Multiple-object tracking among individuals with Down syndrome and typically developing children.

We investigated differences in multiple-object tracking among individuals with Down syndrome (DS) as compared to typically developing children matched on a visual-spatial mental age of approximately 5.5 years. In order to ensure that these effects did not originate in differences in encoding or reporting the positions of targets in distracters after a delay, immediate and delayed report were measured for static items. Although their immediate and delayed report for multiple static items was comparable to that of the typically developing children, the participants with DS performed as if they were only capable of tracking a single item at a time regardless of the number of targets that needed to be tracked. This finding is surprising because the operations used in multiple-object tracking are thought to be necessary for visuospatial tasks, which are an area of relative strength among persons with DS. These results call into question the idea that abilities or deficits in multiple-object tracking predict visuospatial performance, and highlight ways that atypical development can inform our understanding of typical development.

Nuclear expression of Rac1 in cervical premalignant lesions and cervical cancer cells.

BACKGROUND: Abnormal expression of Rho-GTPases has been reported in several human cancers. However, the expression of these proteins in cervical cancer has been poorly investigated. In this study we analyzed the expression of the GTPases Rac1, RhoA, Cdc42, and the Rho-GEFs, Tiam1 and beta-Pix, in cervical pre-malignant lesions and cervical cancer cell lines. METHODS: Protein expression was analyzed by immunochemistry on 102 cervical paraffin-embedded biopsies: 20 without Squamous Intraepithelial Lesions (SIL), 51 Low- grade SIL, and 31 High-grade SIL; and in cervical cancer cell lines C33A and SiHa, and non-tumorigenic HaCat cells. Nuclear localization of Rac1 in HaCat, C33A and SiHa cells was assessed by cellular fractionation and Western blotting, in the presence or not of a chemical Rac1 inhibitor (NSC23766). RESULTS: Immunoreacivity for Rac1, RhoA, Tiam1 and beta-Pix was stronger in L-SIL and H-SIL, compared to samples without SIL, and it was significantly associated with the histological diagnosis. Nuclear expression of Rac1 was observed in 52.9% L-SIL and 48.4% H-SIL, but not in samples without SIL. Rac1 was found in the nucleus of C33A and SiHa cells but not in HaCat cells. Chemical inhibition of Rac1 resulted in reduced cell proliferation in HaCat, C33A and SiHa cells. CONCLUSION: Rac1 is expressed in the nucleus of epithelial cells in SILs and cervical cancer cell lines, and chemical inhibition of Rac1 reduces cellular proliferation. Further studies are needed to better understand the role of Rho-GTPases in cervical cancer progression.

Identification with ancestral culture is associated with fewer internalizing problems among older Naskapi adolescents.

The manifestations of externalizing and internalizing behaviors among minority adolescents might best be understood by examining their relation to culturally specific factors, such as cultural identity, as well as to factors that seem to be relevant across cultures, such as age and gender. In this study, we examined the roles of age and gender in moderating the relation between self-reported cultural identity and externalizing and internalizing problems and the interaction between Indigenous and Mainstream cultural identity in relation to problematic behaviors. The participants included 61 students (32 female) with a mean age of 14.5 years (SD = 1.69) from a Naskapi reserve in Quebec, Canada. Age moderated the relation between identification with Indigenous culture and internalizing symptomatology. Indigenous and Mainstream cultural identity did not interact in predicting internalizing or externalizing problems. Consistent with the available evidence regarding the centrality of identity in adolescent development, the magnitude of the inverse relation between identification with Indigenous culture and number of clinical internalizing symptoms appears to increase in significance later in adolescence. The lack of an interaction between Indigenous and Mainstream cultural identity in relation to internalizing and externalizing problems suggests that it is the need to consider both cultures individually without the assumption that one negates the other.

Constructions and deconstructions of risk, resilience and wellbeing: a model for understanding the development of Aboriginal adolescents.

A developmental framework for understanding issues of risk, resilience, and wellness among Aboriginal adolescents in Canada and elsewhere is presented. As these constructs are not monolithic, simplistic linear risk models of a specific predictor to a specific outcome are inadequate to conceptually capture the complexities of real-life patterns. Accordingly, the conceptual focus is on ideal constructions of competence within the context of continually ongoing transactions in which the adolescents effect and are effected by the various layers and components of the environment. However, the pragmatics of empirical research necessitate simpler approaches in which outcomes are predicted from specific factors. Nonetheless, in keeping with the notion of the complexity of all individuals, competence and wellness are viewed within the framework of the 'whole child' across domains of academic success, behavioural competence and appropriateness, social adaptation, and emotional health within the context of the specific community. Although Aboriginal communities within Quebec, across Canada, the United States and elsewhere, differ considerably with regard to history, culture, language, and priorities for its youth, this approach allows for the universal application of a framework, for which specifics can be modified in relation to the unique and changing aspects of societies, communities, and the individuals within.

Time estimation among low-functioning individuals with autism spectrum disorders: evidence of poor sensitivity to variability of short durations.

Time estimation of short durations (under 1 sec) was examined in low-functioning individuals with autism spectrum disorder (ASD) and typically developing (TD) children matched on mental age. Temporal bisection and generalization tasks were used to examine basic perceptual timing mechanisms. For both tasks, the participants with ASD demonstrated less sensitivity to variability in short durations than the TD children, adding to a growing body of literature suggesting deficits in timing exist for longer durations. The results highlight the need to examine multiple levels of processing of time-related information from basic perceptual mechanisms to higher level cognitive mechanisms.

Cognitive flexibility among individuals with Down syndrome: assessing the influence of verbal and nonverbal abilities.

The influences of verbal mental age (VMA) and performance mental age (PMA) on cognitive flexibility were examined among a group of participants with Down syndrome (DS), in order to disentangle the relative contributions of each. The impaired cognitive flexibility typically observed among individuals with DS in combination with uneven VMA and PMA development suggests an opportunity to further understand the developmental relationship between VMA, PMA, and cognitive flexibility. We examined the performance of 22 participants with DS on the Flexible Item Selection Task (FIST), used for measuring cognitive flexibility among preschoolers. Partial correlations revealed that only VMA was related to the FIST after controlling for PMA, highlighting the role of verbal abilities in the development of cognitive flexibility.

Cultural mismatch and the education of Aboriginal youths: the interplay of cultural identities and teacher ratings.

In response to the enduring "deficit" approach to the educational attainment of Aboriginal students in North America, we hypothesized that academic underperformance is related to a cultural mismatch between Aboriginal students' cultural background, which emphasizes connectedness and interdependence, and the mainstream White model of education, which focuses on independence and assertiveness. The participants included virtually all the secondary students (N = 115) in the Naskapi community of Kawawachikamach, Quebec, Canada. We obtained self-reports of identification with Aboriginal and White culture, teacher reports of assertiveness, and official grades. We found that high identification with either Aboriginal or White culture was related to higher grades, regardless of whether the students were perceived as assertive by their teacher. Conversely, at low levels of cultural identification toward Aboriginal or White culture, being perceived as low in assertiveness by one's teacher predicted lower grades. This suggests that both high cultural identification and assertiveness can contribute to enhancing the educational outcomes of Aboriginal students, but that Aboriginal students with low levels of both cultural identification and assertiveness are at particular risk as they are mismatched with the culture of mainstream schools and do not benefit from the protective effects of identity. The relationships among identity, cultural values, and academic performance point to the need to reject the notion of an inherent deficit in education among Aboriginal youths in favor of a different framework in which success can be attained when alternative ways of being are fostered and nurtured in schools.