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IMPORTANCE: Cerebral palsy (CP) is the most common childhood physical disability. Early intervention for children younger than 2 years with or at risk of CP is critical. Now that an evidence-based guideline for early accurate diagnosis of CP exists, there is a need to summarize effective, CP-specific early intervention and conduct new trials that harness plasticity to improve function and increase participation. Our recommendations apply primarily to children at high risk of CP or with a diagnosis of CP, aged 0 to 2 years. OBJECTIVE: To systematically review the best available evidence about CP-specific early interventions across 9 domains promoting motor function, cognitive skills, communication, eating and drinking, vision, sleep, managing muscle tone, musculoskeletal health, and parental support. EVIDENCE REVIEW: The literature was systematically searched for the best available evidence for intervention for children aged 0 to 2 years at high risk of or with CP. Databases included CINAHL, Cochrane, Embase, MEDLINE, PsycInfo, and Scopus. Systematic reviews and randomized clinical trials (RCTs) were appraised by A Measurement Tool to Assess Systematic Reviews (AMSTAR) or Cochrane Risk of Bias tools. Recommendations were formed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework and reported according to the Appraisal of Guidelines, Research, and Evaluation (AGREE) II instrument. FINDINGS: Sixteen systematic reviews and 27 RCTs met inclusion criteria. Quality varied. Three best-practice principles were supported for the 9 domains: (1) immediate referral for intervention after a diagnosis of high risk of CP, (2) building parental capacity for attachment, and (3) parental goal-setting at the commencement of intervention. Twenty-eight recommendations (24 for and 4 against) specific to the 9 domains are supported with key evidence: motor function (4 recommendations), cognitive skills (2), communication (7), eating and drinking (2), vision (4), sleep (7), tone (1), musculoskeletal health (2), and parent support (5). CONCLUSIONS AND RELEVANCE: When a child meets the criteria of high risk of CP, intervention should start as soon as possible. Parents want an early diagnosis and treatment and support implementation as soon as possible. Early intervention builds on a critical developmental time for plasticity of developing systems. Referrals for intervention across the 9 domains should be specific as per recommendations in this guideline.

IMPORTANCE: Cerebral palsy describes the most common physical disability in childhood and occurs in 1 in 500 live births. Historically, the diagnosis has been made between age 12 and 24 months but now can be made before 6 months’ corrected age. OBJECTIVES: To systematically review best available evidence for early, accurate diagnosis of cerebral palsy and to summarize best available evidence about cerebral palsy–specific early intervention that should follow early diagnosis to optimize neuroplasticity and function. EVIDENCE REVIEW: This study systematically searched the literature about early diagnosis of cerebral palsy in MEDLINE (1956-2016), EMBASE (1980-2016), CINAHL (1983-2016), and the Cochrane Library (1988-2016) and by hand searching. Search terms included cerebral palsy, diagnosis, detection, prediction, identification, predictive validity, accuracy, sensitivity, and specificity. The study included systematic reviews with or without meta-analyses, criteria of diagnostic accuracy, and evidence-based clinical guidelines. Findings are reported according to the PRISMA statement, and recommendations are reported according to the Appraisal of Guidelines, Research and Evaluation (AGREE) II instrument. FINDINGS: Six systematic reviews and 2 evidence-based clinical guidelines met inclusion criteria. All included articles had high methodological Quality Assessment of Diagnostic Accuracy Studies (QUADAS) ratings. In infants, clinical signs and symptoms of cerebral palsy emerge and evolve before age 2 years; therefore, a combination of standardized tools should be used to predict risk in conjunction with clinical history. Before 5 months’ corrected age, the most predictive tools for detecting risk are term-age magnetic resonance imaging (86%-89% sensitivity), the Prechtl Qualitative Assessment of General Movements (98% sensitivity), and the Hammersmith Infant Neurological Examination (90% sensitivity). After 5 months’ corrected age, the most predictive tools for detecting risk are magnetic resonance imaging (86%-89% sensitivity) (where safe and feasible), the Hammersmith Infant Neurological Examination (90% sensitivity), and the Developmental Assessment of Young Children (83% C index). Topography and severity of cerebral palsy are more difficult to ascertain in infancy, and magnetic resonance imaging and the Hammersmith Infant Neurological Examination may be helpful in assisting clinical decisions. In high-income countries, 2 in 3 individuals with cerebral palsy will walk, 3 in 4 will talk, and 1 in 2 will have normal intelligence. CONCLUSIONS AND RELEVANCE: Early diagnosis begins with a medical history and involves using neuroimaging, standardized neurological, and standardized motor assessments that indicate congruent abnormal findings indicative of cerebral palsy. Clinicians should understand the importance of prompt referral to diagnostic-specific early intervention to optimize infant motor and cognitive plasticity, prevent secondary complications, and enhance caregiver well-being.

We used functional magnetic resonance imaging (fMRI) to identify brain areas involved in auditory rhythm perception. Participants listened to three rhythm sequences that varied in temporal predictability. The most predictable sequence was an isochronous rhythm sequence of a single interval (ISO). The other two sequences had nine intervals with unequal durations. One of these had interval durations of integer ratios relative to the shortest interval (METRIC). The other had interval durations of non-integer ratios relative to the shortest interval (NON-METRIC), and was thus perceptually more complex than the other two. In addition, we presented unpredictable sequences with randomly distributed intervals (RAN). We tested two hypotheses. Firstly, that areas involved in motor timing control would also process the temporal predictability of sensory cues. Therefore, there was no active task included in the experiment that could influence the participant perception or induce motor preparation. We found that dorsal premotor cortex (PMD), SMA, preSMA, and lateral cerebellum were more active when participants listen to rhythm sequences compared to random sequences. The activity pattern in supplementary motor area (SMA) and preSMA suggested a modulation dependent on sequence predictability, strongly suggesting a role in temporal sensory prediction. Secondly, we hypothesized that the more complex the rhythm sequence, the more it would engage short-term memory processes of the prefrontal cortex. We found that the superior prefrontal cortex was more active when listening to METRIC and NON-METRIC compared to ISO. We argue that the complexity of rhythm sequences is an important factor in modulating activity in many of the rhythm areas. However, the difference in complexity of our stimuli should be regarded as continuous.

Evidence suggests that dopamine regulation of motor activity undergoes postnatal maturation. To examine the role of the dopamine 1 receptor (D1R)/dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) signaling pathway for this maturation, we studied the effects of a D1R agonist on motor activity in weanling and adult wild-type (WT) mice and mice that lack DARPP-32, a key messenger in the D1R signaling pathway. Locomotor activity was not affected by D1R activation in WT weanling mice but was significantly stimulated in WT adult mice. This stimulation was absent in DARPP-32 (−/−) adult mice. In contrast, the inhibitory effects that were observed on rearing activity in WT weanling and adult mice were present in DARPP-32 (−/−) mice. DARPP-32 plays a key role for development of D1R motor stimulatory effects.

Evidence suggests that dopamine regulation of motor activity undergoes postnatal maturation. To examine the role of the dopamine 1 receptor (D1R)/dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) signaling pathway for this maturation, we studied the effects of a D1R agonist on motor activity in weanling and adult wild-type (WT) mice and mice that lack DARPP-32, a key messenger in the D1R signaling pathway. Locomotor activity was not affected by D1R activation in WT weanling mice but was significantly stimulated in WT adult mice. This stimulation was absent in DARPP-32 (-/-) adult mice. In contrast, the inhibitory effects that were observed on rearing activity in WT weanling and adult mice were present in DARPP-32 (-/-) mice. DARPP-32 plays a key role for development of D1R motor stimulatory effects.

Preterm birth frequently involves white matter injury and affects long-term neurologic and cognitive outcomes. Diffusion tensor imaging has been used to show that the white matter microstructure of newborn, preterm children is compromised in a regionally specific manner. However, until now it was not clear whether these lesions would persist and be detectible on long-term follow-up. Hence, we collected diffusion tensor imaging data on a 1.5-T scanner, and computed fractional anisotropy and coherence measures to compare the white matter integrity of children born preterm to that of control subjects. The subjects for the preterm group (10.9 ± 0.29 y; n9; birth weight ≤ 1500 g; mean gestational age, 28.6 ± 1.05 wk) possessed attention deficits, a common problem in preterms. They were compared with age- and sex-matched control children (10.8 ± 0.33 y; n10; birth weight ≥ 2500; gestational age, ≥ 37 wk). We found that the preterm group had lower fractional anisotropy values in the posterior corpus callosum and bilaterally in the internal capsules. In the posterior corpus callosum this difference in fractional anisotropy values may partially be related to a difference in white matter volume between the groups. An analysis of the coherence measure failed to indicate a group difference in the axonal organization. These results are in agreement with previous diffusion tensor imaging findings in newborn preterm children, and indicate that ex-preterm children with attention deficits have white matter disturbances that are not compensated for or repaired before 11 y of age.

Preterm birth frequently involves white matter injury and affects long-term neurologic and cognitive outcomes. Diffusion tensor imaging has been used to show that the white matter microstructure of newborn, preterm children is compromised in a regionally specific manner. However, until now it was not clear whether these lesions would persist and be detectible on long-term follow-up. Hence, we collected diffusion tensor imaging data on a 1.5-T scanner, and computed fractional anisotropy and coherence measures to compare the white matter integrity of children born preterm to that of control subjects. The subjects for the preterm group (10.9 ± 0.29 y; n = 9; birth weight = 1500 g; mean gestational age, 28.6 ± 1.05 wk) possessed attention deficits, a common problem in preterms. They were compared with age- and sex-matched control children (10.8 ± 0.33 y; n = 10; birth weight = 2500; gestational age, = 37 wk). We found that the preterm group had lower fractional anisotropy values in the posterior corpus callosum and bilaterally in the internal capsules. In the posterior corpus callosum this difference in fractional anisotropy values may partially be related to a difference in white matter volume between the groups. An analysis of the coherence measure failed to indicate a group difference in the axonal organization. These results are in agreement with previous diffusion tensor imaging findings in newborn preterm children, and indicate that ex-preterm children with attention deficits have white matter disturbances that are not compensated for or repaired before 11 y of age.

Without practice, bimanual movements can typically be performed either in phase or in antiphase. Complex temporal coordination, e.g., during movements at different frequencies with a noninteger ratio (polyrhythms), requires training. Here, we investigate the organization of the neural control systems for in-phase, antiphase, and polyrhythmic coordination using functional magnetic resonance imaging (fMRI). Brisk rhythmic tapping with the index fingers was used as a model behavior. We demonstrate different patterns of brain activity during in-phase and antiphase coordination. In-phase coordination was characterized by activation of the right anterior cerebellum and cingulate motor area (CMA). Antiphase coordination was accompanied by extensive fronto-parieto-temporal activations, including the supplementary motor area (SMA), the preSMA, and the bilateral inferior parietal gyri, premotor cortex, and superior temporal gyri. When contrasting polyrhythmic tapping with in-phase tapping, activity was seen in the same set of brain regions, and in the posterior cerebellum and the CMA. Antiphase and polyrhythmic coordination may thus to a large extent use common neural control circuitry. In a separate experiment, we analyzed the neural control of the rhythmic structure and the serial order of finger movements during polyrhythmic tapping. Polyrhythmic tapping was compared with an isochronous coordination pattern that retained the same serial order of finger movements as the polyrhythm. This experiment showed that the preSMA and the bilateral superior temporal gyri may be crucial for the rhythmic control of polyrhythmic tapping, while the cerebellum, the CMA, and the premotor cortices presumably are more involved in the ordinal control of the sequence of finger movements.

In a population‐based follow‐up study (the Stockholm Neonatal Project), 182 children with a birth weight of 1500g or less (very‐low birth weight: VLBW) and a control group of 125 children born healthy at term were examined with the Wechsler Preschool and Primary Scale of Intelligence‐Revised (WPPSI‐R) and a neuropsychological test battery (Nepsy) at 5½ years of age. The WPPSI‐R results of the VLBW children fell well within the normal range: WPPSI‐R full‐scale IQ 95.7, verbal subscale IQ 99.9, and performance subscale IQ 91.6. Nevertheless, the control group had significantly better results than the VLBW group which could be attributed to the greater variability of the VLBW group, with a larger proportion falling in the lower area of the IQ distribution, especially on the performance subscale. Likewise, the control group displayed better executive function (Nepsy). Paternal education was equal in the two groups and was the single most important predictor of IQ, possibly acting as a protective factor. The need for glasses or lenses was inversely associated with all IQ measures and severe retinopathy of prematurity (ROP) had the most negative impact on full‐scale and performance IQ. These two IQ measures were also negatively associated with intrauterine growth retardation late in pregnancy. We conclude that VLBW children, in the absence of these identified risk factors, have normal cognitive development.

The present study addressed the question whether the deviant postural adjustments in children with spastic diplegia can be attributed to their crouched sitting position or primarily to their neural deficit. Postural adjustments during sitting in an erect and in a crouched position on a movable platform were assessed in 10 children, aged 3 to 7years 6 months, with mild‐to‐severe forms of spastic diplegia and 10 age‐ and sex‐matched control children. Multiple surface EMGs of neck, trunk, and leg muscles and kinematics of head, body sway, and pelvis were recorded during forward and backward translations. The children with normal motor development showed a distinct adaptation of postural adjustments to sitting position. The children with cerebral palsy (CP) had a deficient adaptational capacity which was more pronounced in the erect than in the crouched position. Thus, the crouched sitting position did not induce postural deficiency but seemed to offer a solution to the sensory‐motor problem of the instability experienced. Children with severe diplegia exhibited a lack of direction specificity in the leg muscles during backward body sway, which points to a basic deficit in postural control. In addition, these children showed marked dysfunctions in the precise tuning of the postural adjustments to task‐specific conditions. In the children with mild‐to‐moderate forms of CP the basic level of control was intact.

The present study addressed the question whether the deviant postural adjustments in children with spastic diplegia can be attributed to their crouched sitting position or primarily to their neural deficit. Postural adjustments during sitting in an erect and in a crouched position on a movable platform were assessed in 10 children, aged 3 to 7 years 6 months, with mild-to-severe forms of spastic diplegia and 10 age- and sex-matched control children. Multiple surface EMGs of neck, trunk, and leg muscles and kinematics of head, body sway, and pelvis were recorded during forward and backward translations. The children with normal motor development showed a distinct adaptation of postural adjustments to sitting position. The children with cerebral palsy (CP) had a deficient adaptational capacity which was more pronounced in the erect than in the crouched position. Thus, the crouched sitting position did not induce postural deficiency but seemed to offer a solution to the sensory–motor problem of the instability experienced. Children with severe diplegia exhibited a lack of direction specificity in the leg muscles during backward body sway, which points to a basic deficit in postural control. In addition, these children showed marked dysfunctions in the precise tuning of the postural adjustments to task-specific conditions. In the children with mild-to-moderate forms of CP the basic level of control was intact.

Recent functional magnetic resonance imaging (fMRI) studies suggest that the control of fingertip forces between the index finger and the thumb (precision grips) is dependent on bilateral frontal and parietal regions in addition to the primary motor cortex contralateral to the grasping hand. Here we use fMRI to examine the hypothesis that some of the areas of the brain associated with precision grips are more strongly engaged when subjects generate small grip forces than when they employ large grip forces. Subjects grasped a stationary object using a precision grip and employed a small force (3.8 N) that was representative of the forces that are typically used when manipulating small objects with precision grips in everyday situations or a large force (16.6 N) that represents a somewhat excessive force compared with normal everyday usage. Both force conditions involved the generation of time-variant static and dynamic grip forces under isometric conditions guided by auditory and tactile cues. The main finding was that we observed stronger activity in the bilateral cortex lining the inferior part of the precentral sulcus (area 44/ventral premotor cortex), the rostral cingulate motor area, and the right intraparietal cortex when subjects applied a small force in comparison to when they generated a larger force. This observation suggests that secondary sensorimotor related areas in the frontal and parietal lobes play an important role in the control of fine precision grip forces in the range typically used for the manipulation of small objects.

Functional magnetic resonance imaging experiments were performed in human motor cortex at 1.5 T by sampling two successive gradient recalled echo images in a single shot. Several aspects of brain mapping methods based on T2*‐weighted imaging and R2*mapping were quantitatively compared. These include the detected activation volume, functional contrast (FC), signal‐to‐noise ratio (SNR), and contrast‐to‐noise ratio (CNR). Studies based on the R2*mapping method have the following potential advantages: maximum functional contrast, less dependent on TE; and reduced inflow effects. R2*mapping produced the highest functional contrast, but not the largest activation volume due to the reduced signal‐to‐noise ratio and inflow effects. The sensitivity for activation detection is significantly correlated with the contrast‐to‐noise ratio, which is determined by both the SNR and FC. Copyright © 2001 John Wiley & Sons, Ltd.Abbreviations used:BOLDblood oxygen level dependentCNRcontrast‐to‐noise ratioFCfunctional contrastFFTfast fourier transformationGREgradient recalled echoROIregion of interestSNRSignal‐to‐noise ratioTEecho time.

Functional magnetic resonance imaging experiments were performed in human motor cortex at 1.5 T by sampling two successive gradient recalled echo images in a single shot. Several aspects of brain mapping methods based on T2^*-weighted imaging and R2^* mapping were quantitatively compared. These include the detected activation volume, functional contrast (FC), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Studies based on the R2^* mapping method have the following potential advantages: maximum functional contrast, less dependent on TE; and reduced inflow effects. R2^* mapping produced the highest functional contrast, but not the largest activation volume due to the reduced signal-to-noise ratio and inflow effects. The sensitivity for activation detection is significantly correlated with the contrast-to-noise ratio, which is determined by both the SNR and FC. Copyright © 2001 John Wiley & Sons, Ltd. Abbreviations used: BOLD blood oxygen level dependent CNR contrast-to-noise ratio FC functional contrast FFT fast fourier transformation GRE gradient recalled echo ROI region of interest SNR Signal-to-noise ratio TE echo time.

Mirror movements in individuals with hemiplegic cerebral palsy (CP) may result from a reorganization of the central sensorimotor system. Motor performances of both hands were measured to characterize mirror activity (or mirroring) and hand functions in 22 participants (6 to 18 years) with hemiplegic CP and in 17 control participants. During a unimanual repetitive squeezing task, contractions of the active hand and fingertip forces of the opposite hand were recorded simultaneously. In the control group, slight mirror activity (or mirroring) was found that decreased with age. In participants with CP, mirror activity was 15 times stronger than in the control group, and was found at all age levels. Mirroring was more prominent in the unaffected hand of the CP group. The amount of mirror activity was not related to the degree of hemiplegia, which was assessed with measures of spasticity, strength, and dexterity. Mirror movements disturbed functional bimanual skills, although to some extent they could be suppressed by voluntary effort.

The aim was to investigate the performance of children with attention‐deficit‐hyperactivity disorder (ADHD) in tasks involving motor‐memory representations. A special grip object recorded forces generated by the fingertips during a precision grip‐lift task. Common objects were lifted from a linear scale. Twenty‐five boys with ADHD were evaluated and grouped according to the presence (ADHD+) or absence (ADHD) of movement dysfunction using the Movement Assessment Battery for Children (Henderson and Sugden 1992). Mean group ages were 11.4 years(range 9.0 to 11.0 years) and 11.7 years (9.0 to 15.6 years), respectively. They were compared to a control group of 25 age‐matched boys, mean group age 11.8 years(range 9.0 to 13.0 years). Variability of motor performance was predominant in the ADHD+ group. Several of these participants presented a higher grip‐force output during the gripping movement. They also had difficulties in adapting the motor output to target different weights, suggesting deficient anticipatory parameter control based on memory representations. The results suggest that in some children motor problems are due to detrimental neural control functions rather than core symptoms of ADHD.

Between 1987 and 1998, 470 patients visited the national clinic for obstetrical brachial plexus palsies at the Karolinska Hospital, Stockholm, Sweden. This study reports on 247 children examined at 5 years of age using a special protocol for testing the sensory and motor function of the hand. The children were distributed in various groups depending on the number of injured nerves, whether they had some muscle activity in their biceps or deltoid muscles at 3 months of age, and whether any operations with nerve reconstruction had been performed. The shoulder range of movement in C5–6 palsies was significantly better in the group which had been operated on (operated group), but otherwise there were no differences between children who had been operated on (non‐operated group) and those who had not. A decrease in grip strength and bimanual function in level C5–6 palsies was found, though these roots should not innervate the distal hand. Outcome was not influenced by the number of avulsions in upper‐plexus palsies or whether the operation took place before or after the age of 6 months. The group with extensive lesions (C5‐Th1) had the most root avulsions, showing a correlation between increased avulsions and decreased hand function. This study does not support operating on children with no activity of the biceps and deltoid muscles at 3 months of age, as other authors have concluded. Rather, it favours waiting for a late recovery.

In previous studies of fingertip forces during precision grip in subjects with Parkinson's disease (PD), we observed regular oscillations in isometric force. The present study characterizes the nature of these oscillations. Fingertip forces were recorded from the index finger and thumb during precision grip‐lifts with a 300 g and 900 g object in 10 subjects with PD and 20 healthy control subjects. Fourier analysis confirmed that all subjects with PD exhibited force oscillations with a clearly definable frequency (∼7–11 Hz). Five of these subjects also exhibited a second lower frequency peak (∼5 Hz). Approximately half of the 20 control subjects displayed a single frequency peak (∼8–12 Hz), which was generally lower in amplitude than in the subjects with PD (representing enhanced physiological tremor), whereas the remaining control subjects had low‐amplitude, broad‐based spectra (representing physiological tremor). The amplitude of the force oscillations was higher for lifts with the heavier object in both the control subjects and subjects with PD. l‐Dopa resulted in a decreased tremor amplitude but did not influence the frequency. The force oscillations of the two opposing digits normal to the grip surfaces were in phase, whereas the oscillations tangential to the grip surfaces were often out of phase. The results suggest that the multipeaked force rate trajectories reported previously are caused by action tremor. The similarity of force oscillations in subjects with PD and healthy control subjects suggests common tremor‐generating mechanisms and supports the notion that the parkinsonian action tremor (AT) is an exaggerated form of physiological tremor. These findings provide insight into the impaired hand function observed in individuals with PD.

Most manual grips can be divided in precision and power grips on the basis of phylogenetic and functional considerations. We used functional magnetic resonance imaging to compare human brain activity during force production by the right hand when subjects used a precision grip and a power grip. During the precision-grip task, subjects applied fine grip forces between the tips of the index finger and the thumb. During the power-grip task, subjects squeezed a cylindrical object using all digits in a palmar opposition grasp. The activity recorded in the primary sensory and motor cortex contralateral to the operating hand was higher when the power grip was applied than when subjects applied force with a precision grip. In contrast, the activity in the ipsilateral ventral premotor area, the rostral cingulate motor area, and at several locations in the posterior parietal and prefrontal cortices was stronger while making the precision grip than during the power grip. The power grip was associated predominately with contralateral left-sided activity, whereas the precision-grip task involved extensive activations in both hemispheres. Thus our findings indicate that in addition to the primary motor cortex, premotor and parietal areas are important for control of fingertip forces during precision grip. Moreover, the ipsilateral hemisphere appears to be strongly engaged in the control of precision-grip tasks performed with the right hand.

Functional magnetic resonance imaging (fMRI) based on multiple-echo T2* mapping has attracted much attention recently. The contrasts in the parametric T2* maps are usually too low to allow direct image registration. In this study, an image registration strategy has been proposed for single-shot multi-echo data sets acquired for dynamic T2* mapping. We performed image registration of the T2*-weighted images before the calculation of the T2* parameter maps using two different strategies. One is to perform separate image registration on each echo and the other is to use the same motion correction parameters extracted from the second echo for all the data. Both strategies increase the number of activated voxels and reduce the effective noise level. The results also indicate that, for a single-shot dual-echo image data set, it is slightly preferable to use the second echo for direct image registration and then apply the same motion correction parameters to the first echo images. J. Magn. Reson Imaging 1999;10:154–158. © 1999 Wiley-Liss, Inc.

Functional magnetic resonance imaging (fMRI) based on multiple‐echo T2* mapping has attracted much attention recently. The contrasts in the parametric T2* maps are usually too low to allow direct image registration. In this study, an image registration strategy has been proposed for single‐shot multi‐echo data sets acquired for dynamic T2* mapping. We performed image registration of the T2*‐weighted images before the calculation of the T2* parameter maps using two different strategies. One is to perform separate image registration on each echo and the other is to use the same motion correction parameters extracted from the second echo for all the data. Both strategies increase the number of activated voxels and reduce the effective noise level. The results also indicate that, for a single‐shot dual‐echo image data set, it is slightly preferable to use the second echo for direct image registration and then apply the same motion correction parameters to the first echo images. J. Magn. Reson Imaging 1999;10:154–158. © 1999 Wiley‐Liss, Inc.

This study examined phonological working memory and speech discrimination among children with attention‐deficit–hyperactivity disorder (ADHD) with and without motor problems. Forty‐one children were assigned to three groups; children with ADHD (N=9), children with ADHD plus developmental coordination disorder (ADHD+, N=13), and age‐matched control children (N=19). The subjects’ability to classify stimulus pairs was examined in two experiments. The first experiment required subjects to discriminate pairs of monosyllabic stimuli with contrasting consonants to test speech discrimination without using a working‐memory load. In the second protocol, subjects were exposed to two‐ to five‐syllabic non‐word pairs with contrasting vowels in order to test speech discrimination with a working‐memory load. The subjects classified the pairs as being either the same or different in both experiments. No significant differences were found between the subject groups in the discrimination task with monosyllables. When exposed to the two‐ to five‐syllabic stimuli, the ADHD+ group scored significantly lower than both other groups. This was attributed to a higher sensitivity to working‐memory load. Some possible explanations of this effect are discussed.

Children with spastic hemiplegia have impaired dexterity in the affected extremity. The purpose of the present study was to investigate whether the force co-ordination pattern during precision grip in 13 children between 4 and 10 years of age with predominant unilateral brain lesions is related to manual dexterity and to the location and size of the brain lesion. The force co-ordination pattern was investigated by means of a specially designed object that monitored the isometric fingertip forces applied to the contact surfaces during precision grip. Hand function was measured by means of neurological examination, functional hand-grips and dexterity. Brain lesions were identified by series of ultrasound and MRI scans. Normally, the fingertip forces are applied to the object in the initial phase of the lift in an invariant force co-ordination pattern (i.e. grip–lift synergy), in which the grip and load forces are initiated simultaneously and increase in parallel with unimodal force rate trajectories. A majority of children with unilateral brain lesions had not developed the force co-ordination pattern typical for their age, but produced an immature or a pathological pattern. The developmental level of the grip–lift synergy was determined and quantified according to criteria derived from earlier studies on normally developed children. There was a clear relationship between the developmental level of the grip–lift synergy and impaired dexterity, indicating that proper development of the force co-ordination pattern is important for skilled hand function. The grip–lift synergy correlated with the total extent of lesions in the contralateral cortex and white matter and with lesions in the thalamus/basal ganglia, while no correlation was found for isolated cortical lesions. The results suggest that the neural circuits involved in the control of the precision grip are organized in a parallel and distributed system in the hemispheres, and that the basal ganglia are important during the formation of these circuits. Perinatal lesions in specific cortical motor areas may be compensated for by circuits elsewhere in the grip–lift motor system, while large lesions exclude this possibility.

This study examined phonological working memory and speech discrimination among children with attention-deficit–hyperactivity disorder (ADHD) with and without motor problems. Forty-one children were assigned to three groups; children with ADHD (N=9), children with ADHD plus developmental coordination disorder (ADHD+, N=13), and age-matched control children (N=19). The subjects' ability to classify stimulus pairs was examined in two experiments. The first experiment required subjects to discriminate pairs of monosyllabic stimuli with contrasting consonants to test speech discrimination without using a working-memory load. In the second protocol, subjects were exposed to two- to five-syllabic non-word pairs with contrasting vowels in order to test speech discrimination with a working-memory load. The subjects classified the pairs as being either the same or different in both experiments. No significant differences were found between the subject groups in the discrimination task with monosyllables. When exposed to the two- to five-syllabic stimuli, the ADHD+ group scored significantly lower than both other groups. This was attributed to a higher sensitivity to working-memory load. Some possible explanations of this effect are discussed.

It has been possible to expand considerably our understanding of human motor development by making a detailed analysis of various types of movement and muscular activation patterns during different stages of development. Alterations in development subsequent to the appearance of brain lesions have enabled valuable information to be collected about the underlying neural mechanisms, in addition to new information concerning the pathophysiology of cerebral palsy. Studies on the development of the corticospinal system indicate that plastic changes can take place after perinatal brain damage.

This study examined whether postural responses emerge in children in a predetermined way before independent sitting is achieved, and in what respect postural responses in infants differ from those in adults. Children just able to sit independently and children not yet able to sit were exposed to surface perturbations (translation and rotation) while body movement and electromyographic (EMG) responses were recorded. Perturbations causing a backward sway of the body (i.e., forward translation and legs-up rotation), elicited consistent patterns of muscle activity in ventral hip, trunk, and neck muscles in the independently sitting children. A high tonic EMG background activity in trunk and neck extensor muscles was inhibited at the onset of the ventral muscle activity. Kinematic analysis revealed that backward rotation of the pelvis was the first detectable body movement, while head movements (linear and angular displacement) were irregular and occurred later than the pelvis movement. Perturbations in the opposite direction, causing a forward sway, evoked variable responses in dorsal trunk and neck muscles, suggesting that the excitability level for postural responses was set according to the stability limits of the body. Children not yet able to sit without support were tested when the support around the waist, given by the experimenter's hands, was released prior to the onset of the platform perturbation. Postural responses were elicited in ventral muscles following a backward sway in all children and in about 60% of all trials. Often, only some of the ventral muscles were activated. No distinct responses were evoked during perturbations imposing a forward sway. These results suggest that (1) backward rotation of the pelvis triggers the postural adjustments in the independently sitting children; (2) a basic form of the postural adjustment develops in a predetermined manner before children practice independent sitting; and (3) the basic structure of ventral muscle activation pattern resembles that of adults, while the activation of the dorsal muscles (inhibition) differs in several aspects. These findings are in agreement with a recent model of central pattern generators for postural responses consisting of two operative levels. At the first level, which is triggered by backward rotation of the pelvis, the basic activation pattern is generated. At the second level, the pattern is shaped and fine-tuned by multisensory interactions from all activated sensory systems. The basic pattern present in the youngest infants may be produced mainly by neural networks at the first level, while the shaping function develops during practice, the shaping function being subjected to a learning process in which appropriate responses are formed in conjunction with the establishment of an internal neural representation for sitting.

In a previous study we found that subjects with Parkinson's disease (PD) had an impaired capability to initiate and sequence successive movement phases during lifts of small objects using the precision grip, and that they had regular oscillations in the force rates. The present study examined whether these subjects could use anticipatory control, in which the force output is scaled prior to liftoff, based on the object's physical properties. Subjects lifted an instrumented test object between the tips of the thumb and index finger while the employed grip force, load force (vertical lifting force), and corresponding time derivatives were recorded. In the first experiment, the object's weight was varied to assess its influence on the isometric force output. Subjects with PD scaled the isometric force increase according to the object's weight. In another experiment, the weight changed in proportion to the volume to determine whether subjects could make associative transformations between visual size information and the weight of the object. Subjects with PD still scaled the forces toward the expected weight, proportional to the volume of the object. Finally, programmed adjustments in force to sudden self-induced load changes were examined while subjects dropped a disk with one hand into a plate attached to the bottom of the grip instrument, held with the other hand. Subjects with PD had preparatory increases in the grip force prior to the disk contact, which matched the change in load, though may have been more dependent on visual feedback. We conclude that subjects with PD are capable of using anticipatory control to parameterize the isometric force output during a familiar lifting task.

When an object held by a precision grip is subjected to an abrupt vertical load perturbation, somatosensory input from the digits triggers an increase in grip force to restore an adequate safety margin, preventing frictional slips. In adults the response occurs after a latency of 60–80 ms. In the present study, children from 2 years old upward and adults grasped and lifted an object using a precision grip. Sudden, unpredicted increases in load force (tangential to the grip surfaces) were induced by the experimenter by dropping a small disc on to a receptacle attached to the object. The impact elicited a grip force response which in young children had a longer latency and a smaller amplitude than was seen in adults. The grip response latency gradually become shorter and its amplitude increased with increasing age, reaching adult values at 6–10 years. The muscle activity underlying the response could have several bursts. The adults showed one brisk response, appearing 40–50 ms after impact, in extrinsic and intrinsic hand muscles, while younger children also exhibited a short-latency burst, appearing about 20 ms after impact. It is suggested that the short-latency response was mediated via spinal pathways, and that these pathways are disengaged by supraspinal centers during development. In a predictable loading situation, when subjects dropped the disc themselves into the receptacle using the contralateral hand, they changed strategy. Adults induced a well-timed anticipatory grip force increase prior to the impact that was scaled to the weight of the object. The youngest children did not time the force increase properly in relation to the impact. Yet, they could scale their anticipatory grip force increase with respect to the weight of the dropped disc. This suggests a well-developed capacity to use information about the weight of objects held by one hand to parameterize a programmed force output to the other hand.

The coordination of manipulative forces was examined in 10 subjects with Parkinson's disease (PD) both OFF and ON medication while they grasped and lifted a small object using the precision grip. The development of grip (squeeze) force and load (vertical lifting) force was recorded and compared to a group of age-matched control subjects. Subjects with PD often exhibited a prolonged delay between the first digit contact with the object and initiation of the lifting drive. These subjects also exhibited stepwise increases in force, with regular oscillations in the force rates. However, once the vertical drive began, the main increase in grip and load force generally was in parallel and most other temporal aspects of the force coordination were similar to those of the control subjects. The extent to which the movement initiation was delayed was related to the stage of the disease, and most subjects improved ON medication. When the object was held in the air, subjects with PD used a grip force level which was similar to that of the control subjects, and all subjects adjusted their grip force according to the surface texture. Furthermore, they exhibited proper reflexive corrections to sudden changes in load (object perturbations), suggesting intact sensorimotor integration. We conclude that the most obvious impairments in the coordination of this task were delayed initiation of the grip–lift sequence and tremor-like oscillations superimposed on otherwise normal force.