Language development in children at risk for language impairment: cross-population comparisons

At 3 years of age the spontaneous language of 17 typically developing children was compared to two groups of toddlers who were at risk for language delay for very different reasons. One at-risk group, late talkers, appeared normal in all respects except for their delayed language. These 20 children scored at or below the fifteenth percentile for expressive vocabulary on the MacArthur Communicative Development Inventory (Fenson et al., 1993) when originally identified at 20-27 months of age and within the normal range on the Bayley Scales of Infant Development (Bayley, 1969). The other group, 21 children with unilateral focal brain injury, suffered localized damage to their brain prenatally, perinatally, or within the first 6 months of life. Results indicated that both of the at-risk groups were still significantly lower in vocabulary diversity and grammar at 3 years of age. There was also significantly greater variability in the at-risk groups than in the control groups, and in the children with focal brain injury than in the late talkers in both areas. The importance of language comprehension to development in this period was supported by two findings. First, children with focal brain injury had significantly lower scores than late talkers on the Index of Productive Syntax, a test of emerging grammar, and had been lower in comprehension on a standardized test of language comprehension a year earlier. Second, late talkers with delay in comprehension as well as production had significantly lower scores on IPSyn than those with normal comprehension, suggesting that they are at greater risk for continued delay. Qualitative analyses indicated that the at-risk groups produced the same kinds of errors, but that late talkers produced a substantially greater proportion of errors in obligatory contexts than did children with focal brain injury.     

Role of estrogen in balancing contributions from multiple memory systems

In addition to modulating memory per se, estrogen alters the learning strategy used to solve a task, thereby regulating the quality of information processed by the brain. This review discusses estrogen's actions on cognition within a memory systems framework, highlighting our work with a variety of paradigms showing that learning strategy is sensitive to estrogen even when learning rate is not. Specifically, high levels of gonadal steroids, in particular, elevations in estrogen, bias female rats toward using hippocampal-sensitive approaches while low levels of gonadal steroids promote the use of non-hippocampal sensitive strategies. In light of findings from a variety of approaches involving the hippocampus in allocentric and the striatum in egocentric response patterns, it is likely that estrogen alters the relative participation of these, and most undoubtedly other, neural systems during cognition. Changes in neuromodulators such as acetylcholine that regulate other processes such as inhibitory tone and excitability reflect one mechanism by which estrogen may orchestrate learning and memory.     

Cultural identity, explanatory style, and depression in Navajo adolescents

This study investigated the interrelationships among cultural identity, explanatory style, and depression in Navajo adolescents. A total of 332 (197 female, 135 male) Navajo adolescents completed 7 self-report measures. These data were used to create, via structural equation modeling, a series of factor models and full structural models. Analyses indicated that current factor structures for explanatory style and depression are adequate for use with Navajo adolescents. Increased control and predictability and limited duration of stressful encounters were both predictive of decreased symptoms of depression. Higher levels of Navajo cultural identity had a modest effect in terms of reducing depression. Other factors, such as perceived discrimination and urban/reservation domicile, are important to study to provide an increased understanding of depression among Navajo adolescents.     

Estrogen modulates place learning through estrogen receptors in the hippocampus

Moderate elevations in circulating estradiol enhance learning in tasks that tap place learning strategies such as those requiring the use of extramaze cues. Use of place learning strategies is particularly impaired by damage to the hippocampus, a structure shown to be sensitive to estrogen treatments. We have shown that direct estrogen infusions into the dorsal hippocampus, and not the dorsolateral striatum, enhance place learning, suggesting that the hippocampus may be an important modulatory site for the effects of estrogen on place learning. The current experiment tested whether the hippocampus is indeed a critical site of estrogen modulation through classical estrogen receptors. Young adult female Sprague-Dawley rats were ovariectomized for 21 days and given systemic injections (0.1 ml) of sesame oil (OIL) or 10 microg of 17beta-estradiol-benzoate (E2), 48 and 24 h before being trained on a place task. Twenty-four hours prior to the first systemic injection, separate groups of rats received bilateral hippocampal implants of either the antiestrogen ICI 182,780 (ICI) or cholesterol vehicle. Implants were maintained until and throughout training. Intrahippocampal ICI reversed the enhancement in place learning seen with systemic E2 treatment. Unexpectedly, intrahippocampal ICI in OIL-treated rats also enhanced place learning. These data suggest that ICI may have some mixed agonist and antagonist effects in the hippocampus and that estrogen enhances place learning through activation of estrogen receptors located in the hippocampus.     

Bridges over troubled waters: education and cognitive neuroscience

Recently there has been growing interest in and debate about the relation between cognitive neuroscience and education. Our goal is to advance the debate beyond both recitation of potentially education-related cognitive neuroscience findings and the claim that a bridge between fields is chimerical. In an attempt to begin a dialogue about mechanisms among students, educators, researchers and practitioner-scientists, we propose that multiple bridges can be built to make connections between education and cognitive neuroscience, including teacher training, researcher training and collaboration. These bridges--concrete mechanisms that can advance the study of mind, brain and education--will benefit both educators and cognitive neuroscientists, who will gain new perspectives for posing and answering crucial questions about the learning brain.     

The Collaborative Longitudinal Personality Disorders Study (CLPS): overview and implications

The Collaborative Longitudinal Personality Disorders Study (CLPS; Gunderson et al., 2000) was developed to fill gaps in our understanding of the nature, course, and impact of personality disorders (PDs). Here, we review published findings to date, discuss their implications for current conceptualizations of PDs, and raise questions that warrant future consideration. We have found that PDs are more stable than major depressive disorder, but that meaningful improvements are possible and not uncommon. We have confirmed also that PDs constitute a significant public health problem, with respect to associated functional impairment, extensive treatment utilization, negative prognostic impact on major depressive disorder, and suicide risk. At the same time, we have demonstrated that dimensional models of PDs have clinical validity that categories do not, especially greater temporal stability. Furthermore, dimensional personality traits appear to be the foundation of behaviors described by many PD criteria. Taken together, our results lead us to hypothesize that PDs may be reconceptualized as hybrids of stable personality traits and intermittently expressed symptomatic behaviors.     

Intrahippocampal muscimol shifts learning strategy in gonadally intact young adult female rats

Learning strategy preferences depend upon circulating estrogen levels, with enhanced hippocampus-sensitive place learning coinciding with elevated estrogen levels. The effects of estrogen on strategy may be mediated by fluctuations in GABAergic function, given that inhibitory tone in the hippocampus is low when estrogen is high. We investigated the effects on learning strategy of intrahippocampal injections of a GABA(A) agonist in gonadally intact female rats. On the day of training, rats received 0.3 microL intrahippocampal infusions of muscimol (0.26 nmol or 2.6 nmol) or saline 20 min prior to training on a T-maze in which place (hippocampus-sensitive) or response (striatum-sensitive) strategies offer effective solutions. Muscimol treatment increased the use of the response strategy in a dose-dependent manner without influencing learning speed, indicating that muscimol modulated strategy and not learning ability. Furthermore, the muscimol-related shift to response strategies varied across the estrous cycle. The results indicate that increasing inhibition in the hippocampus biases rats away from hippocampus-sensitive place learning strategies and toward hippocampus-insensitive response learning strategies without a learning deficit. Furthermore, rats at proestrus demonstrated the most dramatic shift in learning strategy following muscimol treatment compared with control conditions, while rats at estrus demonstrated the most complete bias toward response strategies. The enhanced use of hippocampus-sensitive strategies at proestrus likely results from reduced hippocampal inhibition.     

Motion and color processing in school-age children and adults: an ERP study

Stimuli designed to selectively elicit motion or color processing were used in a developmental event-related potential study with adults and children aged 6, 7 and 8. A positivity at posterior site INZ (P-INZ) was greater to motion stimuli only in adults. The P1 and N1 were larger to color stimuli in both adults and children, but earlier to motion stimuli only in adults. Finally, the P2 was larger to color stimuli in adults but larger to motion stimuli in children, and earlier to motion stimuli only in children. The findings across components indicate development from middle childhood to adulthood in aspects of both the motion and color processing systems indexed by this paradigm, but are consistent with an hypothesis of a more protracted time course of development for the motion as compared to the color processing system.     

The effects of spelling consistency on phonological awareness: a comparison of English and German

Within alphabetic languages, spelling-to-sound consistency can differ dramatically. For example, English and German are very similar in their phonological and orthographic structure but not in their consistency. In English the letter a is pronounced differently in the words bank, ball, and park, whereas in German the letter a always has the same pronunciation (e.g., Ball, Park, Bank). It is often argued that reading acquisition has a reciprocal effect on phonological awareness. As reading is acquired, therefore, spoken language representation may be affected differently for English and German children. Prior to literacy acquisition, however, phonological representation in English and German children should be similar due to the similar phonological structure of the two languages. We explored this hypothesis by comparing phonological awareness at the rime and phoneme levels in prereaders and beginning readers in English and German. Similar developmental effects were indeed observed in prereaders, but differential effects had emerged within the first year of reading instruction.     

Gender influences on preschool children's social problem-solving strategies

The authors investigated gender influences on the nature and competency of preschool children's social problem-solving strategies. Preschool-age children (N = 179; 91 boys, 88 girls) responded to hypothetical social situations designed to assess their social problem-solving skills in the areas of provocation, peer group entry, and sharing or taking turns. Results indicated that, overall, girls' responses were more competent (i.e., reflective of successful functioning with peers) than those of boys, and girls' strategies were less likely to involve retaliation or verbal or physical aggression. The competency of the children's responses also varied with the gender of the target child. Findings are discussed in terms of the influence of gender-related social experiences on the types of strategies and behaviors that may be viewed as competent for boys and girls of preschool age.