This dissertation explores the nature and ontogeny of infants' ability to match phonetic information in comparison to non-speech information in the face and voice. Previous research shows that infants' ability to match phonetic information in face and voice is robust at 4.5 months of age (e.g., Kuhl & Meltzoff, 1982; 1984; 1988; Patterson & Werker, 1999). These findings support claims that young infants can perceive structural correspondences between audio and visual aspects of phonetic input and that speech is represented amodally. It remains unclear, however, specifically what factors allow speech to be perceived amodally and whether the intermodal perception of other aspects of face and voice is like that of speech. Gender is another biologically significant cue that is available in both the face and voice. In this dissertation, nine experiments examine infants' ability to match phonetic and gender information with dynamic faces and voices. Infants were seated in front of two side-by-side video monitors which displayed filmed images of a female or male face, each articulating a vowel sound ( / a / or / i / ) in synchrony. The sound was played through a central speaker and corresponded with one of the displays but was synchronous with both. In Experiment 1,4.5-month-old infants did not look preferentially at the face that matched the gender of the heard voice when presented with the same stimuli that produced a robust phonetic matching effect. In Experiments 2 through 4, vowel and gender information were placed in conflict to determine the relative contribution of each in infants' ability to match bimodal information in the face and voice. The age at which infants do match gender information with my stimuli was determined in Experiments 5 and 6. In order to explore whether matching phonetic information in face and voice is based on featural or configural information, two experiments examined infants' ability to match phonetic information using inverted faces (Experiment 7) and upright faces with inverted mouths (Experiment 8). Finally, Experiment 9 extended the phonetic matching effect to 2-month-old infants. The experiments in this dissertation provide evidence that, at 4.5 months of age, infants are more likely to attend to phonetic information in the face and voice than to gender information. Phonetic information may have a special salience and/or unity that is not apparent in similar but non-phonetic events. The findings are discussed in relation to key theories of perceptual development. / Arts, Faculty of / Psychology, Department of / Graduate

No description available.

The early postnatal period is marked by the rapid acquisition of sensorimotor processing capabilities. Initially responding to a limited set of environmental stimuli with a restricted repertoire of behaviors, mammals exhibit a remarkable proliferation of sensorimotor abilities in the early postnatal period. Central to action selection, reinforcement, and contingency learning are a subcortical set of evolutionarily conserved nuclei called the basal ganglia. The striatum, which is the primary input nucleus of the basal ganglia, receives afferent innervation from throughout the CNS. Its projection neurons (SPNs) integrate these diverse inputs, regulating movement and encoding salient cue-outcome contingencies. Here, using electrophysiological, electrochemical, imaging, and behavioral approaches in mice, I will explore the postnatal maturation of the striatal cholinergic interneuron (ChI), a critical modulator of dopamine signaling, afferent excitation, and SPN excitability. In Chapter 1, I will set the stage for this exploration by reviewing the current literature on striatal postnatal development, including cellular physiology, axonal elaboration and synapse formation, and plasticity expression. I will survey striatal deficits observed in clinical neurodevelopmental conditions such as autism, ADHD, tic disorders, and substance use disorders. I will additionally summarize evidence that the striatum is uniquely vulnerable to physiological and immunological insult, as well as early life adversity. In Chapter 2, I turn my focus specifically to the striatal ChI, uncovering fundamental cell-intrinsic changes that occur postnatally in this population. I will also elaborate on the postnatal maturation of dopamine release properties and regulation thereof by cholinergic signaling from the ChI. In Chapter 3, I investigate the circuit connectivity and circuit-driven firing dynamics of ChIs as they mature postnatally. I utilize a brain slice preparation retaining thalmostriatal afferents in order to assay the ChI pause, a synchronized transient quiescence in ChIs thought to facilitate cue learning and behavioral flexibility. I find that the ChI pause is refined postnatally, dependent on developmental changes in thalamic input strength and the cell- intrinsic expression of specific ionic conductances. Finally, in Chapter 4, I present preliminary evidence that ChI circuit maturation as defined in preceding chapters is delayed by chronic stress exposure postnatally. Following the maternal separation model of early life stress, ChI intrinsic characteristics mature normally, but they retain heightened thalamic innervation and thalamus-driven pause expression.

This study proposed a multifactorial model of development to understand the development of infants during their first 12 months of life who had been born to chemically dependent women. The impact of maternal chemical dependency on pregnancy outcome, factors associated with severity of neonatal abstinence syndrome and effectiveness of three treatments used in the management of neonatal abstinence syndrome was studied in 271 mother-infant pairs, who were managed by the Chemical Dependency Unit, Royal Women’s Hospital, Melbourne between April 1991 and May 1994. / The chemically dependent mothers and their infants were grouped on the basis of their primary drug of abuse: viz methadone, heroin, non-opioid and codeine groups. Fifty two infants born to drug-free mothers were recruited from a routine antenatal clinic of the same hospital to serve as a control group. The controls were matched for maternal age, marital status, race socioeconomic status, educational level, alcohol and tobacco consumption. / Patterns of maternal drug use were determined by reports from methadone treatment programs, drug rehabilitation centres, medical records, personal interviews and urine toxicologic assays performed on mothers during pregnancy and on their infants during the first 48 hours of life. Urine was assayed for metabolites of methadone, amphetamines, barbiturates, cocaine, opiates, cannabis and benzodiazepines. / There were 180 heroin-dependent, one morphine-dependent and one pethidine-dependent pregnant women enrolled in methadone maintenance programs. The methadone group consisted of these 182 methadone-maintained women and their offspring. Thirty five heroin-dependent women and their offspring formed the heroin group. The non-opioid group consisted of 46 chemically dependent women who used multiple drugs but not opioid drugs during their pregnancy and their offspring. There were eight mother-infant pairs in the codeine group. The mothers in this group primarily abused medication containing codeine in pregnancy. (For complete abstract open document)

Rapid and important cerebral developmental changes occur between the third trimester of gestation and the first postnatal months (Sidman and Rakic, 1982). Assessment of these changes in term and preterm infants is of great interest, as it provides insights into early brain development but also how early birth may affect normal brain development (Mewes et al. 2006).<p>Conventional brain magnetic resonance imaging (MRI) is a useful technique to provide structural information on brain development, and several studies have correlated brain structure modifications with specific learning or behavioral problems (Peterson et al. 2003, Woodward et al. 2005, Kapellou et al. 2006, Woodward et al. 2006). Nevertheless, this technique is not sensitive enough to evidence subtle microstructural changes. <p><p>Diffusion tensor imaging (DTI), which assesses and quantifies water diffusion in biological tissues at a microstructural level, may provide unique clues to the structure and geometric organization of the cerebral tissues (Le Bihan et al. 2001). DTI takes advantage of the fact that, in the brain, water molecules diffuse more easily in the direction of the fibers than orthogonally to study cortex and white matter (WM). DTI indices like fractional anisotropy (FA), which expresses the fraction of the magnitude of the diffusion tensor attributable to anisotropic diffusion, mean diffusivity (MD), which corresponds to the directionally averaged magnitude of water diffusion, and longitudinal and transverse diffusivity (λ// and λ⊥), which express respectively the parallel and perpendicular diffusion of water molecules, are used to indirectly quantify brain microstructure and evaluate brain damage (Hüppi et al. 1998, Miller et al. 2002, Ment et al. 2009, Liu et al. 2012). <p><p>Most previously published studies in neonates limited their analysis to particular zones of the WM, using regions of interest (ROI) to select regions where DTI values are expected to change. Approaches on the basis of ROIs have well-known limitations because strong a priori hypotheses about localization and extent of the effects of interest have to be made (Giuliani et al. 2005). Voxel-based methods of neuroimaging data analysis, such as statistical parametric mapping (SPM), do not have such limitations and have been successfully applied to study age-related DTI changes in adults, DTI differences between preterm and infants at term equivalent age, and brain structural asymmetries in infants (Ashtari et al. 2007, Snook et al. 2007, Gimenez et al. 2008, Dubois et al. 2010).<p>Studies correlating DTI indices at term equivalent age with later neurodevelopment are scarce and their analysis is limited to the WM, without exploring the cortex (Arzoumanian et al. 2003). Moreover, they use neuropsychological testing where language evaluation is combined with cognitive and motor scales to give an overall cognitive score (Krishnan et al. 2007, Rose et al. 2007, Rose et al. 2009).<p>The aims of this work were, using a voxel-based analysis of DTI sequences, 1) to evidence new brain regions that experience microstructural modifications along post-menstrual age (PMA) during early development of the human brain, and 2) to correlate regional brain microstructure at term equivalent age with subsequent cognitive, motor and language development at two years corrected age in a population of preterm infants.<p>We first investigated DTI changes in a population of 22 healthy preterm and 6 term infants covering the life period between 34 and 41 weeks PMA, and found that, besides the already-evidenced FA increase in the corticospinal tract (CST) and callosal radiations, the thalami and the thalamic radiations experienced linear microstructural changes. These changes were interpreted as a marker of regression of cytoplasmic arborization and proliferation of immature oligodendrocytes that wrapped around the axons well before the appearance of myelin (Aeby et al. 2009). Then we looked for nonlinear DTI changes, considering that many of biological processes that occur during development follow a nonlinear course. This yielded negative results, probably due to the small sample size. Therefore, in a second study, we searched for regional linear and nonlinear microstructural changes with PMA throughout the brain in a larger population (65 patients) composed exclusively of preterm neonates scanned between 35 and 43 weeks PMA. This study confirmed the linear FA changes with age previously described and, more importantly, evidenced nonlinear changes in brain structures around the right posterior superior temporal sulcus (STS) and in the right lateral occipitotemporal gyrus (LOTG), with FA decrease between 34 and 39 weeks followed by FA increase from 40 weeks to 43 weeks. The right STS belongs to the speech-processing network and is implicated in prosody but also in inter-individual communicative behavior and face processings in close association with the right LOTG. We suggest that the microstructural modifications in brain structures around the right STS and in the LOTG observed between 35 and 43 weeks of gestation in preterm infants could contribute to the functional maturation of these brain regions with increasing age, in a period of life where voices, prosody and faces represent extremely salient stimuli (Aeby et al. 2012).<p>In the second part of the thesis, we tested the hypothesis that abnormal local brain microstructure of preterm infants at term equivalent age would affect neurodevelopmental abilities at age 2 years. Therefore, we searched throughout the whole brain to correlate changes of the Bayley-III scores (cognitive, motor and language composite scores) with the regional distribution of MD, FA, λ// and λ⊥. We found that language abilities are negatively correlated to MD, λ// and λ⊥ in the left superior temporal gyrus (STG) in preterm infants. These findings suggest that higher MD, λ// and λ⊥ values at term- equivalent age in the left STG are associated with poorer language scores in later childhood. Consequently, this highlights the key role of the left STG for the development of language abilities in children and suggests that brain DTI might be an interesting tool to assess on an individual basis the development of language in the preterm.<p><p>To sum up, in this thesis, we showed that, besides the already-evidenced FA increase in the CST and corpus callosum, the thalami and the thalamic radiations experience linear microstructural changes in the early development of the human brain. We further showed that FA changes nonlinearly with age in brain structures around the right STS and in the right LOTG, which are key regions in verbal and non-verbal communicative behavior. We also showed that voxel-based DTI analysis is able to evidence microstructural changes in the lSTG that are negatively correlated with language development at two years in the preterm at the group level. These results highlight the key role of the lSTG in the development of language in the preterm and suggest that brain DTI might be an interesting tool to predict the development of language on an individual basis.<p> / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Pregnant women living in South African peri-urban settlements face many challenges for their health and the health of their infants. Current health care services face many constraints and are not able to meet all the needs of pregnant mothers. Home-visiting programmes implemented by community health workers can alleviate these constraints. The current RCT assessed the effectiveness of the Philani Plus Intervention Program that addressed HIV, alcohol, maternal and child nutrition and mental health. The effectiveness of the intervention was assessed by measuring infant social withdrawal behaviour using the modified Alarm Distress Baby Scale (m- ADBB). A total of 681 cases were randomised into control (N=330) and intervention groups (N=351) and assessed using the m-ADBB. A cut-off score of two and above was used to determined significant social withdrawal behaviour. Data was analysed using descriptive statistics and cross-tabulation initially, followed by analysis of variance and multilevel modelling. Results indicated a prevalence of 46.7% of social withdrawal behaviour; however, no significant differences between groups were found. The current prevalence was substantially higher in comparison to the only other published study using the m-ADBB. Furthermore, the prevalence rate was also significantly higher compared to the majority of other studies using the original Alarm distress Baby Scale (ADBB). The high prevalence of social withdrawal behaviour found in this study indicates an increased risk for suboptimal infant development. Further research regarding social withdrawal behaviour and the casual mechanisms associated with the development of such behaviour is needed. Furthermore, validation of the m-ADBB in different settings is needed. / AFRIKAANSE OPSOMMING: Swanger vroue wat in Suid-Afrikaanse buitestedelike nedersettings woon staar baie uitdagings in die gesig met betrekking tot hul gesondheid en die gesondheid van hul babas. Huidige gesondheidsdienste is baie beperk en is nie in staat om in al die behoeftes van swanger moeders te voorsien nie. Huis-besoek programme wat deur gemeenskaplike gesondheidswerkers geïmplementeer word, kan hierdie beperkings verlig. Die huidige RCT het die effektiwiteit van die Philani Plus Intervensie Program wat MIV, alkohol, voeding en geestelike gesondheid aanspreek, geassesseer. Die effektiwiteit van die intervensie is geassesseer deur sosiale onttrekkingsgedrag met behulp van die gewysigde Alarm Nood Baba Skaal (m-ADBB) te meet. ‘n Totaal van 681 gevalle is lukraak in kontrole (N = 330) en intervensie groepe (N = 351) verdeel en geëvalueer volgens die m-ADBB. 'n Afsnypunt van twee en hoër is gebruik om beduidende sosiale onttrekkingsgedrag te bepaal. Data is aanvanklik ontleed met behulp van beskrywende statistiek en kruis-tabulering, gevolg deur analise van variansie en multi-modelle. Resultate toon 'n 46,7%-voorkoms van sosiale onttrekkingsgedrag, maar het egter geen beduidende verskille tussen groepe getoon nie. Die huidige voorkoms was aansienlik hoër in vergelyking met die enigste ander gepubliseerde studie wat gebruik gemaak het van die m- ADBB. Verder was die voorkomssyfer ook aansienlik hoër in vergelyking met die meerderheid van die ander studies wat gebruik gemaak het van die oorspronklike Alarm Nood Baba Skaal (ADBB). Die hoë voorkoms van sosiale onttrekkingsgedrag dui op 'n verhoogde risiko vir suboptimale baba ontwikkeling. Verdere navorsing oor sosiale onttrekkingsgedrag en die meganismes wat verband hou met die ontwikkeling van sulke gedrag, is nodig. Verder word die bekragtiging van die m-ADBB in verskillende instellings benodig.

This project encompasses program evaluations of infant massage intervention and its impact in the overall development of infants and children born with disabilities or babies born at risk for developmental delays.

MPH / Department of Public Health / See the attached abstract below

Impaired intrauterine growth, inability of the fetus to achieve the required growth potential, contributes to a higher burden of neonatal morbidity and mortality. Intrauterine growth is an inferred process and small for gestational age is considered a rough estimate of impaired intrauterine growth that requires reliable gestational age data. Due to sparse data and measurement errors in gestational age, researchers rely on markers such as birth weight, birth length, and birth head circumference to infer fetal growth. While the etiology of impaired fetal growth is multifactorial, maternal anemia and undernutrition contribute substantially to impaired fetal growth and are prioritized in 2030 global nutrition goals by the World Health Assembly. Nutrition supplements such as lipid-based nutrient supplements, multiple micronutrients, and iron or folic acid during pregnancy are presumed to improve maternal anemia. But the effect of the supplements during pregnancy on fetal growth appears to be small to negligible, which has shifted the researcher’s focus to the pre-conception period. However, prior reviews on the preconception period have either synthesized the evidence from observational studies, or have explored outcomes such as congenital anomalies (e.g., neural tube defects), neurodevelopment disorders, or only birth weight. Hence the evidence from existing randomized controlled trials (RCTs) evaluating the effect of preconception nutrition supplements on maternal anemia and all markers of fetal growth including birth weight, birth length, and birth head circumference has not been systematically summarized and synthesized. We bridged this knowledge gap in the current dissertation (Aim 1). The Women First (WF) Preconception Nutrition Trial found that lipid-based nutrient supplementation started preconception or during pregnancy conferred greater benefits for birth weight and birth length among mothers who were anemic (Hemoglobin (Hb) < 12 g/dL) than among mothers who were non-anemic (Hb ≥ 12 g/dL) pre-pregnancy. However, by dichotomizing women into anemic and non-anemic women, we may miss high-risk women with specific Hb levels who may obtain greater benefits for intrauterine growth associated with the supplements. Assessing the effect of preconception nutrient supplements across a range of pre-pregnancy Hb levels will help us identify women with specific Hb cut-offs who may have the greatest potential to respond to the supplements (Aim 2). Additionally, there are major gaps in understanding the mechanisms of how nutrient supplements, consumed either before or during pregnancy, improve intrauterine growth. A better understanding of the underlying mechanisms would allow for fine-tuning of nutrition interventions for greater efficacy. Here, we examined whether Hb during pregnancy could be a potential mechanism through which nutrition supplements improve intrauterine growth (Aim 3). For Aim 1, we undertook a systematic review and meta-analysis of the RCTs evaluating the effect of preconception nutrition supplements on maternal hemoglobin and markers of intrauterine growth including birth weight, birth length, birth head circumference, and small for gestational age. Additionally, we examined preterm birth as an important perinatal outcome. We searched electronic databases including PubMed, Web of Science, Embase, CINAHL, and Cochrane Central. We computed pooled mean differences and risk ratios (RR) with 95% confidence intervals (CIs) using random-effect models. We employed I2 and Cochran’s Q test statistics to assess heterogeneity. We used the GRADE (grading of recommendations, assessment, development, and evaluations) tool to assess the quality of evidence. For Aim 2 and Aim 3, we leveraged the existing data from a large multi-country Women First (WF) Preconception Nutrition Trial conducted in Pakistan, India, Guatemala, and the Democratic Republic of Congo. Women in the WF trial were randomized to consume a lipid-based nutrient supplement (LNS) at least three months before and during pregnancy (Arm 1- preconception), only during pregnancy (Arm 2- during), or not at all (Arm 3 - control). The outcome was weight, length, and head circumference within 48 hours of birth expressed as Z-scores. For Aim 2, we analyzed the WF trial data on 2443 women-newborn dyads. For each site, we computed adjusted mean differences in these Z-scores between the randomized arms across six pre-pregnancy Hb categories (8-8.9, 9-9.9, 10-10.9, 11-11.9, 12-12.9, and ≥13g/dL) based on Hb distributions. We pooled site-specific effect measures using meta-analysis. For Aim 3, hemoglobin measured at 12 (n=2075) and 32 weeks of gestation (n=2157) was a mediator. We employed causal mediation analysis under a counterfactual approach to estimate direct and indirect effects. For Aim 1, we identified 20 eligible RCTs (n=27,659 women). Preconception nutrition supplements (iron and folic acid, multiple micronutrients, and a lipid-based nutrient supplement) increased maternal hemoglobin by 0.30g/dL ((0.03, 0.57); I2=79%). However, we did not find a significant effect of the supplements on birth weight (12.47gm ((-33.14, 58.08); I2=58%)), birth length (0.15cm (-0.26, 0.56); I2=68%; n=5), birth head circumference (-0.23cm (-0.88, 0.43); I2=84%), small for gestational age (RR: 0.91 (0.80,1.04); I2=31%), or preterm birth (RR: 0.93 (0.69,1.25); I2=57%). Overall, the quality of evidence was assessed as moderate and very low for maternal hemoglobin and three markers of intrauterine growth including birth weight, birth length, and birth head circumference, respectively. In Aim 2, we found that the effect of LNS on birth weight, length, and head circumference varied by pre-pregnancy Hb categories. Pooled mean differences in the Z-scores for birth length (0.60 (0.03, 1.23)), birth weight (0.50, (0.11, 0.89)), and birth head circumference ((0.26, (0.02, 0.51)) were greatest for Arm 1-preconception vs. Arm 3-control women with Hb 9-9.9g/dL. Women with Hb 10-10.9g/dL also benefited from preconception LNS. However, compared to controls, the effects of preconception LNS on birth weight, birth length, and birth head circumference attenuated for women with Hb 10-10.9g/dL. Compared to Arm 3-control, LNS during pregnancy (Arm 2) improved birth length, birth weight, and birth head circumference for women with Hb 8-10.9g/dL. Preconception LNS (Arm1) vs. LNS during pregnancy (Arm 2) improved the three markers of intrauterine growth only for women with Hb 9-9.9g/dL. Women with nearly normal (11-11.9 g/dL) and normal Hb (≥12g/dL) did not appreciably benefit from LNS, offered before and or during pregnancy. For Aim 3, Hb at 12 or 32 weeks of gestation did not mediate the relationship between the LNS and intrauterine growth. Indirect effects of preconception LNS (Arm 1) vs. Arm 3, mediated by Hb at 12 weeks, were 0.02 (-0.02, 0.01), 0.01 (-0.01, 0.02), and 0.01 (-0.01, 0.02) for length, weight, and head circumference Z-scores, respectively. The corresponding direct effects, not mediated by Hb, were 0.18 (0.09, 0.33), 0.12 (0.03, 0.23), and 0.06 (-0.03, 0.20), respectively. Site-specific and gestational age-adjusted data analyses both at 12 and 32 weeks of gestation confirmed the findings of negligible mediation by Hb during pregnancy. All types of preconception nutrition supplements studied to date appear to reduce maternal anemia. However, it is uncertain whether there are beneficial effects of preconception nutrition supplements on markers of intrauterine growth. Low quality of evidence from the RCTs examining the markers of intrauterine growth warrants future well-designed RCTs to produce solid scientific data, particularly on the benefits of a more comprehensive package of preconception nutrition supplements that include both macro- and micronutrients. The findings from the WF trial suggest that the benefits of preconception LNS on fetal growth are mainly confined to women with pre-pregnancy Hb 9-9.9g/dL. Compared to controls, women with Hb 10-10.9g/dL also benefited from preconception LNS, albeit the magnitude of effect on three markers of intrauterine growth was modest for women with Hb 10-10.9g/dL. However, LNS, started during pregnancy, appeared to improve markers of intrauterine growth for women with a wider range of Hb 8-10.9g/dL. Women with Hb ≥ 11g/dL did not benefit from LNS started either pre-conception or during pregnancy. These findings suggest that prioritizing women with specific pre-pregnancy Hb categories for targeted nutrition interventions may be advisable. This would target limited resources most efficiently in LMICs. Lastly, negligible mediation by Hb during pregnancy suggests that alternative pathways that potentially mediate the relationship between LNS and intrauterine growth need to be investigated.

This study aimed at exploring the developmental profile of HIV positive/AIDS infants and children (three to 35 months) over a period of 11 months in the Nelson Mandela Metropole, utilising the Revised Extended Griffiths Scales of Mental Development (GSMD). The purpose was to generate information about the development of HIV positive/AIDS infants and children, highlighting developmental strengths and weaknesses to ultimately aid the custodians of these children with their interventions. A non-probability purposive sampling method was applied, and a longitudinal profile was generated as participants were assessed twice. Participants were all outpatients at Kwazakhele Day Clinic, Dora Nginza and Livingstone Hospitals in the Nelson Mandela Metropole, and were located for the study through their caregiver’s attendance of an HIV support groups at the Dora Nginza Hospital. Data was analysed statistically using descriptive statistics and Hotelings-T² tests. Results indicated a significant difference between first and second assessment on the General Quotient and on two of the six subscales, namely Eye-Hand Co-ordination (D) and Practical Reasoning (F). It was deduced that development declined or did not improve as participants aged.