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- All Subjects: psychology
Social influences are important determinants of drug initiation in humans, particularly during adolescence and early adulthood. My dissertation tested three hypotheses: 1) conditioned and unconditioned nicotine and social rewards elicit unique patterns of neural signaling in the corticolimbic neurocircuitry when presented in combination versus individually; 2) play behavior is not necessary for expression of social reward; and 3) social context enhances nicotine self-administration. To test the first hypothesis, Fos protein was measured in response to social and nicotine reward stimuli given alone or in combination and in response to environmental cues associated with the rewards in a conditioned place preference (CPP) test. Social-conditioned environmental stimuli attenuated Fos expression in the nucleus accumbens core. A social partner elevated Fos expression in the caudate-putamen, medial and central amygdala, and both nucleus accumbens subregions. Nicotine decreased Fos expression in the cingulate cortex, caudate-putamen, and the nucleus accumbens core. Both stimuli combined elevated Fos expression in the basolateral amygdala and ventral tegmental area, suggesting possible overlap in processing both rewards in these regions. I tested the second hypothesis with an apparatus containing compartments separated by a wire mesh barrier that allowed limited physical contact with a rat or object. While 2 pairings with a partner rat (full physical contact) produced robust CPP, additional pairings were needed for CPP with a partner behind a barrier or physical contact with an object (i.e., tennis ball). The results demonstrate that physical contact with a partner rat is not necessary to establish social-reward CPP. I tested the third hypothesis with duplex operant conditioning chambers separated either by a solid or a wire mesh barrier to allow for social interaction during self-administration sessions. Nicotine (0.015 and 0.03 mg/kg, IV) and saline self-administration were assessed in male and female young-adult rats either in the social context or isolation. Initially, a social context facilitated nicotine intake at the low dose in male rats, but suppressed intake in later sessions more strongly in female rats, suggesting that social factors exert strong sex-dependent influences on self-administration. These novel findings highlight the importance of social influences on several nicotine-related behavioral paradigms and associated neurocircuitry.
The present study utilized longitudinal data from a high-risk community sample (n=254, 52.8% female, 47.2% children of alcoholics, 74% non-Hispanic Caucasian) to test questions concerning the effects of genetic risk, parental knowledge, and peer substance use on emerging adult substance use disorders (SUDs). Specifically, this study examined whether parental knowledge and peer substance use mediated the effects of parent alcohol use disorder (AUD) and genetic risk for behavioral undercontrol on SUD. The current study also examined whether genetic risk moderated effects of parental knowledge and peer substance use on risk for SUD. Finally, this study examined these questions over and above a genetic "control" which explained a large proportion of variance in the outcome, thereby providing a stricter test of environmental influences.
Analyses were performed in a path analysis framework. To test these research questions, the current study employed two polygenic risk scores. The first, a theory-based score, was formed using single-nucleotide polymorphisms (SNPs) from receptor systems implicated in the amplification of positive effects in the presence of new/exciting stimuli and/or pleasure derived from using substances. The second, an empirically-based score, was formed using a data-driven approach that explained a large amount of variance in SUDs. Together, these scores allowed the present study to test explanations for the relations among parent AUD, parental knowledge, peer substance use, and SUDs.
Results of the current study found that having parents with less knowledge or an AUD conferred greater risk for SUDs, but only for those at higher genetic risk for behavioral undercontrol. The current study replicated research findings suggesting that peer substance use mediated the effect of parental AUD on SUD. However, it adds to this literature by suggesting that some mechanism other than increased behavioral undercontrol explains relations among parental AUD, peer substance use, and emerging adult SUD. Taken together, these findings indicate that children of parents with AUDs comprise a particularly risky group, although likelihood of SUD within this group is not uniform. These findings also suggest that some of the most important environmental risk factors for SUDs exert effects that vary across level of genetic propensity.
Discrimination in Mexican American adolescents: : examining processes that minimize negative adjustment outcomes
Recent reports have indicated that there are both mental health and educational disparities between Latino youth and their European American counterparts. Specifically, Latin youth are at a heightened risk for negative mental health outcomes in comparison to their non-Latino youth (e.g., Eaton et al., 2008). Further, 16.7% of Latino adolescents dropped out of high school compared to 5.3% of European American youth over the past several decades (1960-2011; U.S. Department of Education, 2013). Mexican American (M.A. youth in particular, have the lowest educational attainment among all Latino ethnic groups in the U.S. (U.S. Census Bureau, 2010). While these mental health and educational disparities have often been attributed to discrimination experiences that Latino youth encounter, there is also consistent empirical evidence linking discrimination with these maladjustment problems. These studies confirmed that discrimination directly related to depressive symptoms (e.g., Umana-Taylor et al., 2007), externalizing behaviors (Berkel et al., 2010), self-esteem (e.g., Zeiders et al., 2013), and academic outcomes (e.g., Umana-Taylor et al., 2012). Few studies to date have examined the underlying mechanisms (i.e., moderation and mediation) that help us to better understand resiliency paths for those Latino youth that display positive adjustment outcomes despite being faced with similar discrimination encounters that their maladjusted peers face. Therefore, the following two studies examined various mechanisms in which discrimination related to adjustment to better understand potential risk and resiliency processes in hopes of informing intervention research. Paper 1 explored cultural influences on the association between discrimination, active coping, and mental health outcomes in M.A. youth. Paper 2 examined how trajectories of discrimination across 5th, 7th, and 10th grades related to cultural values, externalizing behaviors, and academic outcomes in M.A. youth. Taken together, these studies provide a culturally informed overview of adjustment processes in M.A. adolescents who face discrimination in addition to identifying critical directions for future research in efforts to gaining a more contextualized and comprehensive understanding of the dynamic processes involved in discrimination and adjustment in M.A. youth.
While the cross-cultural literature on body dissatisfaction among Mexican and Mexican-American women has continued to grow, the traditional Latino female gender role of marianismo, sociocultural factors related to ethnic culture and mainstream/American culture ideal perceived discrepancies in body size, and one’s romantic relationship have not been explored with this population in relationship to body satisfaction. The current study included 227 female participants predominantly from a large southwestern university in the United States and a large university in northern Mexico. The study examined differences in marianismo and body satisfaction between 120 Mexican and 107 Mexican-American women, investigated the role of marianismo as a mediator between weight-related teasing and body satisfaction, and explored the relationship between marianismo, Partner Ideal Discrepancy, Ethnic Culture Ideal Discrepancy, Mainstream/American Culture Ideal Discrepancy, Perceived Weight-Related Criticism/Teasing, Relationship Support, Relationship Depth, and Relationship Conflict to overall body satisfaction. Results indicated Mexican-American women endorsed less overall body satisfaction than did their Mexican counterparts suggesting that Mexican American women may be more influenced by societal messages about thinness and beauty than are Mexican women. The findings also revealed a possible trend for marianismo as a mediator between weight-related criticism and body satisfaction. Marianismo and weight-related teasing were found to have a negative relationship with body satisfaction. Multiple regression analyses revealed that Partner Ideal and Mainstream/American Culture Ideal discrepancies accounted for significant variance in body satisfaction. Relationship Conflict accounted for a smaller but still significant amount of the variance in body satisfaction. Ethnic Culture Discrepancy, Relationship Support, and Relationship Depth were not significant predictors. These findings from this study suggest that both cultural variables and romantic relationship variables are related to the body image of Mexican American and Mexican women. These findings have important implications for the adaptation of current etiological models explaining body satisfaction among Mexican and Mexican-American women as well as highlighting the need to consider the role of both cultural and relationship variables in designing clinical interventions for Mexican American and Mexican women coping with body image concerns.
Currently, there is a clear gap in the missing data literature for three-level models.
To date, the literature has only focused on the theoretical and algorithmic work
required to implement three-level imputation using the joint model (JM) method of
imputation, leaving relatively no work done on fully conditional specication (FCS)
method. Moreover, the literature lacks any methodological evaluation of three-level
imputation. Thus, this thesis serves two purposes: (1) to develop an algorithm in
order to implement FCS in the context of a three-level model and (2) to evaluate
both imputation methods. The simulation investigated a random intercept model
under both 20% and 40% missing data rates. The ndings of this thesis suggest
that the estimates for both JM and FCS were largely unbiased, gave good coverage,
and produced similar results. The sole exception for both methods was the slope for
the level-3 variable, which was modestly biased. The bias exhibited by the methods
could be due to the small number of clusters used. This nding suggests that future
research ought to investigate and establish clear recommendations for the number of
clusters required by these imputation methods. To conclude, this thesis serves as a
preliminary start in tackling a much larger issue and gap in the current missing data
Social support from family and friends and their role as buffers against internalizing symptoms among Mexican American youth
Internalizing symptoms are prevalent among adolescents, especially among Latinos, and can have negative consequences on health and development. Understanding the risk and protective factors leading to internalizing difficulties among Latino youth is critical. The current study sought to assess the effects of family risk and peer social rejection in the seventh grade on internalizing symptoms in the tenth grade, and the potential buffering effects of social support from family and from friends, among a sample of 749 Mexican American youth. Structural equation modeling was used to examine pathways from seventh grade family risk and peer social rejection to internalizing symptoms in the tenth grade. Perceived social support from family and perceived social support from friends were tested as moderators of these relations. Gender differences in these pathways were also assessed. Results showed that family risk did not predict tenth grade internalizing symptoms, but that peer social rejection predicted increased internalizing symptoms for girls. Furthermore, buffering effects were not confirmed; rather social support from both friends and family had no effect on the relation between family risk and internalizing symptoms, and high levels of social support from both sources amplified the effect of peer social rejection on internalizing symptoms. Secondary analyses suggested that at low levels of social support from both sources, peer social rejection predicted decreased internalizing symptoms for males. Limitations and implications for prevention and future research are discussed.
The Influence of maternal prenatal stress and emotion socialization on infant emotion expression: differentiating positive and negative trajectories
The first half-year of infancy represents a salient time in which emotion expression assumes a more psychological character as opposed to a predominantly physiological one. Although previous research has demonstrated the relations between early parenting and later emotional competencies, there has been less of a focus on differentiating positive and negative emotion expression across the early infancy period. Thus, the current study investigates the growth of positive and negative emotion expression across early infancy in a low-income, Mexican-American sample, and examines the development of emotion expression as a function of early maternal emotion socialization and prenatal stress. Participants included 322 mothers and their infants. Data were collected in participants' homes prenatally and when the infants were 12-, 18-, and 24-weeks old. Mothers were asked to interact with their infants in a semi-structured teaching task, and video-taped interactions of mother and infant behaviors were then coded. Data for mothers was collected at the prenatal and 12-week visits and data for infants was collected at the 12-, 18-, and 24-week visits. Prenatal stress was measured via two questionnaires (Daily Hassles Questionnaire and Perceived Stress Scale). Maternal socialization at 12 weeks was represented as a composite of four observational codes from the Coding Interactive Behavior coding system. Infant emotion expression was also globally rated across the 5-minute teaching task. Findings suggest that the normative development of emotion expression across early infancy is complex. Positive emotion expression may increase across the early infancy period whereas negative emotion expression decreases. Further, at 12 weeks, greater maternal emotion socialization relates to more infant positivity and less negativity, in line with current conceptualization of parenting. However, across time, greater early socialization predicted decreased positivity and was unrelated to negative emotion expression. Findings also suggest that prenatal stress does not relate to socialization efforts or to infant emotion expression. A better understanding of the nuanced development of positive and negative emotion development as a function of early parenting may have implications for early intervention and prevention in this high-risk population.
The International Standards Organization (ISO) documentation utilizes Fitts’ law to determine the usability of traditional input devices like mouse and touchscreens for one- or two-dimensional operations. To test the hypothesis that Fitts’ Law can be applied to hand/air gesture based computing inputs, Fitts’ multi-directional target acquisition task is applied to three gesture based input devices that utilize different technologies and two baseline devices, mouse and touchscreen. Three target distances and three target sizes were tested six times in a randomized order with a randomized order of the five input technologies. A total of 81 participants’ data were collected for the within subjects design study. Participants were instructed to perform the task as quickly and accurately as possible according to traditional Fitts’ testing procedures. Movement time, error rate, and throughput for each input technology were calculated.
Additionally, no standards exist for equating user experience with Fitts’ measures such as movement time, throughput, and error count. To test the hypothesis that a user’s experience can be predicted using Fitts’ measures of movement time, throughput and error count, an ease of use rating using a 5-point scale for each input type was collected from each participant. The calculated Mean Opinion Scores (MOS) were regressed on Fitts’ measures of movement time, throughput, and error count to understand the extent to which they can predict a user’s subjective rating.
This study examines the effects of providing persuasive writing and reading comprehension strategy training on source-based essay writing. Strategy training was administered through the use of the Writing Pal and the Interactive Strategy Trainer for Active Reading and Thinking (iSTART). The impact of both individual (writing or reading) and blended strategy training on source-based writing was investigated. A total of 261 participants completed the study; after removing incomplete and second language participants the source-based writing and system performance was assessed for 175 participants (n no instruction = 48, n iSTART =41, n Writing Pal =41, n blended =45).
Results indicated that participants who received blended strategy training produced higher quality source-based essays than participants who received only reading comprehension, writing strategy training, or no training. Furthermore, participants who received only reading comprehension or writing strategy training did not produce higher quality source-based essays than participants in the no-training control group. Time on task was investigated as a potential explanation for the results. Neither total time on task nor practice time were predictive of group differences on source-based essay scores. Analyses further suggested that the impact of strategy training does not differ as a function of prior abilities; however, training does seem to impact the relation between prior abilities and source-based essay scores. Specifically, prior writing ability was unrelated to performance for those who received writing training (i.e., Writing Pal and blended conditions), and prior reading ability was unrelated to performance for those received the full dosage of iSTART training. Overall, the findings suggest that when taught in conjunction with one another, reading comprehension and writing strategy training transfers to source-based writing, providing a positive impact on score. Potential changes to the Writing Pal and iSTART to more closely align training with source-based writing are discussed as methods of further increasing the impact of training on source-based writing.
Cognitive changes across the menopause transition: a longitudinal evaluation of the impact of age and ovarian status on spatial memory
Aging and the menopause transition are both intricately linked to cognitive changes
during mid-life and beyond. Clinical literature suggests the age at menopause onset can differentially impact cognitive status later in life. Yet, little is known about the relationship between behavioral and brain changes that occur during the transitional stage into the post-menopausal state. Much of the pre-clinical work evaluating an animal model of menopause involves ovariectomy in rodents; however, ovariectomy results in an abrupt loss of circulating hormones and ovarian tissue, limiting the ability to evaluate gradual follicular depletion. The 4-vinylcyclohexene diepoxide (VCD) model simulates transitional menopause in rodents by selectively depleting the immature ovarian follicle reserve and allowing animals to retain their follicle-deplete ovarian tissue, resulting in a profile similar to the majority of menopausal women. Here, Vehicle or VCD treatment was administered to ovary-intact adult and middle-aged Fischer-344 rats to assess the cognitive effects of transitional menopause via VCD-induced follicular depletion over time, as well as to understand potential interactions with age, with VCD treatment beginning at either six or twelve months of age. Results indicated that subjects that experience menopause onset at a younger age had impaired spatial working memory early in the transition to a follicle-deplete state. Moreover, in the mid- and post- menopause time points, VCD-induced follicular depletion amplified an age effect, whereby Middle-Aged VCD-treated animals had poorer spatial working and reference memory performance than Young VCD-treated animals. Correlations suggested that in middle age, animals with higher circulating estrogen levels tended to perform better on spatial memory tasks. Overall, these findings suggest that the age at menopause onset is a critical parameter to consider when evaluating learning and memory across the transition to reproductive senescence. From a translational perspective, this study informs the field with respect to how the age at menopause onset might impact cognition in menopausal women, as well as provides insight into time points to explore for the window of opportunity for hormone therapy during the menopause transition to attenuate age- and menopause- related cognitive decline, and produce healthy brain aging profiles in women who retain their ovaries throughout the lifespan.