Browsing by Subject "Individual differences"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    BEHAVIORAL PREDICTORS OF INDIVIDUAL DIFFERENCES IN OPIOID ADDICTION VULNERABILITY
    (2021-04) Swain, Yayi
    Understanding behavioral predictors of individual differences in opioid addiction vulnerability could provide critical insights into the mechanisms underlying opioid addiction and could lead to more effective treatments. However, very few behavioral predictors of individual differences in opioid self-administration (SA), a key preclinical model of opioid addiction, have been established. The goal of this dissertation was to evaluate several potential behavioral predictors of individual differences in morphine SA in rats, and to establish novel methodologies for studying opioid addiction vulnerability using the SA paradigm. Study 1 showed that spontaneous locomotor activity in a novel environment, an animal model of sensation-seeking that predicts SA of several drugs of abuse (e.g., stimulants), did not predict individual differences in morphine SA. Study 2 found that greater severity of anhedonia-like behavior during withdrawal from acute morphine exposure (withdrawal-induced anhedonia, WIA) predicted subsequent lower acquisition, demand, and reinstatement of morphine SA. Study 3 showed the feasibility of using regularized factor analysis on morphine SA measures, and revealed that a common latent factor underlies four separate measures of morphine SA. Additionally, while acquisition, demand and morphine-induced reinstatement associated closely with the common latent Addiction factor, stress-induced reinstatement did not. Overall, these studies extended the opioid individual differences literature by establishing WIA as one of the first behavioral predictors of opioid SA, and also expanded the range of analytical tools to be utilized in preclinical behavioral studies.
  • Thumbnail Image
    Item
    Effects of Genes on Individual Differences in Executive Function Development in Preschool-Aged Children
    (2015-04-22) Sherman, Samantha J.; Hodel, Amanda S.; Markant, Julie C.; Thomas, Kathleen M.
    Few studies have examined how individual differences in genes related to the brain’s dopamine system impact the development of higher-level cognitive skills in children. Past research with adults has identified that variants of the dopamine transporter gene (DAT-1) are associated with poorer inhibitory control development, including higher impulsivity and risk-taking. Similarly, genetic variability related to COMT, an enzyme that degrades dopamine, predicts working memory abilities in adults. This study evaluated whether individual differences in the DAT-1 VNTR polymorphism and COMT Val158Met polymorphism predicted the development of executive functions (higher order cognitive skills, including working memory, inhibitory control, and attention shifting) at age 5. On tasks requiring inhibitory control (balloon analogue risk task, delay discounting), we found a non-significant relationship between children’s performance and DAT-1 VNTR genotypes. On tasks examining working memory (spatial span, memory search), children homozygous for the Met allele of the COMT Val158Met polymorphism performed more poorly than their peers with a Val allele. Parent report of inhibitory control and working memory development was unrelated to children’s genotypes, highlighting that differences by genotype are not within the clinical range of abnormality. Overall, our results suggest that the COMT polymorphism is associated with similar effects on preschooler’s working memory abilities as reported in adult studies. However, neither DAT-1 VNTR polymorphism predicted inhibitory control development at preschool age, suggesting that additional environmental factors may have a stronger impact on inhibitory control during early childhood.
  • Thumbnail Image
    Item
    The effects of questioning during and after reading on inference generation between skilled and less-skilled comprehenders.
    (2011-09) Carlson, Sarah Elizabeth
    Reading comprehension involves several cognitive factors during and after reading and differs between readers with different comprehension skills. The purpose of this study was to examine cognitive factors, specifically inference generation, during and after reading between skilled and less-skilled comprehenders. Additionally, other cognitive factors may influence skilled and less-skilled comprehenders' inference generation, and working memory (WM) may be a potential factor. A review of the adult-focused and children-focused literature for the research and theories in inference generation, WM, and comprehension skill are presented. Participants in this study included 61 third- through fifth-grade skilled and less-skilled comprehenders. Inference generation was examined during and after reading using a causal questioning technique and sentence verification task (SVT). Responses from recall were also collected to assess comprehension of the texts used in this study, and WM was examined as a moderator variable. Overall, there was an effect of questioning on some types of inferences generated and recall for skilled and less-skilled comprehenders, and WM appeared to moderate inference generation for skilled-comprehenders; however, there was no effect of type of comprehender on SVT responses. These findings are discussed in terms of maintaining local and global coherence during and after reading in order to develop a coherent representation of a text; updating after reading; and the role of WM during inference generation between skilled and less-skilled comprehenders.
  • Thumbnail Image
    Item
    Free will, determinism, and intuitive judgments about the heritability of behavior
    (2019-09) Willoughby, Emily
    The fact that genes and environment contribute differentially to variation in human behaviors, traits and attitudes is central to the field of behavior genetics. Perceptions about these differential contributions may affect ideas about human agency. We surveyed two independent samples (N = 301 and N = 740) to assess beliefs about free will, determinism, political orientation, and the relative contribution of genes and environment to 21 human traits. We find that lay estimates of genetic influence on these traits cluster into four distinct groups, which differentially predict beliefs about human agency, political orientation, and religiosity. Despite apparent ideological associations with these beliefs, the correspondence between mean lay estimates and published heritability estimates for the surveyed traits is large (r = .77). Belief in genetic determinism emerges as a modest predictor of accuracy in these lay estimates. Additionally, educated mothers with multiple children emerge as particularly accurate in their estimates of the genetic contribution to these traits.
  • Thumbnail Image
    Item
    A rodent model of phenotypic variation in sweet preference, addiction vulnerability, and pharmacological treatment sensitivity
    (2013-01) Holtz, Nathan Alexander
    Sweet preference is a stable, genetically-mediated trait that is associated with vulnerability to drug dependence in both human and non-human animals. For instance, rats that have been selectively bred for high intake of a saccharin solution (HiS) are more drug-prone than rats bred for low saccharin intake (LoS). The experiments detailed in this review investigated whether the HiS and LoS phenotypes would display differential effects of pharmacological agents on cocaine self-administration and cocaine-seeking behavior. Treatment effects (e.g., baclofen, progesterone, allopregnanolone, or histamine) were examined between the HiS and LoS rats during the following phases: escalation during long access (LgA) to the drug [Experiments 1 (baclofen) and 3 (progesterone)], including pre- and post-escalation short-access (ShA) periods, dose-response assessment, and cocaine-primed reinstatement of extinguished drug-seeking behavior [Experiments 2 (baclofen) and 4 (allopregnanolone)]. The last experiment investigated the effect of pharmacological treatment of steady-state cocaine self-administration; specifically, we used a punishment paradigm in which histamine was added to the i.v. cocaine self-administration solution (Experiment 5). We found that baclofen and progesterone decreased cocaine intake in LoS animals but increased cocaine intake in HiS animals. Baclofen attenuated cocaine-primed reinstatement of drug-seeking behavior in both HiS and LoS rats equally. In contrast, allopregnanolone potentiated low-dose cocaine-primed reinstatement in LoS rats, whereas it attenuated this response following moderate-dose cocaine priming injections in the HiS rats. Histamine was equally effective in punishing cocaine self-administration in both phenotypes; however, LoS rats exhibited a delay in reaching baseline levels of self-administration following histamine punishment. By demonstrating that phenotypic variance in sweet preference can predict treatment sensitivity in substance-dependent individuals, these data can inform more effective, personalized treatment strategies.
  • Thumbnail Image
    Item
    Selective attention and Individual differences in infant learning: a comprehensive investigation of exogenous orienting among 7-month-old infants.
    (2010-09) Markant, Julie C.
    Young infants learn incredible amounts of information as they interact with their environment, often without any explicit instruction. Though researchers have identified mechanisms that support learning about regularities in the environment, it is unclear how these mechanisms contend with the massive amount of potentially relevant stimuli available in the world. Selective attention may constrain early learning, since information that is selectively attended may be preferentially processed by learning mechanisms. Previous studies have relied on social-cueing paradigms to examine learning of selectively attended items. However, attention can also be manipulated in a non-social manner using the spatial cueing paradigm, in which salient spatial cues initiate exogenous shifts of attention. Individuals are typically faster to respond to items appearing in the cued location; however, this facilitation is dependent on the timing between the cue and target presentations. Following relatively short cue-target delays, attention is biased towards targets in the cued location, whereas longer delays bias attention towards targets in the non-cued location, a process known as inhibition of return (IOR). This dissertation consists of two studies. Study 1 examined whether selective attention biases modulate 7-month-old infants’ learning of predictable information. Study 2 addressed individual differences in 7-month-old infants’ sensitivity to spatial cues. Specifically, Study 2A examined the consistency of cueing behavior across repeated testing, while Studies 2B and 2C explored behavioral and genetic factors that may influence variation in infants’ sensitivity to spatial cues. Results of Study 1 indicated that spatial cueing modulated selective attention, with enhanced learning of the item that was preferentially attended. Study 2A demonstrated stability in IOR behaviors when using qualitative (categorical) but not quantitative measures. Studies 2B and 2C found that variations in infants’ sensitivity to spatial cues were related to both individual differences in their reactivity to novel stimuli and genetic polymorphisms that affect the dopamine and acetylcholine neurotransmitter systems. These results highlight the complexity of interactions between early attention and learning processes, the wide array of factors that may impact infants’ responses during a basic attention task, and the range of neural systems that are likely involved in early selective attention.
  • Thumbnail Image
    Item
    Tracing causes and consequences of human intelligence through genetic and cognitive data
    (2020-12) Willoughby, Emily
    The work included in this dissertation represents empirical inquiries into three areas of cause and consequence for individual differences in human intelligence: How molecular genetic data can be used to draw inference about environmental mechanisms, how intelligence relates to information processing in the brain, and whether intelligence is meaningfully malleable by parental influence into adulthood. Study 1 uses polygenic scores derived from a large GWAS of educational attainment to demonstrate “genetic nurture”, through which the unique genetics of parents can give rise to passive gene-environment correlation that affects their offspring’s years of education. Study 2 explores the observation that faster reaction time (RT) on elementary cognitive tasks (ECTs) is associated with higher g. By partitioning stimuli into perceptual and decisional stages of information flow, we show through both additive-factors logic and diffusion modeling that g is expressed uniquely in the decisional, but not perceptual, stage of processing. Finally, Study 3 examines the sources of variance in IQ in a fully adult sample of adoptive and biological families to provide new evidence about the extent of IQ’s malleability. We find that the environment fostered by the parents explains less than 3% of the variance in their offspring’s IQ scores in adulthood. In sum, the converging operations afforded by twin and adoption studies, GWAS, and ECTs can address crucial questions of causal inference in human intelligence.