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Month-olds
Terms modified by Month-olds Selected AbstractsSimilar and functionally typical kinematic reaching parameters in 7- and 15-month-old in utero cocaine-exposed and unexposed infantsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2004E. Z. Tronick Abstract This study examined the effects of intrauterine cocaine exposure on the reaches of 19 exposed and 15 unexposed infants at 7 and 15 months using kinematic measures. Infants sat at a table and reached for a rattle, a toy doll, and a chair. Videotaped reaches were digitized using the Peak Performance system. Kinematic movement variables were extracted (e.g., reach duration, peak velocity, movement units, path length) and ratios computed (e.g., path length divided by number of movement units). Regardless of exposure status, reaches of older infants were faster, more direct, had fewer movement units, and covered more distance with the first movement unit. Exposed infants covered more distance per movement unit than unexposed infants, but there were no other significant differences. Reaches of exposed and unexposed infants were essentially similar. Importantly, reach parameters for these high-risk infants were similar to reach parameters for infants at lower social and biological risk. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 168,175, 2004. [source] Amplitude and Velocity of Mitral Annulus Motion in RabbitsECHOCARDIOGRAPHY, Issue 4 2004Li-ming Gan M.D., Ph.D. Objective: During recent years, the amplitude and the maximal systolic velocity of the mitral annulus motion (MAM) have been established as indices of the left ventricular systolic function and the maximal diastolic velocity of the annulus motion has been suggested as an index of diastolic function. The main aims of the present study were to investigate the feasibility of these techniques in rabbits and to investigate age-related changes concerning these variables. Methods: Twenty-one New Zealand white rabbits were investigated by echocardiographic M-mode and pulsed tissue Doppler. One subgroup (I) included 11 still-growing, 3.0 ± 0.2 month-old, animals and another group (II) included 10 young grown up rabbits, 12.1 ± 1.5 months old. Results: The amplitude (4.8 ± 0.6 and 3.5 ± 0.3 mm, respectively) and maximal systolic (98 ± 14 and 66 ± 7 mm/s, respectively) and diastolic (111 ± 21 and 80 ± 12 mm/s, respectively) velocities of the MAM were significantly (P < 0.001) higher in group I than in group II, despite a bigger heart in the animals in the latter group. A coefficient of variation of <5% was found for both inter- and intraobserver variability for both amplitude and velocities. Conclusions: The amplitude and velocities of MAM are easily recorded in rabbits with excellent reproducibility and the changes with age seem to be very similar to those in humans. These noninvasive M-mode and tissue Doppler methods are therefore suitable for the investigation of left ventricular function in experimental studies in rabbits. (ECHOCARDIOGRAPHY, Volume 21, May 2004) [source] Growth hormone stimulates proliferation of old-aged regenerating liver through forkhead box m1bHEPATOLOGY, Issue 6 2003Katherine Krupczak-Hollis The Forkhead Box (Fox) proteins are an extensive family of transcription factors that shares homology in the winged helix DNA-binding domain and the members of which play essential roles in cellular proliferation, differentiation, and longevity. Reduced cellular proliferation during aging is associated with a progressive decline in both growth hormone (GH) secretion and Foxm1b expression. Liver regeneration studies with 12-month-old (old-aged) transgenic mice indicated that increased hepatocyte expression of Foxm1b alone is sufficient to restore hepatocyte proliferation to levels found in 2-month-old (young) regenerating liver. GH therapy in older people has been shown to cause an increase in cellular proliferation, but the transcription factors that mediated this stimulation in proliferation remain uncharacterized. In this study, we showed that human GH administration to old-aged Balb/c mice dramatically increased both expression of Foxm1b and regenerating hepatocyte proliferation. This increase in old-aged regenerating hepatocyte proliferation was associated with elevated protein expression of Cdc25A, Cdc25B, and cyclin B1, with reduced protein levels of cyclin-dependent kinase inhibitor p27Kip1 (p27). GH treatment also was found to stimulate hepatocyte proliferation and expression of Foxm1b protein without partial hepatectomy (PHx). Furthermore, GH treatment of young Foxm1b ,/, mice failed to restore regenerating hepatocyte DNA replication and mitosis caused by Foxm1b deficiency. These genetic studies provided strong evidence that the presence of Foxm1b is essential for GH to stimulate regenerating hepatocyte proliferation. In conclusion, our old-aged liver regeneration studies show that increased Foxm1b levels are essential for GH to stimulate hepatocyte proliferation, thus providing a mechanism for GH action in the elderly. [source] Nonalcoholic steatohepatitis and hepatocellular carcinoma in galectin-3 knockout miceHEPATOLOGY RESEARCH, Issue 12 2008Yuko Nakanishi Aim:, Nonalcoholic fatty liver disease (NAFLD) represents a growing health concern due to its rapidly increasing prevalence worldwide. Nonalcoholic steatohepatitis (NASH) is a progressing form of NAFLD, and recently many studies have reported that it could eventually develop into hepatocellular carcinoma (HCC). We previously reported that 6-month-old male galectin-3 knockout (gal3,/,) mice developed clinicopathological features similar to those of NAFLD in humans. Our aim was to investigate the changes in liver histology in gal3,/, mice by long-term observation. Methods:, We initially investigated three 15-month-old gal3,/, mice, of which two developed multiple liver nodules with dysplastic changes. Then, we histopathologically examined the liver specimens of the 15-, 20- and 25-month-old gal3,/, mice and attempted to evaluate the liver morphology by contrast enhanced computed tomography (CT) before sacrifice. Results:, At the age of 15 months or later, gal3,/, mice developed liver nodules with varying degrees of architectural and nuclear atypia based on mild to moderate delicate zone 3 fibrosis. In addition, we successfully confirmed the presence of some of the liver nodules by CT. We report herein that gal3,/, mice develop dysplastic liver nodules and HCC. Conclusions:, We believe that it would be interesting to use this murine model to investigate liver carcinogenesis based on a natural history of NAFLD. Furthermore, CT scanning might be a useful tool for longitudinal evaluation of morphological changes in vivo. [source] Changes in the Ability to Detect Ordinal Numerical Relationships Between 9 and 11 Months of AgeINFANCY, Issue 4 2008Sumarga H. Suanda When are the precursors of ordinal numerical knowledge first evident in infancy? Brannon (2002) argued that by 11 months of age, infants possess the ability to appreciate the greater than and less than relations between numerical values but that this ability experiences a sudden onset between 9 and 11 months of age. Here we present 5 experiments that explore the changes that take place between 9 and 11 months of age in infants' ability to detect reversals in the ordinal direction of a sequence of arrays. In Experiment 1, we replicate the finding that 11- but not 9-month-old infants detect a numerical ordinal reversal. In Experiment 2 we rule out an alternative hypothesis that 11-month-old infants attended to changes in the absolute numerosity of the first stimulus in the sequence rather than a reversal in ordinal direction. In Experiment 3, we demonstrate that 9-month-old infants are not aided by additional exposure to each numerosity stimulus in a sequence. In Experiment 4 we find that 11-month-old but not 9-month-old infants succeed at detecting the reversal in a nonnumerical size or area-based rule, casting doubt on Brannon's prior claim that what develops between 9 and 11 months of age is a specifically numerical ability. In Experiment 5 we demonstrate that 9-month-old infants are capable of detecting a reversal in ordinal direction but only when there are multiple converging cues to ordinality. Collectively these data indicate that at 11 months of age infants can represent ordinal relations that are based on number, size, or cumulative area, whereas at 9 months of age infants are unable to use any of these dimensions in isolation but instead require a confluence of cues. [source] A syngeneic glioma model to assess the impact of neural progenitor target cell age on tumor malignancyAGING CELL, Issue 4 2009Andrei M. Mikheev Summary Human glioma incidence, malignancy, and treatment resistance are directly proportional to patient age. Cell intrinsic factors are reported to contribute to human age-dependent glioma malignancy, but suitable animal models to examine the role of aging are lacking. Here, we developed an orthotopic syngeneic glioma model to test the hypothesis that the age of neural progenitor cells (NPCs), presumed cells of glioma origin, influences glioma malignancy. Gliomas generated from transformed donor 3-, 12-, and 18-month-old NPCs in same-aged adult hosts formed highly invasive glial tumors that phenocopied the human disease. Survival analysis indicated increased malignancy of gliomas generated from older 12- and 18-month-old transformed NPCs compared with their 3-month counterparts (median survival of 38.5 and 42.5 vs. 77 days, respectively). This study showed for the first time that age of target cells at the time of transformation can affect malignancy and demonstrated the feasibility of a syngeneic model using transformed NPCs for future examination of the relative impacts of age-related cell intrinsic and cell-extrinsic factors in glioma malignancy. [source] Relative contribution of V-H+ATPase and NA+/H+ exchanger to bicarbonate reabsorption in proximal convoluted tubules of old ratsAGING CELL, Issue 5 2006Mariana Fiori Summary With aging, the kidney develops a progressive deterioration of several structures and functions. Proximal tubular acidification is impaired in old rats with a decrease in the activity of brush border Na+/H+ exchange and a fall of H-ion flux measured with micropuncture experiments. In the present work we evaluate the contribution of 5-N-ethyl-n-isopropyl amiloride- (EIPA) and bafilomycin-sensitive bicarbonate flux () in proximal convoluted tubules of young and aged rats. We performed micropuncture experiments inhibiting the Na+/H+ exchanger with EIPA (10,4 M) and the V-H+ATPase with bafilomycin (10,6 M). We used antibodies against the NHE3 isoform of the Na+/H+ exchanger and the subunit E of the V-H+ATPase for detecting by Western blot the abundance of these proteins in brush border membrane vesicles from proximal convoluted tubules of young and old rats. The abundance of NHE3 and the V-H+ATPase was similar in 18-month-old and 3-month-old rats. The bicarbonate flux in old rats was 30% lower than in young rats. EIPA reduced by 60% and bafilomycin by 30% in young rats; in contrast, EIPA reduced by ,40% and bafilomycin by ,50% in old rats. The inhibited by bafilomycin was the same in young and old rats: 0.62 nmol · cm,2· s,1 and 0.71 nmol · cm,2· s,1, respectively. However, the EIPA-sensitive fraction was larger in young than in old rats: 1.26 nmol · cm,2· s,1 vs. 0.85 nmol · cm,2· s,1, respectively. These results suggest that the component more affected in bicarbonate reabsorption of proximal convoluted tubules from aged rats is the Na+ -H+ exchanger, probably a NHE isoform different from NHE3. [source] Reduced age-related plasticity of neurotrophin receptor expression in selected sympathetic neurons of the ratAGING CELL, Issue 1 2003T. Cowen Summary Selective vulnerability of particular groups of neurons is a characteristic of the aging nervous system. We have studied the role of neurotrophin (NT) signalling in this phenomenon using rat sympathetic (SCG) neurons projecting to cerebral blood vessels (CV) and iris which are, respectively, vulnerable to and protected from atrophic changes during old age. RT-PCR was used to examine NT expression in iris and CV in 3- and 24-month-old rats. NGF and NT3 expression in iris was substantially higher compared to CV; neither target showed any alterations with age. RT-PCR for the principal NT receptors, trkA and p75, in SCG showed increased message during early postnatal life. However, during mature adulthood and old age, trkA expression remained stable while p75 declined significantly over the same period. In situ hybridization was used to examine receptor expression in subpopulations of SCG neurons identified using retrograde tracing. Eighteen to 20 h following local treatment of iris and CV with NGF, NT3 or vehicle, expression of NT receptor protein and mRNA was higher in iris- compared with CV-projecting neurons from both young and old rats. NGF and NT3 treatment had no effect on NT receptor expression in CV-projecting neurons at either age. However, similar treatment up-regulated p75 and trkA expression in iris-projecting neurons from 3-month-old, but not 24-month-old, rats. We conclude that lifelong exposure to low levels of NTs combined with impaired plasticity of NT receptor expression are predictors of neuronal vulnerability to age-related atrophy. [source] DNA damage, p53 gene expression and p53 protein level in the rat brain agingJOURNAL OF NEUROCHEMISTRY, Issue 2003J. Dorszewska The aging induces free radicals leading to DNA damage (8-oxo-2,-deoxyguanosine, 8-oxo2dG). DNA injury causes increased expression of p53 gene and p53 protein. Levels of 8-oxo2dG (HPLC), p53 mRNA (PCR) and p53 protein (Western blot) were estimated in gray matter (GM), white matter (WM), cerebellum (C) and medulla oblongata (MO) of control, 12- and 24-month-old rats. The level of 8-oxo2dG increased with age in C (P < 0.05 in 12-month-old and P < 0.01 in 24-month-old rats) and MO. In 12-month-old animals the level of 8-oxo2dG in GM and WM was higher than in controls. In 12-month-old animals p53 gene expression decreased while amounts of p53 protein increased, depending on the oxidative DNA damage. In 24-month-old rats, expression of p53 increased in all structures (P , 0.05) while p53 protein showed decreased levels in most of structures of central nervous system (WM, C, MO). Aging leads to increased 8-oxo2dG and augmented p53 gene expression, accompanied by a lowered expression of p53 protein. [source] Innovative Techniques for Placement of Implantable Cardioverter-Defibrillator Leads in Patients with Limited Venous Access to the HeartPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2006BRYAN C. CANNON Background: Because of venous occlusion, intracardiac shunting, previous surgery, or small size placement of implantable cardioverter-defibrillator (ICD) leads may not be possible using traditional methods. The purpose of this study was to evaluate and describe innovative methods of placing ICD leads. Methods: The records of all patients undergoing ICD implantation at our institution were reviewed to identify patients with nontraditional lead placement. Indications for ICD, method of lead and coil placement, defibrillation thresholds, complications, and follow-up results were reviewed retrospectively. Results: Eight patients (aged 11 months to 29 years) were identified. Six patients with limited venous access to the heart (four extracardiac Fontan, one bidirectional Glenn, one 8 kg 11-month-old) underwent surgical placement of an ICD coil directly into the pericardial sac. A second bipolar lead was placed on the ventricle for sensing and pacing. Two patients with difficult venous access had a standard transvenous ICD lead inserted directly into the right atrium (transatrial approach) and then positioned into the ventricle. All patients had a defibrillation threshold of <20 J, although one patient required placement of a second coil due to an elevated threshold. There have been no complications and two successful appropriate ICD discharges at follow-up (median 22 months, range 5,42 months). Conclusions: Many factors may prohibit transvenous ICD lead placement. Nontraditional surgical placement of subcutaneous ICD leads on the pericardium or the use of a transatrial approach can be effective techniques in these patients. These procedures can be performed at low risk to the patient with excellent defibrillation thresholds. [source] Differential diagnosis of food-induced symptomsPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 1 2008Birgit Ahrens The symptoms of patients presenting with non-allergic food-related reactions may partly mimic allergic responses. Therefore, correct delineation of food allergies is often difficult and various differential diagnoses have to be considered. We describe three cases of differential diagnoses to food-induced symptoms: A 14-month-old with lactose intolerance, an 8-month-old with severe diet-induced malnutrition and subsequent development of kwashiorkor and a 12-yr-old with chronic urticaria due to colouring agents. These cases represent common symptom constellations involving food-induced reactions. A proper and correct diagnosis of food-related symptoms is particularly important for children , not only in order to find the appropriate diet but also to avoid unnecessary exclusion diets, which may lead to severe impairments in growth and development. [source] The Use of Bivalirudin for Cardiopulmonary Bypass Anticoagulation in Pediatric Heparin-Induced Thrombocytopenia PatientsARTIFICIAL ORGANS, Issue 8 2010Richard Gates Abstract Infants with heparin-induced thrombocytopenia (HIT) represent a challenging and high-risk group of patients when they require cardiopulmonary bypass (CPB). Bivalirudin offers many potential pharmacologic advantages over other nonheparin anticoagulants for such patients. We describe our protocol for the use of bivalirudin in a 5-month-old infant undergoing stage 2 Norwood for hypoplastic left heart syndrome. The patient was a 5- month-old, 6-kg infant who developed HIT after a bowel resection complicating initial Norwood stage 1. After sternotomy and dissection had been redone, the child received an initial dose of bivalirudin of 1.0 mg/kg and 0.5 mg/kg 5 min later. The CPB circuit was primed with 50 mg/kg bivalirudn/400 cc volume. With the initiation of CPB, a continuous infusion of 2.5 mg/kg bivalirudin was begun. Activated clotting time (ACT) was targeted for over 400 s, with an examination prior to bypass and each 15 min thereafter. Bivalirudin was discontinued with separation from bypass and during modified ultrafiltration (MUF). The ACT was 286 s after the initial 1 mg/kg bolus and 597 s after the second 0.5 mg/kg bolus and initiation of CPB. At a rate of 2.5 mg/kg/min, ACT ranged between 461 and 597 s. At the completion of MUF, the ACT was 316 s. The ACT was 214 s 20 min after MUF. No clots were noted in the CPB circuit, and good hemostasis was achieved within 10 min after MUF was completed. Incision to closure time was 160 min; time from completion of MUF to sternal closure was 30 min. Post-MUF, 60 cc of processed cell saver blood was reinfused, and no clotting factors were required. Chest tube output was 10, 10, 3, and 4 ccs, respectively, at hours 1,4 post operation. Bivalirudin provides effective anticoagulation in infants requiring CPB in the presence of HIT. Bivalirudin's efficacy is effectively monitored by ACT, and, after CPB, its short half-life and ability to be ultrafiltered facilitate the ability to achieve hemostasis in a timely fashion. [source] Metoprolol Treatment Lowers Thrombospondin-4 Expression in Rats with Myocardial Infarction and Left Ventricular HypertrophyBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2010Erja Mustonen In this study, we characterised left ventricular thrombospondin-1 and -4 expression in rats treated with a beta-blocker metoprolol during the remodelling process in response to pressure overload and acute myocardial infarction. Left ventricular thrombospondin-1 and thrombospondin-4 mRNA levels increased 8.4-fold (p < 0.001) and 7.3-fold (p < 0.001) post-infarction, respectively. Metoprolol infusion by osmotic minipumps (1.5 mg/kg/hr) for 2 weeks after myocardial infarction decreased thrombospondin-1 and thrombospondin-4 mRNA levels (55% and 50%, respectively), improved left ventricular function, and attenuated left ventricular remodelling with reduction of left ventricular atrial natriuretic peptide and brain natriuretic peptide gene expression. Thrombospondin-1 and -4 mRNA levels correlated positively with echocardiographic parameters of left ventricular remodelling as well as with atrial natriuretic peptide and brain natriuretic peptide gene expression. Moreover, there was a negative correlation between left ventricular ejection fraction and thrombospondin-1 mRNA levels. In 12-month-old spontaneously hypertensive rats with left ventricular hypertrophy, metoprolol decreased left ventricular thrombospondin-4 levels and attenuated remodelling while thrombospondin-1, atrial natriuretic peptide and brain natriuretic peptide mRNA levels as well as left ventricular function remained unchanged. In metoprolol-treated spontaneously hypertensive rats, thrombospondin-4 gene expression correlated with parameters of left ventricular remodelling, while no correlations between thrombospondins and natriuretic peptides were observed. These results indicate that thrombospondin-1 expression is linked exclusively to left ventricular remodelling process post-infarction while thrombospondin-4 associates with myocardial remodelling both after myocardial infarction and in hypertensive heart disease suggesting that thrombospondins may have unique roles in extracellular matrix remodelling process. [source] Incidence, management and mortality of acute hypoxemic respiratory failure and acute respiratory distress syndrome from a prospective study of Chinese paediatric intensive care networkACTA PAEDIATRICA, Issue 5 2010X Hu Abstract Aim:, To investigate the incidence, clinical management, mortality and its risk factors, major outcome and costs of acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS) in a Chinese network of 26 paediatric intensive care unit (PICU). Methods: In a consecutive 12-month period, AHRF and ARDS were identified and followed up for 90 days or until death or discharge. Results:, From a total of 11 521 critically ill patients, 461 AHRF were identified in which 306 developed ARDS (66.4%), resulting in incidences of 4% and 2.7%, respectively, with pneumonia (75.1%) and sepsis (14.7%) as main underlying diseases and 83% were 5 years and 1 month-old. In-hospital mortality of AHRF was 41.6% (44.8% for ARDS), accounted for 15.5% of all PICU deaths. For those of pneumonia or sepsis with AHRF and ARDS, mortality and its relative risk were significantly higher than those without. Relatively lower tidal volume and total fluid balance, adequate upper limit of PaCO2 in the early PICU days, and family affordability, tended to result in better outcome. Conclusion:, In this prospective study, AHRF had high possibilities to develop ARDS and death risk, as impacted by ventilation settings and fluid intake in the early treatment, as well as socioeconomic factors, which should be considered for implementation of standard of care in respiratory therapy. [source] Neurocognitive Function and Joint Attention Ability in Young Children with Autism Spectrum Disorder Versus Developmental DelayCHILD DEVELOPMENT, Issue 2 2002Geraldine Dawson Studies have shown that young children with autism are not impaired on prefrontal tasks relative to what would be expected for their mental age, raising questions about the executive dysfunction hypothesis of autism. These studies did not include ventromedial prefrontal tasks, however. The present study examined whether young children with autism spectrum disorder (ASD) are impaired on ventromedial prefrontal tasks, and whether performance on such tasks is correlated with a core autism symptom, joint attention ability. Seventy-two 3- to 4-year-old children with ASD, 34 3- to 4-year-old developmentally delayed children, and 39 12- to 46-month-old typically developing children, matched on mental age, were administered ventromedial and dorsolateral prefrontal tasks and joint attention tasks. Children with ASD performed similarly to comparison groups on all executive function tasks, indicating that at this early age, there is no autism-specific pattern of executive dysfunction. Ventromedial, but not dorsolateral, prefrontal task performance was strongly correlated with joint attention ability, however. The ventromedial prefrontal cortex is hypothesized to play a role in the development of joint attention and possibly some aspects of the autistic syndrome. [source] Something old, something new: a developmental transition from familiarity to novelty preferences with hidden objectsDEVELOPMENTAL SCIENCE, Issue 2 2010Jeanne L. Shinskey Novelty seeking is viewed as adaptive, and novelty preferences in infancy predict cognitive performance into adulthood. Yet 7-month-olds prefer familiar stimuli to novel ones when searching for hidden objects, in contrast to their strong novelty preferences with visible objects (Shinskey & Munakata, 2005). According to a graded representations perspective on object knowledge, infants gradually develop stronger object representations through experience, such that representations of familiar objects can be better maintained, supporting greater search than with novel objects. Object representations should strengthen with further development to allow older infants to shift from familiarity to novelty preferences with hidden objects. The current study tested this prediction by presenting 24 11-month-olds with novel and familiar objects that were sometimes visible and sometimes hidden. Unlike 7-month-olds, 11-month-olds showed novelty preferences with both visible and hidden objects. This developmental shift from familiarity to novelty preference with hidden objects parallels one that infants show months earlier with perceptible stimuli, but the two transitions may reflect different underlying mechanisms. The current findings suggest both change and continuity in the adaptive development of object representations and associated cognitive processes. [source] The development of gaze following and its relation to languageDEVELOPMENTAL SCIENCE, Issue 6 2005Rechele Brooks We examined the ontogeny of gaze following by testing infants at 9, 10 and 11 months of age. Infants (N = 96) watched as an adult turned her head toward a target with either open or closed eyes. The 10- and 11-month-olds followed adult turns significantly more often in the open-eyes than the closed-eyes condition, but the 9-month-olds did not respond differentially. Although 9-month-olds may view others as ,body orienters', older infants begin to register whether others are ,visually connected' to the external world and, hence, understand adult looking in a new way. Results also showed a strong positive correlation between gaze-following behavior at 10,11 months and subsequent language scores at 18 months. Implications for social cognition are discussed in light of the developmental shift in gaze following between 9 and 11 months of age. [source] The origins and evolution of links between word learning and conceptual organization: new evidence from 11-month-oldsDEVELOPMENTAL SCIENCE, Issue 2 2003Sandra Waxman How do infants map words to their meaning? How do they discover that different types of words (e.g. noun, adjective) refer to different aspects of the same objects (e.g. category, property)? We have proposed that (1) infants begin with a broad expectation that novel open-class words (both nouns and adjectives) highlight commonalities (both category- and property-based) among objects, and that (2) this initial expectation is subsequently fine-tuned through linguistic experience. We examine the first part of this proposal, asking whether 11-month-old infants can construe the very same set of objects (e.g. four purple animals) either as members of an object category (e.g. animals) or as embodying a salient object property (e.g. four purple things), and whether naming (with count nouns vs. adjectives) differentially influences their construals. Results support the proposal. Infants treated novel nouns and adjectives identically, mapping both types of words to both category- and property-based commonalities among objects. [source] Finding the Signal by Adding Noise: The Role of Noncontrastive Phonetic Variability in Early Word LearningINFANCY, Issue 6 2010Gwyneth C. Rost It is well attested that 14-month-olds have difficulty learning similar sounding words (e.g., bih/dih), despite their excellent phonetic discrimination abilities. By contrast, Rost and McMurray (2009) recently demonstrated that 14-month-olds' minimal-pair learning can be improved by the presentation of words by multiple talkers. This study investigates which components of the variability found in multitalker input improved infants' processing, assessing both the phonologically contrastive aspects of the speech stream and phonologically irrelevant indexical and suprasegmental aspects. In the first two experiments, speaker was held constant while cues to word-initial voicing were systematically manipulated. Infants failed in both cases. The third experiment introduced variability in speaker, but voicing cues were invariant within each category. Infants in this condition learned the words. We conclude that aspects of the speech signal that have been typically thought of as noise are in fact valuable information,signal,for the young word learner. [source] Language Experience Shapes the Development of the Mutual Exclusivity BiasINFANCY, Issue 2 2010Carmel Houston-Price Halberda (2003) demonstrated that 17-month-old infants, but not 14- or 16-month-olds, use a strategy known as mutual exclusivity (ME) to identify the meanings of new words. When 17-month-olds were presented with a novel word in an intermodal preferential looking task, they preferentially fixated a novel object over an object for which they already had a name. We explored whether the development of this word-learning strategy is driven by children's experience of hearing only one name for each referent in their environment by comparing the behavior of infants from monolingual and bilingual homes. Monolingual infants aged 17,22 months showed clear evidence of using an ME strategy, in that they preferentially fixated the novel object when they were asked to "look at the dax." Bilingual infants of the same age and vocabulary size failed to show a similar pattern of behavior. We suggest that children who are raised with more than one language fail to develop an ME strategy in parallel with monolingual infants because development of the bias is a consequence of the monolingual child's everyday experiences with words. [source] Better Processing of Consonantal Over Vocalic Information in Word Learning at 16 Months of AgeINFANCY, Issue 4 2009Mélanie Havy Previous research using the name-based categorization task has shown that 20-month-old infants can simultaneously learn 2 words that only differ by 1 consonantal feature but fail to do so when the words only differ by 1 vocalic feature. This asymmetry was taken as evidence for the proposal that consonants are more important than vowels at the lexical level. This study explores this consonant-vowel asymmetry in 16-month-old infants, using an interactive word learning task. It shows that the pattern of the 16-month-olds is the same as that of the 20-month-olds. Infants succeeded with 1-feature consonantal contrasts (either place or voicing) but were at chance level with 1-feature vocalic contrasts (either place or height). These results thus contribute to a growing body of evidence establishing, from early infancy to adulthood, that consonants and vowels have different roles in lexical acquisition and processing. [source] The Role of Verbal Repetition in the Development of Infant Speech Preferences From 4 to 14 Months of AgeINFANCY, Issue 2 2009Gerald W. McRoberts Four experiments investigated infants' preferences for age-appropriate and age-inappropriate infant-directed speech (IDS) over adult-directed speech (ADS). Two initial experiments showed that 6-, 10-, and 14-month-olds preferred IDS directed toward younger infants, and 4-, 8-, 10-, and 14-month-olds, but not 6-month-olds, preferred IDS directed toward older infants. In Experiment 3. 6-month-olds preferred IDS directed toward older infants when the frequency of repeated utterances matched IDS to younger infants. In Experiment 4, 6-month-olds preferred repeated IDS utterances over the same IDS utterances organized without repetition. Attention to repeated utterances precedes word segmentation and sensitivity to statistical cues in continuous speech, and might play a role in the discovery of these and other aspects of linguistic structure. [source] The Development of Affect Specificity in Infants' Use of Emotion CuesINFANCY, Issue 5 2008Nicole Gendler Martin This study examined the emergence of affect specificity in infancy. In this study, infants received verbal and facial signals of 2 different, negatively valenced emotions (fear and sadness) as well as neutral affect via a television monitor to determine if they could make qualitative distinctions among emotions of the same valence. Twenty 12- to 14-month-olds and 20 16- to 18-month-olds were examined. Results suggested that younger infants showed no evidence of referential specificity, as they responded similarly to both the target and distracter toys, and showed no evidence of affect specificity, showing no difference in play between affect conditions. Older infants, in contrast, showed evidence both of referential and affect specificity. With respect to affect specificity, 16- to 18-month-olds touched the target toy less in the fear condition than in the sad condition and showed a larger proportion of negative facial expressions in the sad condition versus the fear condition. These findings suggest a developmental emergence after 15 months of age for affect specificity in relating emotional messages to objects. [source] The Effect of Vocabulary Size on Toddlers' Receptiveness to Unexpected Testimony About Category MembershipINFANCY, Issue 2 2007Vikram K. Jaswal Children must be willing to accept some of what they hear "on faith," even when that testimony conflicts with their own expectations. The study reported here investigated the relation among vocabulary size, object recognition, and 24-month-olds' (N = 40) willingness to accept potentially surprising testimony about the category to which an object belongs. Results showed that children with larger vocabularies were better able to recognize atypical exemplars of familiar categories than children with smaller vocabularies. However, they were also most likely to accept unexpected testimony that an object that looked like a member of one familiar category was actually a member of another. These results indicate that 24-month-olds trust classifications provided by adult labeling patterns even when they conflict with the classifications children generate on their own. [source] Encoding Action Roles in Meaningful Social Interaction in the First Year of LifeINFANCY, Issue 3 2006Barbara Schöppner Previous research has shown that 6- to 9-month-old infants detect role reversals in dyadic interaction involving 2-argument relations. These studies extend this line of research to a 3-argument structure: An agent gives an object to a recipient. We conducted 4 experiments in a novelty-preference paradigm. Infants were habituated to videotaped sequences of a puppet giving a flower to another puppet. In the test phase, the puppets' spatial positions were switched, and infants alternately saw role-reversal and direction-reversal trials. Results indicate that 10.5- and 12-month-olds but not 9-month-olds selectively encoded the change of action role (agent-recipient) over a change in the spatiotemporal properties of the interaction and that action role encoding was specific to intentional relations in a 3-argument structure. Thus, infants at the end of their 1st year seem to be sensitive to movement cues that specify intentional relations between an agent and a recipient. [source] Modeling Age Differences in Infant Category LearningINFANCY, Issue 2 2004Thomas R. Shultz We used an encoder version of cascade correlation to simulate Younger and Cohen's (1983, 1986) finding that 10-month-olds recover attention on the basis of correlations among stimulus features, but 4- and 7-month-olds recover attention on the basis of stimulus features. We captured these effects by varying the score threshold parameter in cascade correlation, which controls how deeply training patterns are learned. When networks learned deeply, they showed more error to uncorrelated than to correlated test patterns, indicating that they abstracted correlations during familiarization. When prevented from learning deeply, networks decreased error during familiarization and showed as much error to correlated as to uncorrelated tests but less than to test items with novel features, indicating that they learned features but not correlations among features. Our explanation is that older infants learn more from the same exposure than do younger infants. Unlike previous explanations that postulate unspecified qualitative shifts in processing with age, our explanation focuses on quantitatively deeper learning with increasing age. Finally, we provide some new empirical evidence to support this explanation. [source] The Influence of Labels, Non-Labeling Sounds, and Source of Auditory Input on 9- and 15-Month-Olds' Object CategorizationINFANCY, Issue 3 2003Anne L. Fulkerson This experiment examines the joint influence of auditory and social cues on infants' basic-level and global categorization. Nine- and fifteen-month-olds were familiarized to a series of category exemplars in an object-examining task. Objects were introduced with a labeling phrase, a non-labeling sound, or no sound, and auditory input was presented orally by the experimenter or played on a hidden voice recorder. Novel objects from the familiarized category and a contrasting category were then presented. Results of analyses performed on novelty preference scores indicated that infants demonstrated basic-level categorization in all conditions. However, infants at both age levels only demonstrated global categorization when labeling phrases were introduced. In addition, labels led to global categorization in 9-month-olds regardless of the source of those labels; however, labels only led to global categorization in 15-month-olds when the labels were presented orally by the experimenter. [source] Speed of Processing and Face Recognition at 7 and 12 MonthsINFANCY, Issue 4 2002Susan A. Rose This research examined developmental and individual differences in infants' speed of processing faces and the relation of processing speed to the type of information encoded. To gauge processing speed, 7- and 12-month-olds were repeatedly presented with the same face (frontal view), each time paired with a new one, until they showed a consistent preference for the new one. Subsequent probe trials assessed recognition of targets that either preserved configural integrity (Study 1: 3/4 profile and full profile poses) or disrupted it while preserving featural information (Study 2: rotations of 160° or 200° and fracturings). There were developmental differences in both speed and in infants' appreciation of information about faces. Older infants took about 60% fewer trials to reach criterion and had more mature patterns of attention (i.e., looks of shorter duration and more shifts of gaze). Whereas infants of both ages recognized the familiar face in a 3/4 pose, the 12-month-olds also recognized it in profile and when rotated. Twelve-month-olds who were fast processors additionally recognized the fractured faces; otherwise, processing speed was unrelated to the type of information extracted. At 7 months then, infants made use of some configural information in processing faces; at 12 months, they made use of even more of the configural information, along with part-based or featural information. [source] Children's performance on the ,give x' task: a microgenetic analysis of ,counting' and ,grabbing' behaviourINFANT AND CHILD DEVELOPMENT, Issue 1 2007Elizabeth Chetland Abstract Children's understanding of the cardinal significance of counting is often assessed by the ,give x' task, in which they are categorized as ,counters' or ,grabbers'. Previous research indicates a sudden stage-like shift, implying insight into a principle. Employing a microgenetic approach, the present study was designed to explore whether this dichotomy masks a more subtle pattern. Fifty-five 39- to 58-month-olds received five ,give x' trials, involving 4, 5, 6, 7, and 10 objects, within a single session counterbalanced across individuals, each child participating in two similar sessions one week apart. Children's spontaneous strategies were recorded. They also completed a simple verbal counting test. Participants seldom simply ,grabbed'; even those who never counted gave items one-by-one. Some gave correct amounts by starting off counting then taking the remainder silently, suggesting internal counting. There was also evidence of children taking correct non -subitizable quantities without overtly counting. Individuals' strategy choice and the way they employed particular strategies varied, both within and between sessions. Furthermore, after achieving procedural mastery, children continued to refine their use of strategies. The results are discussed in relation to Karmiloff-Smith's RR model and Siegler's overlapping waves model. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mother versus stranger: a triadic situation of imitation at the end of the first year of lifeINFANT AND CHILD DEVELOPMENT, Issue 1 2004Emmanuel DevoucheArticle first published online: 26 NOV 200 Abstract This study presents two experiments investigating 8- and 12-month-old infants' imitative behaviour. Seventy-two 8-month-olds and seventy-two 12-month-olds were observed in a triadic situation which included their mother and a stranger. Depending on the condition, either the mother or the stranger acted as the demonstrator and either stayed close or withdrew after the demonstration, during the response period. In addition to imitative acts, visual exploration and smiles addressed, respectively, to each partner were computed. Results showed that at both ages, neither the familiarity nor the position of the partner has an effect on the number of target gestures that are imitated. At 12 months, infants looked and smiled more at the stranger when he demonstrated target actions but no difference was found when the mother acted as demonstrator. Moreover, 12-month-old infants looked more at the demonstrating partner immediately after their first imitation. At 8 months, infants paid more attention to the stranger in all conditions except when the mother performed the target actions and moved away, a pattern that suggests a referencing to the mother. Results from the gaze and smile variables suggest that with age different motivations (social contact, exploration of objects) induce imitation. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||