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1.
Neuroreport ; 10(16): 3405-10, 1999 Nov 08.
Article in English | MEDLINE | ID: mdl-10599853

ABSTRACT

The P300 event-related potential (ERP) was studied at the beginning, in the middle, and at the end of an auditory stimulus discrimination task in 70 normal 9-year-old children. Easily distractible children showed frontally a short-latency P300 response to target stimuli throughout the task, whereas in the non-distractible children the corresponding response was distinctly smaller and also showed a tendency to decrease in size towards the end of the task. The short-latency frontal P300 response reflects activation of the brain's orienting networks, and it normally decreases in size when stimuli lose their 'novelty value' with stimulus repetition. Persistent frontal P300 suggest that distractible children continued to show enhanced orienting to stimuli that should have already been well encoded and/or categorized.


Subject(s)
Attention Deficit Disorder with Hyperactivity/physiopathology , Auditory Perception/physiology , Event-Related Potentials, P300/physiology , Acoustic Stimulation , Brain Mapping , Child , Female , Frontal Lobe/physiology , Humans , Male
2.
Neuroreport ; 10(9): 1869-74, 1999 Jun 23.
Article in English | MEDLINE | ID: mdl-10501523

ABSTRACT

Event-related potentials were recorded in response to intermittently presented, non-attended trains of identical auditory stimuli in healthy 9-year-old children. In abnormally distractible children (n =24), the first tone in each train elicited a significantly larger N1 vertex response than in the non-distractible children (n 24), suggesting that increased distractibility may be associated with an abnormally strong cerebral orienting towards non-attended stimuli. A later negativity at around 300 ms, which increases in amplitude with stimulus repetition and may thus reflect the building up of a functional neuronal representation of the stimulus properties, was significantly smaller in the distractible than in the non-distractible children. These findings demonstrate that event-related potential measures may be useful in helping to understand the information processing found in distractible children.


Subject(s)
Attention Deficit Disorder with Hyperactivity/physiopathology , Attention/physiology , Evoked Potentials, Auditory/physiology , Orientation/physiology , Acoustic Stimulation , Brain Mapping , Cerebral Cortex/physiology , Child , Female , Habituation, Psychophysiologic/physiology , Humans , Male
3.
Dev Med Child Neurol ; 40(6): 380-7, 1998 Jun.
Article in English | MEDLINE | ID: mdl-9652779

ABSTRACT

Speech and language comprehension and production were assessed at the age of 5 years in a cohort of children born preterm at < or = 32 weeks' gestational age (N=55) in comparison with children born at term and of similar age, sex, and social backgrounds. Data both including and excluding major neurological disabilities are presented. Mean performance for the entire group of preterm children was significantly lower than for the controls on most of the measures including the composite IQ scores. When the nine children who had major neurological disabilities were excluded from the preterm group, statistically significant differences were found on four of the total 12 speech and language measures. Intellectually normal preterm children without major neurological disability were slower than the controls on rapid word retrieval. In addition, difficulties in comprehending relative concepts were typical for the preterm children. The results suggest 'subtle dysnomia', which is indicative of later reading problems. On global verbal measures and on the basic speech and language aspects the study groups did not differ. Specific language impairment, defined as a discrepancy of > 1SD between Performance IQ and Verbal IQ scores, showed a tendency to be more common in the control group. Within both the study groups, the boys showed a tendency for a greater discrepancy between their Performance and Verbal IQ scores.


Subject(s)
Infant, Premature , Language Development , Speech Disorders , Child, Preschool , Cohort Studies , Female , Follow-Up Studies , Humans , Intelligence , Male
4.
Dev Med Child Neurol ; 40(1): 21-30, 1998 Jan.
Article in English | MEDLINE | ID: mdl-9459213

ABSTRACT

Forty-six intellectually normal children born preterm (< or =32 weeks of gestation) without major neurological disabilities and a control group of term children matched for age, sex, and parental educational and occupational status were assessed at the age of 5 years using neuropsychological tests emphasizing perceptual and visuomotor functions. The results show that in terms of cognitive functions these preterm children are a very heterogenous group, but many of them still have problems in visuospatial and sensorimotor functions. The preterm children achieved lower mean scores in tests where coordination and voluntary control of hands in combination with tactile, kinaesthetic, and visuospatial perception were needed. They had most difficulty with drawing directions of lines and in integrating two or more forms. They also had problems with 3-dimensional constructions as well as visual perception of rotated shapes or slopes of lines.


Subject(s)
Cognition , Psychomotor Performance , Space Perception , Visual Perception , Child, Preschool , Female , Follow-Up Studies , Humans , Infant, Newborn , Infant, Premature , Kinesthesis , Male , Matched-Pair Analysis , Neuropsychological Tests , Pregnancy , Pregnancy Trimester, Second , Pregnancy Trimester, Third , Prospective Studies , Touch
5.
Neuroreport ; 8(6): 1327-30, 1997 Apr 14.
Article in English | MEDLINE | ID: mdl-9172129

ABSTRACT

We compared event-related responses (ERPs) to non-attended frequent and intermittent auditory input in school-aged children and in young adults. In adults, both inputs elicited prominent auditory N100 responses at vertex. In children, intermittent stimulation evoked vertex responses with similar latency and refractoriness, whereas frequently delivered identical tones evoked responses on average at 240 ms. Sensitization of a separate neuronal population at 260-300 ms was obvious during intermittent stimulation in children. The dual behaviour, simultaneous 'habituation' of one neuronal population response and sensitization of another, may reflect the process of redirecting the attention and setting up a neuronal model. Furthermore, results suggest that a simplistic interpretation of developmental ERPs in which shortening of latencies represents maturation is insufficient.


Subject(s)
Aging/physiology , Evoked Potentials, Auditory/physiology , Mental Processes/physiology , Acoustic Stimulation , Adult , Child , Habituation, Psychophysiologic/physiology , Humans , Middle Aged , Neurons/physiology , Reaction Time/physiology
6.
Pharmacol Toxicol ; 75(6): 384-90, 1994 Dec.
Article in English | MEDLINE | ID: mdl-7899261

ABSTRACT

The effects of dichloromethylene bisphosphonate (clodronate) on the composition of bone mineral, morphology and histology of a long bone with an artificial femoral fracture were studied in a 22 week experiment. Two hundred twenty-four female rats were allocated to dose groups of 0, 3, 10, and 30 mg/kg clodronate daily subcutaneously. Bone calcium, phosphorus and magnesium concentrations remained stable and fluoride concentration rose with time. There were no statistical differences between different groups. Clodronate did not alter the histology of the callus nor delayed the healing of the fracture. It caused mild to moderate prominence of the metaphyseal area in the fractured bone in a dose- and time-dependent manner. Serum osteocalcin levels were lowered in the treated animals dose-dependently. Other serological as well as haematological values were within normal range. Clodronate seems in this experimental arrangement to be a safe agent to administer in different pathological conditions of bone even when they are complicated by fractures of long bones.


Subject(s)
Bone Density/drug effects , Clodronic Acid/pharmacology , Femoral Fractures/drug therapy , Fracture Healing/drug effects , Animals , Body Weight/drug effects , Calcium/metabolism , Clodronic Acid/administration & dosage , Clodronic Acid/therapeutic use , Disease Models, Animal , Dose-Response Relationship, Drug , Drinking/drug effects , Female , Femur/drug effects , Femur/pathology , Fluorides/metabolism , Humans , Injections, Subcutaneous , Magnesium/metabolism , Osteocalcin/blood , Osteoporosis, Postmenopausal/pathology , Phosphorus/metabolism , Rats , Rats, Sprague-Dawley
7.
Dev Med Child Neurol ; 35(12): 1083-96, 1993 Dec.
Article in English | MEDLINE | ID: mdl-7504639

ABSTRACT

Sixty children born preterm (gestational age < or = 32 weeks) and 60 control children matched by sex, and socio-economic and educational status of the parents were followed prospectively to the age of five years. Neurodevelopmental problems were surveyed by a detailed neurological and neuropsychological test battery, and by ophthalmological and hearing examinations. All except one of the preterm children with major disability had motor, visual-spatial and visual problems. The most frequent neurodevelopmental abnormalities encountered among preterm children without major disability were motor problems--emerging as gross and fine motor and/or visual-motor difficulties--and visual-spatial problems. Language difficulties were not associated with hearing problems. Among those without major disability, visual-spatial difficulties and ophthalmological problems seldom emerged simultaneously.


Subject(s)
Developmental Disabilities/diagnosis , Infant, Premature/growth & development , Nervous System/growth & development , Adult , Audiometry , Educational Status , Female , Follow-Up Studies , Humans , Infant, Newborn , Male , Neurologic Examination , Neuropsychological Tests , Parents , Prospective Studies , Socioeconomic Factors , Vision Tests
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