<p>About 30 % of all infertile couples suffer from infertility of an unexplained cause. Leukemia inhibitory factor (LIF) is a glycoprotein produced by the endometrium and is an important cytokine in the implantation process. LIF exerts its biological functions through heterodimerization of its two receptors: LIF receptor (LIFR) and gp130. Point mutations in the LIF gene have been associated with female infertility. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in the genes of LIFR and gp130 could cause reduced fertility in women. To this end, 115 samples from women diagnosed with unexplained infertility and 191 samples from fertile women were studied. Three SNPs in the gp130 gene and two SNPs in the LIFR gene were analyzed using real-time PCR. One significant difference and a tendency to difference were detected in the gp130 gene for women with unexplained infertility. There were no differences in the LIFR gene variations. In conclusion, polymorphisms in gp130, and thereby disturbances in the LIF pathway, could be one cause for infertility in women diagnosed with unexplained infertility.</p>

<p>Deficits in higher order cognitive processes such as inhibitory control and working memory (WM), grouped under the term of executive function (EF), have been shown to constitute one important component of the complex neuropsychology of Attention Deficit Hyperactivity Disorder (ADHD). The aim of the present thesis was to examine EF in relation to ADHD, with primary focus on structure (i.e., dimensions) and developmental change. Rooted in the developmental and dimensional perspectives of ADHD, which propose that the disorder represents the extreme of or quantitative delays in traits that are present throughout the general population, four studies (I-IV) based on non-clinical and clinical samples of children at different developmental levels were conducted.</p><p>Together, the results from Study I-IV suggest that inhibitory control and WM are important components of EF in typically developing children as well as in relation to ADHD symptoms. Of particular interest are the findings from Study II, III, and IV, showing that inhibitory control and WM seem to be of different importance depending on the child’s age. More specifically, the non-clinical and clinical studies suggest that inhibitory control and WM are important in predicting ADHD symptoms, with deficits in inhibitory control primarily being associated with ADHD symptoms for preschool and younger elementary school-aged children, whereas deficits in WM are associated with ADHD symptoms for older elementary school-aged children. </p><p>In conclusion, the results of the present thesis are consistent with Barkley’s (1997) developmental prediction concerning the relation between EF and ADHD, which suggests that impaired inhibitory control is an early developmental precursor to or a factor that “sets the stage” for deficits in more complex EFs such as WM. The home taking message from the present thesis is that age matters not only in the behavioral, but also in the neuropsychological manifestation of ADHD. To our knowledge, these findings are among the first to show that age is an important factor that should be taken into account in future ADHD research, theory, and treatment.</p>

Deficits in higher order cognitive processes such as inhibitory control and working memory (WM), grouped under the term of executive function (EF), have been shown to constitute one important component of the complex neuropsychology of Attention Deficit Hyperactivity Disorder (ADHD). The aim of the present thesis was to examine EF in relation to ADHD, with primary focus on structure (i.e., dimensions) and developmental change. Rooted in the developmental and dimensional perspectives of ADHD, which propose that the disorder represents the extreme of or quantitative delays in traits that are present throughout the general population, four studies (I-IV) based on non-clinical and clinical samples of children at different developmental levels were conducted. Together, the results from Study I-IV suggest that inhibitory control and WM are important components of EF in typically developing children as well as in relation to ADHD symptoms. Of particular interest are the findings from Study II, III, and IV, showing that inhibitory control and WM seem to be of different importance depending on the child’s age. More specifically, the non-clinical and clinical studies suggest that inhibitory control and WM are important in predicting ADHD symptoms, with deficits in inhibitory control primarily being associated with ADHD symptoms for preschool and younger elementary school-aged children, whereas deficits in WM are associated with ADHD symptoms for older elementary school-aged children. In conclusion, the results of the present thesis are consistent with Barkley’s (1997) developmental prediction concerning the relation between EF and ADHD, which suggests that impaired inhibitory control is an early developmental precursor to or a factor that “sets the stage” for deficits in more complex EFs such as WM. The home taking message from the present thesis is that age matters not only in the behavioral, but also in the neuropsychological manifestation of ADHD. To our knowledge, these findings are among the first to show that age is an important factor that should be taken into account in future ADHD research, theory, and treatment.

About 30 % of all infertile couples suffer from infertility of an unexplained cause. Leukemia inhibitory factor (LIF) is a glycoprotein produced by the endometrium and is an important cytokine in the implantation process. LIF exerts its biological functions through heterodimerization of its two receptors: LIF receptor (LIFR) and gp130. Point mutations in the LIF gene have been associated with female infertility. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in the genes of LIFR and gp130 could cause reduced fertility in women. To this end, 115 samples from women diagnosed with unexplained infertility and 191 samples from fertile women were studied. Three SNPs in the gp130 gene and two SNPs in the LIFR gene were analyzed using real-time PCR. One significant difference and a tendency to difference were detected in the gp130 gene for women with unexplained infertility. There were no differences in the LIFR gene variations. In conclusion, polymorphisms in gp130, and thereby disturbances in the LIF pathway, could be one cause for infertility in women diagnosed with unexplained infertility.

The current study investigates whether younger adults process distraction semantically and how age influences the level of distraction processing. In a first experiment, younger adults’ processing of distraction was examined by comparing implicit and explicit memory for that distraction. Then, in a second experiment, younger and older adults’ semantic processing of distractors was directly tested by examining memory for distractors on a conceptually based category-generation task. Younger adults showed equivalent implicit and explicit distractor memory in the first experiment and no conceptual priming for distractors on the category-generation task of the second experiment. Older adults, on the other hand, showed reliable conceptual priming for distractors, and the effect was significantly correlated with age in that group. The results collectively suggest that older, but not younger, adults engage in elaborate processing of irrelevant information, and that this effect is possibly tied to inhibitory control abilities that tend to decrease with age.

Brain development and function depend on intrinsic and extrinsic factors. In particular, the proper functioning of sensory systems can be altered according to the quality of extrinsic sensory information received during life. In this context, questions concerning neuroplasticity take on special relevance when considering that sensory experience has a big impact on the degree of plasticity of the brain. In this thesis, we have sought to understand how visual deprivation affects the development and maintenance of visual centers in the brain and the role of visual deprivation on plasticity throughout life. We have addressed this question by studying the retinocollicular projection, which is the neuronal pathway that connects the retina with a visual input processing center, the superior colliculus (SC). Unexpectedly, we found that in Syrian hamsters (Mesocricetus auratus) the size of receptive fields (RFs) of neurons in the SC is plastic in adult animals if they have been deprived of a minimum of visual experience when juveniles. Specifically, dark-reared (DR) hamsters refine SC RFs as do their normally-reared counterparts, but they lose RF refinement if they remain in the dark after their RFs get refined. We found that a well defined period and duration of visual experience can stabilize RF size in adulthood. Furthermore, we sought to investigate the mechanisms by which RF size is increased in adult DR hamsters. By testing the strength of intracollicular inhibition using electrophysiological and molecular techniques, we have found that visually-deprived animals have weaker inhibitory circuitry in their SC than normal animals. The quantity of GABA receptors and GABA containing neurons is decreased in the SC of adult DR animals. We propose that these results explain at least in part the RF enlargement we find in visually-deprived animals. Knowledge from this study provides general insight into sensory system plasticity in adulthood and new information about visual system development that is relevant for treatments of diseases.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 134-172). Also available in electronic version. Access restricted to campus users.

Children use many cues to differentiate reality from fantasy, including context, testimony from others, and physical evidence in the world around them. However, due to individual differences, some children hold strong reality status biases that interfere with their ability to infer reality status from these cues correctly. This research identified two general cognitive skills, inhibitory control and a metacognitive understanding of certainty, which serve as mechanisms for overcoming biases to infer reality status. In general, children with a high interest in fantastical play and older children with poorer developed inhibitory control skills are more likely to display a reality status bias. Additionally, children with reality status biases are more likely to overcome them to infer reality status correctly when they have a better metacognitive understanding of certainty and better developed inhibitory control. This research informs both the fantasy/reality literature and the scientific reasoning literature in demonstrating how biases can affect children's judgments. / text

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

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