involved in the Moro response which is subject to supraspinal influences emanating from the vestibulospinal system. No differences were found between 1 and 5 days of age for any of the scoring categories, and no differences were found within groups over six successive trials.

Handedness in preterm born children: A systematic review and a meta-analysis

It has been proposed that left and/or non-right handedness (NRH) is over-represented in children with a history of preterm birth because such births are associated with a greater incidence of insult to the brain. We report an approximate two-fold increase in left and/or non-right handedness based on a systematic search of the literature from 1980 to September 2010 for English-language articles reporting handedness status in preterm children compared with fullterm controls either as a main focus of the study or as a secondary finding. In total, thirty articles met the inclusion criteria. However, there was a great variation between the included studies in terms of objectives, population characteristics, sample size and methodologies used. While the majority of studies reported a higher incidence of NRH in preterm than fullterm children, this was not a consistent finding. A quality assessment was made to explore the differences in overall study quality and handedness assessment methodology between studies. A random-effects model meta-analysis was then performed to estimate the accumulated effect of preterm birth on handedness (18 studies; 1947 cases and 8170 controls). Preterm children displayed a significantly higher occurrence of NRH than fullterm children (odds ratio [OR]: 2.12; 95% confidence interval [CI]: 1.59-2.78). Sources of heterogeneity were investigated by supplementary meta-analyses considering studies with high or low overall and handedness assessment quality. Publication bias was assessed by Eggers test of the intercept and Duvall and Tweedies trim-and-fill method. The outcomes of these procedures did not jeopardize the overall finding of reliably increased OR for NRH in preterm children. The present review suggests that a preterm birth is indeed associated with a greater than two-fold likelihood of NRH. Several studies also explored the relationship between handedness and neuropsychological functioning (cognition mainly) with an array of methods. Although not without disagreement, this association was found to be concordant. Studying handedness in preterm children, therefore, is a potentially important index of hemispheric organization and cognitive and sensory-motor functions following neurodevelopmental disturbance.

Explicit versus implicit social cognition testing in autism spectrum disorder

Although autism spectrum disorder is defined by reciprocal social-communication impairments, several studies have found no evidence for altered social cognition test performance. This study examined explicit (i.e. prompted) and implicit (i.e. spontaneous) variants of social cognition testing in autism spectrum disorder. A sample of 19 adolescents with autism spectrum disorder and 19 carefully matched typically developing controls completed the Dewey Story Test. ‘Explicit’ (multiple-choice answering format) and ‘implicit’ (free interview) measures of social cognition were obtained. Autism spectrum disorder participants did not differ from controls regarding explicit social cognition performance. However, the autism spectrum disorder group performed more poorly than controls on implicit social cognition performance in terms of spontaneous perspective taking and social awareness. Findings suggest that social cognition alterations in autism spectrum disorder are primarily implicit in nature and that an apparent absence of social cognition difficulties on certain tests using rather explicit testing formats does not necessarily mean social cognition typicality in autism spectrum disorder.

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

Background:  Although many studies have documented deficits in general motor functioning in children with fetal alcohol syndrome (FAS), few have employed detailed measurements to explore the specific nature of such disabilities. This pilot study explores whether three‐dimensional (3D) kinematic analysis may generate increased knowledge of the effect of intrauterine alcohol exposure on motor control processes by detecting atypical upper‐limb movement pattern specificity in children with FAS relative to typically developing (TD) children.

Functional asymmetries in the stepping response of the human newborn: a kinematic approach

In order to investigate subtle expressions of functional asymmetries in newborn leg movements, kinematic registrations were made on a sample of 40 healthy fullterm newborn infants during performance of the stepping response. Time–position data were collected from markers attached to the hip, knee and ankle joints of the left and right leg, and movements of both legs recorded simultaneously. Findings included evident side differences in terms of smoother trajectories of the right leg as a consequence of less movement segmentation compared to the left leg. Additionally, analyses of intralimb coordination revealed side differences with regard to stronger ankle–knee couplings and smaller phase shifts in the right leg. The findings suggest that asymmetries in newborn stepping responses are present in terms of spatio-temporal parameters and intralimb coordination. No evidence of a lateral preference in terms of frequency of the first foot moved was found. The present study adds new understanding to the lateralized attributes of the stepping response in the human newborn and as such points to new directions of research on the nature of laterality in the future.

Training of goal directed arm movements with motion interactive video games in children with cerebral palsy – A kinematic evaluation

Abstract Objective: The main aim of this study was to evaluate the quality of goal-directed arm movements in 15 children with cerebral palsy (CP) following four weeks of home-based training with motion interactive video games. A further aim was to investigate the applicability and characteristics of kinematic parameters in a virtual context in comparison to a physical context. Method: Kinematics and kinetics were captured while the children performed arm movements directed towards both virtual and physical targets. Results: The children’s movement precision improved, their centre of pressure paths decreased, as did the variability in maximal shoulder angles when reaching for virtual objects. Transfer to a situation with physical targets was mainly indicated by increased movement smoothness. Conclusion: Training with motion interactive games seems to improve arm motor control in children with CP. The results highlight the importance of considering both the context and the task itself when investigating kinematic parameters.