Unimanual and Bimanual Simultaneous Fingertapping in Schoolchildren: Developmental Aspects and Hand Preference-related Asymmetries

Computerised analysis of finger tapping was performed in 233 normal 5- to 12-year-old children whose hand preference was assessed with six demonstration actions. Performance with both hands became more rapid with age when tapping unimanually or simultaneously in phase with two hands as quickly as possible. There were no differences between the sexes. Performance with both hands also acquired more tapping regularity with age during unimanual tapping, whereas only the left hand did so during bimanual tapping. There was no age effect on the dexterity (speed) difference between unimanually tapping hands, nor on the relative time lag and the degree of synchrony between the hands in bimanual tapping. The degree of synchrony, however, becomes more stable in older children. The more righthanded children are, the faster the right hand is in unimanual tapping, and the more the right hand is ahead of the left hand during bimanual tapping. However, there is a right shift for both of these variables which makes them poor predictors of hand preference. These results suggest that there is a strong bias towards the right hand in complete righthanders as well as--to a lesser extent--in all others, which might be connected to the leading role of the left hemisphere for the performance aspects of hand motor function under study.

Ontogenesis of laterality in 3- to 10-yr.-old children: increased unimanual independence grounded on improved bimanual motor function

Underlying sensorimotor factors, such as intermanual coupling, contributing to optimal laterality, long remain immature. Using the handmotor laterality blackboard, developmental change in symmetric bimanual motor function for 413 children in groups of 3 to 10 years of age shows synchronicity increased between groups 3 and 5 years of age; but between groups 5 and 7 years of age, given immature coupling, one hand may still disturb the movements of the other one. Between groups 7 and 9 years of age, the hands gradually stop disturbing each other and move independently and fluently. Changes in intermanual coupling with increasing unimanual independence represent expression of changing interhemispheric integration across groups. This promotes optimal laterality and task distribution between the hands. Maturation of the corpus callosum is inferred to be a factor in these ontogenetic changes which ultimately lead to optimal left hemisphere specialization for actions such as fluent writing.

Ontogenetic trends in gnostic hand function in 3- to 12-yr-old children

The intimate relation between the sensory and motor functions of the hands during object manipulation and exploratory touch, the well-known improvement in object handling and constructive performance in ontogenesis and the emergent laterality thereof, assume changes in morphognostic capabilities in children. In this study we tried to corroborate the hypothesis of Mesker that mature and lateralized finger-thumb opposition is preceded by a stage of two-sided manual form agnosia in preschool children, followed by acquisition of morphognosis of the fingers and, finally, the thumbs. This study examined the development of gnostic hand function in 290 children from 3 to 11 years of age who drew the outlines of a meaningless wooden object passively felt with each hand without visual control. Analysis showed a clear ontogenetic change across the two age groups of increasing morphognostic function: 48% of the 6-yr.-olds drew correctly what the fingers of both left and right hands had perceived (thumbs, 14%). Of the 11-yr.-olds 91% and 61% performed perfectly with the right and left hands, respectively. The fingers preceded the thumbs in reproduction by most children, and the correct reproduction by the left thumb precedes that of the right thumb. The ontogenesis of bimanual sensorimotor functioning is discussed in the light of cortical and callosal development.

Facial identity and facial emotions: speed, accuracy, and processing strategies in children and adults

As yet, nearly all studies in face and facial affect recognition typically provide only data on the accuracy of processing, invariably also in the absence of reference data on abstract information processing. In this study, accuracy and speed of abstract visuo-spatial processing, face recognition, and facial emotion recognition were investigated in normal school children (7-10 years) and adults (25+/-4 years). In the age range of 7-10 years, accuracy of facial processing hardly increased, while speed did substantially increase with age. Adults, however, were substantially more accurate and faster than children. Differences between facial and abstract information processing were related to type of processing strategy, that is, configural or holistic processing versus featural or piecemeal processing. Improvement in task performance with age is discussed in terms of an enhanced efficiency of the configural organization of facial knowledge (facial information processing tasks), together with a further increase in processing capacity (all tasks). The differential developmental course of speed and accuracy levels indicates that speed is a more sensitive measure when children get older. Moreover, it also suggests that speed of performance, in addition to accuracy, might be successfully used in the assessment of clinical deficits, as has recently been demonstrated in children with autistic disorders of social contact.

Children with non-verbal learning disabilities (NLD): coherence values in the resting state may reflect hypofunctional long distance connections in the right hemisphere

EEG intrahemispheric coherences (HCohs) in the resting state in twenty-four 4 Hz frequency windows between 1 and 51 Hz were studied in 18 children with "non-verbal learning disorder" (NLD) and compared to a group of 18 children with "verbal learning disorder" (VLD). New facts were found in the NLD group. These concern hemispheric balance, expressed as left minus right (L-R) homologous HCohs: 1a). In the high frequencies (25-51 HZ) the number of long-distance HCohs, higher in the right hemisphere (RH), is lower than HCohs, which are higher in the left hemisphere (LH). A reversed interhemispheric asymmetry is seen for short distance HCohs in that band. These asymmetries are not found in the VLD group, and the tendency is even reversed. 1b). In the low frequencies (1-27 Hz) all higher HCohs are more numerous in the RH, irrespective of interelectrode distance (IED). In these bands there are no NLD-VLD group differences; 2). In NLD there is a significant inverse relationship between IED and (L-R)HCoh values (designated as LRDif) in the high frequencies: the larger the IED, the higher the LRDif. In the lower frequencies there is no such tendency. In the VLD group these relationships were absent. These preliminary results suggest long distance gamma band hypoconnectivity in the RH of NLD children, in line with the hypothesis of an RH long distance connectivity problem in NLD. This may explain difficulties with mtermodal perception (gestalt function). Finally in the NLD group some gamma band interhemispheric (ICohs) over F7/F8 and T3/T4 were lower than in VLD children and some gamma band ICohs were higher in NLD compared to VLD over O1/O2. This is possibly connected with the cognitive differences subserved by these areas, i.e., language, respectively visuospatial function.

Disordered recognition of facial identity and emotions in three Asperger type autists

In this report we aim to explore severe deficits in facial affect recognition in three boys all of whom meet the criteria of Asperger's syndrome (AS), as well as overt prosopagnosia in one (B) and covert prosopagnosia in the remaining two (C and D). Subject B, with a familially-based talent of being highly gifted in physics and mathematics, showed no interest in people, a quasi complete lack of comprehension of emotions, and very poor emotional reactivity. The marked neuropsychological deficits were a moderate prosopagnosia and severely disordered recognition of facial emotions, gender and age. Expressive facial emotion, whole body psychomotor expression and speech prosody were quasi absent as well. In all three boys these facial processing deficits were more or less isolated, and general visuospatial functions, attention, formal language and scholastic performances were normal or even highly developed with the exception of deficient gestalt perception in B. We consider the deficient facial emotion perception as an important pathogenetic symptom for the autistic behaviour in the three boys. Prosopagnosia, the absent facial and bodily expression, and speech prosody were important but varying co-morbid disorders. The total clinical picture of non-verbal disordered communication is a complex of predominantly bilateral and/or right hemisphere cortical deficits. Moreover, in B, insensitivity to pain, smells, noises and internal bodily feelings suggested a more general emotional anaesthesia and/or a deficient means of expression. It is possible that a limbic component might be involved, thus making affective appreciation also deficient.

Development of ideomotor praxis representation

To create a short screening instrument to investigate the development of ideomotor praxis representation (IPR), 357 normally developing children between the ages of 2 1/2 and 9 1/2 years were investigated. The IPR screening consisted of six mimed actions which had to be performed on verbal request. The greatest change in the representational style is the transition from performing the action using the body as the object to performing with an imaginary object (i.e. symbolic representation). This transition suggests a development from a concrete and egocentric level of performance to an abstract and allocentric level. Before the age of 6 years differences are evident between self-directed and externally directed gestures. The level of symbolic representation has to be dissociated from the degree of motor precision, which shows hardly any improvement after 6 years of age. With the proposed model one may interpret the level of IPR in clinical practice. IPR screening is clinically relevant from the age of 4 1/2 years onwards.

EEG coherence changes during finger tapping in acallosal and normal children: a study of inter- and intrahemispheric connectivity

The EEG inter- and intrahemispheric coherences (ICoh and HCoh) in the theta, alpha and beta bands were studied in an acallosal group (ACCG) of five children and a normal group of 30 sex- and age-matched children (NG) during resting and tapping conditions. Being functionally deficient, tapping in the ACCG was characterized by increased intertap intervals and variability (in right-hand tapping) and by variability together with decreased synchronization (in bimanual tapping). In the ACCG, frontal, central and parietal ICohs were shown to be smaller, while temporal ICohs were larger under all conditions (see also Koeda, T., Knyazeva, M., Jonkman, J., Njiokiktjien, C., De Sonneville, L., Vildavsky, V., 1995. The resting EEG in acallosal children: compensatory left hemisphere mechanisms? Electroencephalogr. Clin. Neurophysiol. 95, 397-407). The effect was most pronounced in the EEG beta band. The sagittal HCohs, including fronto-central, fronto-parietal, and centro-parietal HCohs within both hemispheres, were larger in the ACCG, whereas temporal HCoh (fronto-temporal, centro-temporal, parieto-temporal and occipito-temporal) were smaller, suggesting rearrangement of intracortical activity associated with callosal agenesis. Tapping induced an increase in ICoh and HCoh between frontal, central and parietal areas in the NG, and weak enhancement only in the left temporal HCoh in the ACCG. The beta band, the most reactive band in the NG, was 'silent' in the ACCG, suggesting deviant cortical function during motor activity as well.

Relation of early neuromotor and cranial signs with neuropsychological outcome at 4 years

The persistence and predictive value at 3-5 years of age of three signs detected within the first 18 months of life were investigated: phasic stretch reflex in one or both gastrocnemius muscles, imbalance in passive axial tone with an excess of dorsal extension, and a ridge on the squamous sutures. Phasic stretch reflex and at least one of the other signs were found in 14 children during repeated assessments within the first 18 months. The progress of these children was compared with that of 14 matched controls who had repeatedly normal neurological assessments during the first 18 months in the same clinic in Paris. At the age 3-5 years all the children were then assessed blindly by the second author from a pediatric neurological viewpoint and by two psychologists and two psychomotor therapists as well. The parents of the affected children reported significantly more problems in motor/praxis skills, language development and attention. Abnormal neurological signs were also significantly more frequent than in the controls. Suboptimal cognition did not reach significance. The neurological inclusion criteria were still present at 3-5 years old in 86% (vs. respectively 100% and 93% during the first 18 months of life) of this small group of children, while the cranial suture sign was still present in only 28% (vs. 64%). Findings of these three signs during the first 18 months of life may help in predicting long-term neurobehavioral or long-term neuropsychological problems.

The EEG in acallosal children. Coherence values in the resting state: left hemisphere compensatory mechanism?

Resting EEG interhemispheric and intrahemispheric coherences (ICoh and HCoh) in the theta, alpha and beta bands were studied in 7 patients with agenesis of the corpus callosum (5 children, aged 10-14 years, and 2 adults) and 2 groups of sex- and age-matched normal children and adults (42 subjects). In patients the ICohs (F3/F4, C3/C4, P3/P4, O1/O2) were lower than in the normal sample. The ICoh decrease, corresponding with the completeness of commissural agenesis, showed the essential role of the corpus callosum in interhemispheric EEG synchronization. A remarkable new fact was found, namely lower right hemisphere HCoh in the acallosal patients in comparison to the normals, suggesting reduced connectivity of the right hemisphere. It is assumed that the deviant HCoh patterns in the patients, most pronounced in the beta band, are indicative of compensatory left hemisphere mechanisms, accounting for a specific brain plasticity phenomenon in acallosal subjects.

Methylphenidate and information processing. Part 1: Differentiation between responders and nonresponders; Part 2: Efficacy in responders

Part 1 of this study attempted to discriminate clinical responders and nonresponders to methylphenidate (MPH) on the basis of neuropsychological deficit profiles. Part 2 addressed the question to what extent MPH might ameliorate these deficits. Hyperactive clinical responders (n = 30) and nonresponders (n = 28) to MPH, were compared to normal controls (n = 27) on selective and sustained attention tasks and on conventional psychological and neurological measures. The responders took part in a randomized double-blind placebo-controlled crossover study. They ingested a placebo (PL) or MPH (0.3-0.6 mg/kg/day) during 4 weeks, and were then tested. After crossover, another period of 4 weeks was concluded by a second test series. Compared to controls, both responders and nonresponders showed attention deficits in encoding, memory search, and decision operations, as well as in focused and sustained attention, vigilance, and use of feedback. These deficits were the most severe in the responders. Anamnestic data, IQ scores, and neurological variables did not discriminate between groups. MPH selectively alleviates attention deficits. MPH did not affect divided attention, except for an increased accuracy of response organization. The drug, however, greatly improved focused and sustained attention, vigilance, impulsivity, and the behavioral adaptivity to feedback.

Callosal size in children with learning disabilities

The corpus callosum (CC), the main structure subserving hemispheric collaboration, that is necessary for efficient cognitive functioning, undergoes developmental processes such as axonal retraction and myelination. Callosal growth therefore is vulnerable for adverse events such as perinatal asphyxia, but there are also genetic and epigenetic factors that determine form and thickness. MRI scans of 110 children, either with specific learning disabilities (LD), i.e. dysphasia/dyslexia, or with several degrees of general LD, showed callosa that were highly variable in size. The callosal size corrected for brain size did not vary significantly according to the severity of the LD, although it tended to be smaller in severe LD, i.e. mental retardation. Callosal size varied however, due to the likely presence of genetic influences or of adverse perinatal events. Children with familial dysphasia/dyslexia, had a thicker CC, possibly reflecting a poorly understood neurodevelopmental mechanism that inhibits the establishment of cerebral dominance. LD children (all subgroups together) with perinatal adverse events had a smaller CC than the familial cases, suggesting CC damage. Despite a multitude of developmental factors influencing the final size, this study suggests that total callosal size, supposedly linked to interhemispheric function, may contribute to the pathophysiological mechanisms that give rise to LD.

Methylphenidate-induced changes in ADDH information processors

In a randomized double-blind placebo-controlled crossover study, 17 hyperactives, clinically considered as drug responders, were administered a battery of information processing tasks to assess the efficacy of methylphenidate. The investigation concentrated on sustained attention, and, following a linear stage model of information processing (divided and focused attention), encoding, filtering, selective set and response organization operations. Methylphenidate did not affect short-term memory or visual retention, baseline motor speed and encoding. Methylphenidate improved vigilance aspects of sustained attention. The drug did not improve filtering but did enhance selective set (target search) operations. The decline in speed and speed variability as a result of medication could not readily be explained in terms of response organization processes. An attempt was made to unite the experimental results through the concept of signal-response frequency.

[The Kleine-Levin syndrome]

Two boys, aged 12 and 13 years, showed relapsing periods of somnolence and excessive eating, starting after a viral illness. One of them also showed periodic disturbance of sexual impulse control. The symptomatic periods were followed by symptom-free intervals in a highly characteristic pattern. This gave the clue to the diagnosis Kleine-Levin syndrome. The cause of this syndrome is unknown, in some cases a relationship between infectious disease or traumatic brain damage has been postulated. A dysfunction of the hypothalamus and associated structures is suspected. The syndrome has a rather favourable prognosis. The symptoms can be relieved by amphetamines, methylphenidate and probably also by lithium carbonate.

Late sequelae of a non-optimal neonatal neurological condition in ERPs at the age of 11-13 years

In a longitudinal study a selective attention task was administered to 11-13-year-old children. During this task (employing a combined filter and selective-set paradigm), event-related brain potentials were recorded to study timing and morphology of early and late selection processes. Task performance was prospectively and retrospectively related to neurological optimality at birth and to flash-evoked potential correlates that were registered at the age of five. The results provided evidence that even after 13 years neonatal neurological suboptimality was reflected in task performance, both in reaction time and in electrophysiological data. Task load interacted with group classification according to optimality to the disadvantage of suboptimals. This implied that load demands differentiated between groups. The event-related brain potentials revealed the existence of a negative shift associated with memory load (search-related negativity) at Fz and Cz, and a positive deflection at Pz (P3b) associated with target detection. Cortical activity, expressed in terms of these deflections, appeared to be less pronounced for the suboptimal group.

[Dysphatic development: clinical importance and neurological background]

The timely treatment of children with developmental dysphasia is important in the prevention of subsequent learning and behaviour disorders. The pathophysiology of developmental dysphasia is complex and depends on age. In the preverbal and early verbal phase the severity of the clinical picture is determined by accompanying motor function pathology (simple motor function, dysarthria, general and oral dyspraxia) and by receptive pathology (hearing, and auditory perception). In the verbal period linguistic problems become more prominent (syntax, morphology, semantics and verbal memory), these problems might be accompanied by oral motor symptoms. The different developmental language syndromes become more apparent with time. After kindergarten age the oral motor and perceptual problems diminish, but the language disorders, that influence communication and scholastic learning, remain. In a small number of children without oral motor, perceptual and memory problems, there exists a 'bare or nuclear syndrome', a so called 'pure dysphasia', without other neurological signs. In these children there is perhaps a genetically determined developmental disorder on a restricted neuronal level (no brain damage!). In more than half of the patients this syndrome is accompanied by other neurological signs, predominantly pointing to the left cerebral hemisphere. Furthermore there can be signs from the right cerebral hemisphere, the corpus callosum and from the afferent fibers systems for auditory perception. The nature and causes of these disorders are extremely variable, so that one cannot speak of the neural substrate or the pathogenesis. The diagnosis and the treatment can optimally only be performed by an experienced team, the expertise of which has to penetrate into the school education system.

Malformation or damage of the corpus callosum? A clinical and MRI study

Anomalies of the corpus callosum (CC) in children can be subdivided into two main categories: Malformations (also known as dysgenesis) and damage to a previously well-formed callosum. Pre- or perinatally acquired damage may have a mainly vascular, obstructive or hypoxic-ischemic etiology, whereas endotoxins and exotoxins might also play a role. Early postnatally acquired CC damage in children is mostly of vascular or traumatic origin. In some instances the CC is thinned after chronic pressure (e.g. in hydrocephalics). Nineteen of fifty children with psychomotor retardation had CC anomalies, most of them suggestive of acquired damage. Mild forms of CC anomalies are visible with MRI, but might be missed with a CT-scan. Children with acquired CC anomalies have signs of supposed Interhemispheric Disconnection (ID), which is partly responsible for their clinical syndrome of mental and motor retardation. The likelihood of finding a CC anomaly in a child seems to be enhanced by the predictive use of neuropsychological tasks indicative for ID.

Postural responses evoked by sinusoidal galvanic stimulation of the labyrinth. Influence of head position

In 15 healthy subjects we studied body sway reactions to sinusoidal 0.3 Hz binaural bipolar galvanic current up to 2 mA under three conditions. With the head forward and eyes closed, there is only a periodic lateral displacement of the centre of gravity, following the stimulation with a phase lag. In two other conditions, the head turned to the left or to the right without trunk torsion, the direction of sway was modified in such a way that there were mainly anteroposterior movements. It is thought that this experiment shows the modulatory influence of neck afferents on the direction of vestibulospinal motor effects in man.

Familial porencephalic white matter disease in two generations

We report the pedigree of a family in which a mother and her two children, a boy and a girl, all suffer from a similar, though variably expressed cerebral disorder, seen on CT as uni- or bilateral cavities within the supratentorial white matter in communication with the ventricular system. Additional white matter hypodensity around the lateral ventricles without ventricular widening provides preliminary evidence of a primary disease of myelination, in the absence of histopathological confirmation. This is probably the first report of "porencephaly" which shows a pattern of autosomal dominant inheritance.

[Brain atrophy as an artifact in ACTH administration]

An 8-month-old infant was treated for infantile spasms with long acting corticotrophin 25 IU daily for 32 days. CT, done 2 weeks after the treatment was discontinued, suggested diffuse brain atrophy. Repeat CT one year later was only borderline abnormal. No shift in the skull circumference curve was noted. Comparison to the literature led to the conclusion that the reversible changes in CT were caused by ACTH. The nature of this phenomenon is discussed as well as the implications for CT-diagnosis. The question arises whether ACTH or corticosteroids might cause irreversible brain damage.

Predictive value of neonatal neurological examination for cerebral function in infancy

Five days after birth, 144 clinically normal infants were examined according to Prechtl's 'optimality' method. 118 were classified as neurologically optimal and 26 as sub-optimal. At the ages of 12, 22 and 36 months, parents' reports indicated differences in behaviour between the two groups; and at age 22 months observed behaviour and some neurological variables also differed. All the perceived differences were to the disadvantage of the sub-optimal group. There were more differences among the boys than among the girls, and the differences were not the same for the two sexes. The study shows that there can be subtle differences at a later age between children who at birth are neurologically optimal or sub-optimal but clinically normal.

Displacement of the body's centre of gravity at galvanic stimulation of the labyrinth

The work of classical authors has been resumed in this study. Using a statokinesimeter which records displacements of the centre of gravity, the reactions of the postural balance of the standing human subject on galvanic stimulation of the labyrinth were demonstrated in an objective and reproducible manner. Using a bipolar binaural electrode position, 80 healthy test subjects were submitted to 1.5 mA galvanic stimulation for 4 sec. For each electrode position, the anteroposterior and lateral movements were recorded simultaneously, with the eyes open and with the eyes closed. The results differ from the classical descriptions in that they show that the vestibulospinal reflex elicited in this manner, involves a composite movement of different characteristics for the lateral than for the anteroposterior direction. It was found that the visual apparatus inhibits only lateral displacements. It is suggested that clinical application of this method may be possible.