			Home About us Contact

Maturational Changes (maturational + change)

Distribution by Scientific Domains

Medical Sciences	57%

Selected Abstracts

Age-related changes in transient and oscillatory brain responses to auditory stimulation during early adolescence

DEVELOPMENTAL SCIENCE, Issue 2 2009
Catherine Poulsen
Maturational changes in the capacity to process quickly the temporal envelope of sound have been linked to language abilities in typically developing individuals. As part of a longitudinal study of brain maturation and cognitive development during adolescence, we employed dense-array EEG and spatiotemporal source analysis to characterize maturational changes in the timing of brain responses to temporal variations in sound. We found significant changes in the brain responses compared longitudinally at two time points in early adolescence, namely 10 years (65 subjects) and 11.5 years (60 of the 65 subjects), as well as large differences between adults, studied with the same protocol (Poulsen, Picton & Paus, 2007), and the children at 10 and 11.5 years of age. The transient auditory evoked potential to tone onset showed decreases in the latency of vertex and T-complex components, and a highly significant increase in the amplitude of the N1 wave with increasing age. The auditory steady state response to a 40-Hz frequency-modulated tone increased in amplitude with increasing age. The peak frequency of the envelope-following response to sweeps of amplitude-modulated white noise also increased significantly with increasing age. These results indicate persistent maturation of the cortical mechanisms for auditory processing from childhood into middle adulthood. [source]

Maturational changes in the feeding behaviour of infants , a comparison between breast-feeding and bottle-feeding

ACTA PAEDIATRICA, Issue 1 2010
M Taki
Abstract Aim:, To obtain a better understanding of the changes in feeding behaviour from 1 to 6 months of age. By comparing breast- and bottle-feeding, we intended to clarify the difference in longitudinal sucking performance. Methods:, Sucking variables were consecutively measured for 16 breast-fed and eight bottle-fed infants at 1, 3 and 6 months of age. Results:, For breast-feeding, number of sucks per burst (17.8 ± 8.8, 23.8 ± 8.3 and 32.4 ± 15.3 times), sucking burst duration (11.2 ± 6.1, 14.7 ± 8.0 and 17.9 ± 8.8 sec) and number of sucking bursts per feed (33.9 ± 13.9, 28.0 ± 18.2 and 18.6 ± 12.8 times) at 1, 3 and 6 months of age respectively showed significant differences between 1 and 6 months of age (p < 0.05). The sucking pressure and total number of sucks per feed did not differ among different ages. Bottle-feeding resulted in longer sucking bursts and more sucks per burst compared with breast-feeding in each month (p < 0.05). Conclusion:, The increase in the amount of ingested milk with maturation resulted from an increase in bolus volume per minute as well as the higher number of sucks continuously for both breast- and bottle-fed infants. [source]

Age-related changes in transient and oscillatory brain responses to auditory stimulation during early adolescence

Descending respiratory polysynaptic inputs to cervical and thoracic motoneurons diminish during early postnatal maturation in rat spinal cord

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005
Laurent Juvin
Abstract Isolated brainstem-spinal cord preparations were used to explore the coexistence of a direct and an indirect descending drive from the brainstem respiratory centre to cervical and thoracic respiratory motoneurons in the neonatal Sprague,Dawley rat. Polysynaptic spinal relay pathways from the respiratory centre were suppressed by selectively perfusing the cord with mephenesin (1 mm) or a solution enriched with Ca2+ and Mg2+. At birth, both direct and spinally relayed pathways are functional and contribute equally to the global descending respiratory drive. However, during the first postnatal week, significant maturational changes appear in the way the respiratory centre controls its target respiratory motoneurons in the cervical and thoracic spinal cord, with the direct respiratory drive becoming progressively predominant with maturation (from 50% to around 75% of the global descending command). The relative contributions of the monosynaptic and the polysynaptic spinal pathways may therefore have important implications for effective respiratory control during early postnatal development. [source]

Recent Discoveries on the Control of Gonadotrophin-Releasing Hormone Neurones in Nonhuman Primates

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2010
E. Terasawa
Since Ernst Knobil proposed the concept of the gonadotrophin-releasing hormone (GnRH) pulse-generator in the monkey hypothalamus three decades ago, we have made significant progress in this research area with cellular and molecular approaches. First, an increase in pulsatile GnRH release triggers the onset of puberty. However, the question of what triggers the pubertal increase in GnRH is still unclear. GnRH neurones are already mature before puberty but GnRH release is suppressed by a tonic GABA inhibition. Our recent work indicates that blocking endogenous GABA inhibition with the GABAA receptor blocker, bicuculline, dramatically increases kisspeptin release, which plays an important role in the pubertal increase in GnRH release. Thus, an interplay between the GABA, kisspeptin, and GnRH neuronal systems appears to trigger puberty. Second, cultured GnRH neurones derived from the olfactory placode of monkey embryos exhibit synchronised intracellular calcium, [Ca2+]i, oscillations and release GnRH in pulses at approximately 60-min intervals after 14 days in vitro (div). During the first 14 div, GnRH neurones undergo maturational changes from no [Ca2+]i oscillations and little GnRH release to the fully functional state. Recent work also shows GnRH mRNA expression increases during in vitro maturation. This mRNA increase coincides with significant demethylation of a CpG island in the GnRH 5,-promoter region. This suggests that epigenetic differentiation occurs during GnRH neuronal maturation. Third, oestradiol causes rapid, direct, excitatory action in GnRH neurones and this action of oestradiol appears to be mediated through a membrane receptor, such as G-protein coupled receptor 30. [source]

The study of chromatic and achromatic VEP in the first year of life

ACTA OPHTHALMOLOGICA, Issue 2009
M TEKAVCIC POMPE
Purpose To study chromatic and achromatic VEP responses in the first year of life. Methods In 30 babies aged 2 to 12 months VEP to chromatic and achromatic stimuli were binocularly recorded. Chromatic VEP were recorded to isoluminant red-green and blue-yellow stimulus. The stimulus was a circle composed of horizontal sinusoidal gratings with 90 % chromatic contrast. Two stimulus sizes (7 deg and 21 deg) were used. The stimulus was presented in an onset-offset mode (on , 300ms, off , 700 ms). Achromatic VEP were recorded to black and white checkerboard (50, square size), which was presented in pattern reversal (reversal VEP) and onset-offset (onset VEP) mode. VEP were recorded from Oz (mid occipital) position and the reference was at Fz. Results Chromatic VEP responses were present in all babies, except youngest two (2 months old). The positive wave (P) amplitude to red-green and blue-yellow stimulus increased with age when using both stimulus sizes. Achromatic VEP responses were present in all babies. P100 wave (pattern reversal stimulation) showed longer latency in youngest babies (p=0.045), whereas its amplitude did not change throughout the first year of life. C1 wave (onset-offset stimulation) showed longer latency in youngest babies (p=0.0039), whereas its amplitude decreased with increasing age (p=0.0087). Conclusion Chromatic VEP responses can be recorded in babies after the age of 3 months and show marked maturational changes throughout the first year of life. [source]

Developmental monitoring using caregiver reports in a resource-limited setting: the case of Kilifi, Kenya

ACTA PAEDIATRICA, Issue 2 2010
A Abubakar
Abstract Aim:, The main aim of the current study was to evaluate the reliability, validity and acceptability of developmental monitoring using caregiver reports among mothers in a rural African setting. Methods:, A structured interview for parents of children aged 24 months and less was developed through both participant consultation and a review of literature. The reliability and validity of the schedule was evaluated through a 10-month monitoring programme of 95 children, aged 2,10 months. The acceptability of the process was evaluated by studying retention rates and by organizing focus group discussions with participating mothers. Results:, The structured interview ,Developmental Milestones Checklist' consisted of 66 items covering three broad domains of child functioning: motor, language and personal,social development. The interview yielded scores of developmental achievements that showed high internal consistency and excellent test,retest reliability. The results were sensitive to maturational changes and nutritional deficiencies. In addition, acceptable retention rates of approximately 80% were found. Participating mothers reported that they found the procedures both acceptable and beneficial. Conclusion:, Developmental monitoring using caregiver report is a viable method to identify and monitor at-risk children in Sub-Saharan Africa. [source]