The mobile conjugate reinforcement paradigm in a lab setting.

The mobile conjugate reinforcement task was administered to 4-month-old infants in a lab rather than a home setting where it is usually administered. Learning and retention patterns were comparable to those of infants tested in their homes, suggesting flexibility in where this task can be administered. These results pave the way for this task to be used with a broader range of infants for whom home visits are not practical or convenient (e.g., infants in child care). Developmental research conducted with a more diverse population of infants would facilitate our understanding of cognitive development very early in life.

Higher maternal prenatal cortisol and younger age predict greater infant reactivity to novelty at 4 months: an observation-based study.

Distress-linked activation of the maternal hypothalamic-pituitary-adrenal (HPA)-axis is considered a pathway by which affect regulation impacts the fetal milieu and neurodevelopment. There is little direct evidence for this conceptual model. In 103 women [mean age 27.45 (±5.65) years] at 36-38 weeks gestation, salivary cortisol was measured before/after stress tasks; distress questionnaires were completed. At 18.49 (±1.83) weeks, infants underwent the Harvard Infant Behavioral Reactivity Protocol assessing cry/motor responses to novelty; women reported on infant behavior and postnatal distress. Prenatal cortisol and distress were not significantly correlated (all ps > .10). Proportional odds logistic regressions showed that neither prenatal nor postnatal distress was associated with infant responses to the Harvard Protocol yet pre-stress cortisol and maternal age were: The odds of being classified as High Reactive were 1.60 times higher [95% CI: 1.04, 2.46] for each unit of added cortisol and .90 times lower [95% CI: .82, .99] for every additional year in maternal age. No associations were found between cortisol or prenatal distress and mother-rated infant behavior; postnatal distress was positively associated with mother-rated infant negative behavior (p = .03). Observer and mother-rated infant behavior were not associated (all ps > .05). Based on independent observations of infants in contrast to maternal perceptions, these results lend support to the hypothesis that pregnant women's HPA-axis activity influences infant behavior. The impact of maternal distress was not supported, except in so far as postnatal distress may increase the likelihood of making negative judgments about infant behavior.

Associations between different dimensions of prenatal distress, neonatal hippocampal connectivity, and infant memory.

Prenatal maternal distress-an umbrella concept encompassing multiple negative psychological states including stress, anxiety, and depression-is a substantial prenatal exposure. Consistent across preclinical and human studies, the hippocampus displays alterations due to prenatal distress. Nevertheless, most prenatal distress studies do not focus on multiple dimensions of, have not examined hippocampal functional connectivity in association with, and do not consider observer-based functional outcomes related to distress. We investigated the effects of different dimensions of prenatal distress in pregnant adolescents, a population at high risk for distress, in association with neonatal hippocampal connectivity and infant memory. In pregnant adolescents (n = 42), we collected four measures of distress (perceived stress, depression, pregnancy-specific distress, and 24-h ambulatory salivary cortisol) during the 2nd and 3rd trimesters. Resting-state imaging data were acquired in their infants at 40-44 weeks post-menstrual age. Functional connectivity was measured from hippocampal seeds. Memory abilities were obtained at 4 months using the mobile conjugate reinforcement task. Shared across different dimensions of maternal distress, increased 3rd trimester maternal distress associated with weaker hippocampal-cingulate cortex connectivity and stronger hippocampal-temporal lobe connectivity. Perceived stress inversely correlated while hippocampal-cingulate cortex connectivity positively correlated with infant memory. Increased cortisol-collected during the 2nd, but not the 3rd, trimester-associated with weaker hippocampal-cingulate cortex connectivity and stronger hippocampal-temporal lobe connectivity. Different dimensions of prenatal maternal distress likely contribute shared and unique effects to shaping infant brain and behavior.

Neonatal brain metabolite concentrations: Associations with age, sex, and developmental outcomes.

Age and sex differences in brain metabolite concentrations in early life are not well understood. We examined the associations of age and sex with brain metabolite levels in healthy neonates, and investigated the associations between neonatal brain metabolite concentrations and developmental outcomes. Forty-one infants (36-42 gestational weeks at birth; 39% female) of predominantly Hispanic/Latina mothers (mean 18 years of age) underwent MRI scanning approximately two weeks after birth. Multiplanar chemical shift imaging was used to obtain voxel-wise maps of N-acetylaspartate (NAA), creatine, and choline concentrations across the brain. The Bayley Scales of Infant and Toddler Development, a measure of cognitive, language, and motor skills, and mobile conjugate reinforcement paradigm, a measure of learning and memory, were administered at 4 months of age. Findings indicated that postmenstrual age correlated positively with NAA concentrations in multiple subcortical and white matter regions. Creatine and choline concentrations showed similar but less pronounced age related increases. Females compared with males had higher metabolite levels in white matter and subcortical gray matter. Neonatal NAA concentrations were positively associated with learning and negatively associated with memory at 4 months. Age-related increases in NAA, creatine, and choline suggest rapid development of neuronal viability, cellular energy metabolism, and cell membrane turnover, respectively, during early life. Females may undergo earlier and more rapid regional developmental increases in the density of viable neurons compared to males.

Image-dependent interaction of imagery and vision.

The influence of imagery on perception depends on the content of the mental image. Sixty-three students responded to the location of the 2 hands of a clock while visualizing the correct or an incorrect clock. Reaction time was shorter with valid cueing. Could this have resulted from visual acquisition strategies such as planning visual saccades or shifting covert attention? No. In this study, a crucial control condition made participants look at rather than visualize the cue. Acquisition strategies should have affected equally both types of cueing, but we observed that the effect of the visual cue was smaller and limited to a particular subcase in which one expects visual acquisition strategies. Thus, what matters is the similarity of the content of the mental image with the visual scene. In addition, an interaction involving the hand used for responding supports the notion that composite imagery is lateralized.

Basic-level nouns: first learned but misunderstood.

It is commonly believed that first-learned words correspond with first-learned categories (both described as 'basic level') leading to the belief that language acquisition is a reasonably good indicator of early cognition. However, toddlers often overextend their first words. Do these errors reflect their comprehension? Two experiments were conducted in order to examine two-year-olds' production and comprehension of basic-level terms. The results showed overextensions both in production (e.g. children labelled a rocket 'airplane') and comprehension (e.g. they pointed to a rocket when airplane was requested). One reason toddlers extend labels to a wider conceptual domain is because they have not clearly differentiated basic-level concepts from related conceptual categories.

Understanding spatial relations: flexible infants, lexical adults.

Concepts of containment, support, and degree of fit were investigated using nonverbal, preferential-looking tasks with 9- to 14-month-old infants and adults who were fluent in either English or Korean. Two contrasts were tested: tight containment vs. loose support (grammaticized as 'in' and 'on' in English by spatial prepositions and 'kkita' and 'nohta' in Korean by spatial verbs) and tight containment vs. loose containment (both grammaticized as 'in' in English but separately as 'kkita' and 'nehta' in Korean). Infants categorized both contrasts, suggesting conceptual readiness for learning such spatial semantics in either language. English-speaking adults categorized tight containment vs. loose support, but not tight vs. loose containment. However, Korean-speaking adults were successful at this latter contrast, which is lexicalized in their language. The adult data suggest that some spatial relations that are salient during the preverbal stage become less salient if language does not systematically encode them.