Individual Differences in Executive (Dys)function in Relation to Sleep Duration and Psychopathology

This dissertation presents four studies that examined how executive functions (EFs) relate to problematic behaviors, such as psychopathology and atypical sleep, as well as how EFs are characterized in healthy individuals. The first study examined whether genetic risk for five different forms of psychopathology predicted EFs at the latent variable level in a population sample. The second study characterized the neural activation patterns in health individuals in response to 3 different types of EF tasks. This study (a) assessed the overlapping activation elicited across the different EF task types, and (b) used neural activation to predict high or low EF ability. The third study examined whether individual differences in sleep duration influenced either depression or EFs (a) within a single time of assessment, (b) across time, and (c) how sleep duration, depression, and EFs influence each other in the same model. Study 4 decomposed the relationships of sleep duration with depression and then EF into their genetic and environmental factors in order to better understand the underlying architecture for these relationships.In the first study, publically available datasets from the Psychiatric Genomics Consortia were used to generate polygenic risk scores for 5 different psychiatric disorders: Autism, Attention Deficit Hyperactivity Disorder (ADHD), Bipolar Disorder, Major Depressive Disorder (MDD), and Schizophrenia. I then used a deeply phenotyped (and genotyped) subset of 354 twins in the Colorado Longitudinal Twin Study (LTS) from the University of Colorado Boulder to test whether or not genetic risk in these individuals predicted EF abilities. I also examined whether the appropriate risk scores were associated with ADHD and MDD symptoms or lifetime diagnoses to the same relative extent as the EF scores. Results indicated polygenic risk for psychopathology did not significantly predict EFs after controlling for multiple testing. Results also suggested that effect sizes for EFs were comparable to those for ADHD and MDD symptoms and lifetime diagnoses. The second study was a pilot study that included 30 subjects from the Colorado Twin Study from the University of Colorado Boulder at approximately age 28. These subjects were chosen because they were either high or low in Common EF ability as measured in a previous wave of data collection 7 years prior, until we had 15 of each. Each subject completed 3 EF tasks in a functional magnetic resonance imaging scanner. Results indicated that common brain activation in response to these tasks both overlapped with a frontoparietal network typically associated with cognitive tasks, and extended beyond this network. The common areas associated with individual differences in EF ability fell outside of the frontoparietal network. The third and fourth studies utilized data from the same group of 857 twins from the LTS sample. These studies examined sleep, depression, and EF when available at approximately ages 12, 17, 21, and 23. Study three looked at the phenotypic relationships between these variables and found linear and nonlinear relationships between sleep duration and EFs and depression across age. When put together in the same model, depression seems to suppress the relationship between EF and sleep duration in adolescence. Study four results showed that sleep duration is moderately heritable, and that the phenotypic relationships between these variables is typically attributable to non-shared environmental influences

Grundlegende Beziehungen für ein thermo-elastisch-plastisches Kriechmaterialmodell mit gemischter Verfestigung

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Lösung thermoelastisch-plastischer Aufgaben mit der FEM

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Implementation of CT and IHT Processors for Invariant Object Recognition System

This paper presents PDL or ASIC implementation of key modules of invariant object recognition system based on the combination of the Incremental Hough transform (IHT), correlation and rapid transform (RT). The invariant object recognition system was represented partially in C++ language for general-purpose processor on personal computer and partially described in VHDL code for implementation in PLD or ASIC

Individual Differences in Executive (Dys)function in Relation to Sleep Duration and Psychopathology

This dissertation presents four studies that examined how executive functions (EFs) relate to problematic behaviors, such as psychopathology and atypical sleep, as well as how EFs are characterized in healthy individuals. The first study examined whether genetic risk for five different forms of psychopathology predicted EFs at the latent variable level in a population sample. The second study characterized the neural activation patterns in health individuals in response to 3 different types of EF tasks. This study (a) assessed the overlapping activation elicited across the different EF task types, and (b) used neural activation to predict high or low EF ability. The third study examined whether individual differences in sleep duration influenced either depression or EFs (a) within a single time of assessment, (b) across time, and (c) how sleep duration, depression, and EFs influence each other in the same model. Study 4 decomposed the relationships of sleep duration with depression and then EF into their genetic and environmental factors in order to better understand the underlying architecture for these relationships. In the first study, publically available datasets from the Psychiatric Genomics Consortia were used to generate polygenic risk scores for 5 different psychiatric disorders: Autism, Attention Deficit Hyperactivity Disorder (ADHD), Bipolar Disorder, Major Depressive Disorder (MDD), and Schizophrenia. I then used a deeply phenotyped (and genotyped) subset of 354 twins in the Colorado Longitudinal Twin Study (LTS) from the University of Colorado Boulder to test whether or not genetic risk in these individuals predicted EF abilities. I also examined whether the appropriate risk scores were associated with ADHD and MDD symptoms or lifetime diagnoses to the same relative extent as the EF scores. Results indicated polygenic risk for psychopathology did not significantly predict EFs after controlling for multiple testing. Results also suggested that effect sizes for EFs were comparable to those for ADHD and MDD symptoms and lifetime diagnoses. The second study was a pilot study that included 30 subjects from the Colorado Twin Study from the University of Colorado Boulder at approximately age 28. These subjects were chosen because they were either high or low in Common EF ability as measured in a previous wave of data collection 7 years prior, until we had 15 of each. Each subject completed 3 EF tasks in a functional magnetic resonance imaging scanner. Results indicated that common brain activation in response to these tasks both overlapped with a frontoparietal network typically associated with cognitive tasks, and extended beyond this network. The common areas associated with individual differences in EF ability fell outside of the frontoparietal network. The third and fourth studies utilized data from the same group of 857 twins from the LTS sample. These studies examined sleep, depression, and EF when available at approximately ages 12, 17, 21, and 23. Study three looked at the phenotypic relationships between these variables and found linear and nonlinear relationships between sleep duration and EFs and depression across age. When put together in the same model, depression seems to suppress the relationship between EF and sleep duration in adolescence. Study four results showed that sleep duration is moderately heritable, and that the phenotypic relationships between these variables is typically attributable to non-shared environmental influences

Homeostatic regulation of sleep in the white-crowned sparrow (Zonotrichia leucophrys gambelii)

<p>Abstract</p> <p>Background</p> <p>Sleep is regulated by both a circadian and a homeostatic process. The homeostatic process reflects the duration of prior wakefulness: the longer one stays awake, the longer and/or more intense is subsequent sleep. In mammals, the best marker of the homeostatic sleep drive is slow wave activity (SWA), the electroencephalographic (EEG) power spectrum in the 0.5–4 Hz frequency range during non-rapid eye movement (NREM) sleep. In mammals, NREM sleep SWA is high at sleep onset, when sleep pressure is high, and decreases progressively to reach low levels in late sleep. Moreover, SWA increases further with sleep deprivation, when sleep also becomes less fragmented (the duration of sleep episodes increases, and the number of brief awakenings decreases). Although avian and mammalian sleep share several features, the evidence of a clear homeostatic response to sleep loss has been conflicting in the few avian species studied so far. The aim of the current study was therefore to ascertain whether established markers of sleep homeostasis in mammals are also present in the white-crowned sparrow (<it>Zonotrichia leucophrys gambelii</it>), a migratory songbird of the order Passeriformes. To accomplish this goal, we investigated amount of sleep, sleep time course, and measures of sleep intensity in 6 birds during baseline sleep and during recovery sleep following 6 hours of sleep deprivation.</p> <p>Results</p> <p>Continuous (24 hours) EEG and video recordings were used to measure baseline sleep and recovery sleep following short-term sleep deprivation. Sleep stages were scored visually based on 4-sec epochs. EEG power spectra (0.5–25 Hz) were calculated on consecutive 4-sec epochs. Four vigilance states were reliably distinguished based on behavior, visual inspection of the EEG, and spectral EEG analysis: Wakefulness (W), Drowsiness (D), slow wave sleep (SWS) and rapid-eye movement (REM) sleep. During baseline, SWA during D, SWS, and NREM sleep (defined as D and SWS combined) was highest at the beginning of the major sleep period and declined thereafter. Moreover, peak SWA in both SWS and NREM sleep increased significantly immediately following sleep deprivation relative to baseline.</p> <p>Conclusion</p> <p>As in mammals, sleep deprivation in the white-crowned sparrow increases the intensity of sleep as measured by SWA.</p

Overnight changes in waking auditory evoked potential amplitude reflect altered sleep homeostasis in major depression

Objective: Sleep homeostasis is altered in major depressive disorder (MDD). Pre- to postsleep decline in waking auditory evoked potential (AEP) amplitude has been correlated with sleep slow wave activity (SWA), suggesting that overnight changes in waking AEP amplitude are homeostatically regulated in healthy individuals. This study investigated whether the overnight change in waking AEP amplitude and its relation to SWA is altered in MDD. Method: Using 256-channel high-density electroencephalography, all-night sleep polysomnography and single-tone waking AEPs pre- and postsleep were collected in 15 healthy controls (HC) and 15 non-medicated individuals with MDD. Results: N1 and P2 amplitudes of the waking AEP declined after sleep in the HC group, but not in MDD. The reduction in N1 amplitude also correlated with fronto-central SWA in the HC group, but a comparable relationship was not found in MDD, despite equivalent SWA between groups. No pre- to postsleep differences were found for N1 or P2 latencies in either group. These findings were not confounded by varying levels of alertness or differences in sleep variables between groups. Conclusion: MDD involves altered sleep homeostasis as measured by the overnight change in waking AEP amplitude. Future research is required to determine the clinical implications of these findings

Avoiding the Esophageal Branches of the Recurrent Laryngeal Nerve During Retractor Placement: Precluding Postoperative Dysphagia During Anterior Approaches to the Cervical Spine.

Study Design: Anatomical cadaver study. Objectives: Postoperative dysphagia is a significant complication following anterior approaches to the cervical spine and the etiology of this complication is poorly understood. Herein, we studied the esophageal branches of the recurrent laryngeal nerves to improve understanding of their anatomy and potential involvement in dysphagia. Methods: Ten fresh frozen cadaveric human specimens were dissected (20 sides). All specimens were adults with no evidence of prior surgery of the anterior neck. The recurrent laryngeal nerves were identified under a surgical microscope and observations and measurements of their esophageal branches made. Results: For each recurrent laryngeal nerve, 5-7 (mean 6.2) esophageal branches were identified. These branches ranged from 0.8 to 2.1 cm (mean 1.5 cm) in length and 0.5 to 2 mm (mean 1 mm) in diameter. They arose from the recurrent laryngeal nerves between vertebral levels T1 and C6. They all traveled to the anterior aspect of the esophagus. No statistical differences were seen between left and right sides or between sexes. Conclusion: The esophageal branches of the recurrent laryngeal nerve have been poorly described and could contribute to complications such as swallowing dysfunction following anterior cervical discectomy and fusion procedures. Therefore, a better understanding of their anatomy is important for spine surgeons. Our study revealed that these branches are always present on both sides and the anterior surface of the esophagus should be avoided while retracting it in order to minimize the risk of postoperative dysphagia

Impact of Nocturia on Health-Related Quality of Life and Medical Outcomes Study Sleep Score in Men

Purpose To evaluate the impact of nocturia on health-related quality of life and sleep in men. Methods From January 2008 to December 2008, 284 patients with lower urinary tract symptoms were selected for this study. The participants completed a series of questionnaires on health-related quality of life (the overactive bladder questionnaire, or OAB-q), the Medical Outcomes Study (MOS) sleep scale, and the frequency volume chart. Results The patient population had a mean age of 60.0±13.4 years (range, 40 to 79 years). The mean duration of symptoms was 28.8±34.6 months. The mean number of voiding episodes per night was measured as follows: 88 patients (31.0%) reported no nocturia, 60 patients (21.1%) reported 2>voids/night ≥1, 56 patients (19.7%) reported 3>voids/night ≥2, and 80 patients (28.2%) reported ≥3 voids/night. The mean number of nocturia episodes increased with age (P=0.001), and the number of nocturia episodes was significantly associated with the OAB-q symptom score (P=0.001) and symptom bother (P=0.001). Among the categories of the MOS sleep scale, sleep index I (P=0.020), sleep disturbance (P=0.010), adequacy of sleep (P=0.005), and somnolence (P=0.041) were significantly associated with an increased number of nocturia episodes. Conclusions The number of nocturia episodes increased with age in men. Nocturia appeared to be associated with further negative effects on sleep quality, health-related quality of life, and symptom bother

The Natural History of Insomnia: Acute Insomnia and First-onset Depression

Study Objectives: While many studies have examined the association between insomnia and depression, no studies have evaluated these associations 1) within a narrow time frame, 2) with specific reference to acute & chronic insomnia, and 3) using polysomnography. In the present study, the association between insomnia and first-onset depression was evaluated taking into account these considerations. Design: A mixed-model inception design. Setting: Academic research laboratory. Participants: Fifty-four individuals (acute insomnia (n=33), normal sleepers (n=21)) with no reported history of a sleep disorder, chronic medical condition, or psychiatric illness. Interventions: N/A Measurements and Results: Participants were assessed at baseline (two nights of polysomnography and psychometric measures of stress and mood) and insomnia and depression status were reassessed at 3 months. Individuals with acute insomnia exhibited more stress, poorer mood, worse subjective sleep continuity, increased N2 sleep and decreased N3 sleep. Individuals that transitioned to chronic insomnia exhibited (at baseline) shorter REM Latencies and reduced N3 sleep. Individuals that exhibited this pattern, in the transition from acute to chronic insomnia, were also more likely to develop first-onset depression (9.26%) as compared to those who remitted from insomnia (1.85%) or were normal sleepers (1.85%). Conclusion: The transition from acute to chronic insomnia is presaged by baseline differences in sleep architecture that have, in the past, been ascribed to Major Depression, either as heritable traits or as acquired traits from prior episodes of depression. The present findings suggest that the “sleep architecture stigmata” of depression may actually develop over the course transitioning from acute to chronic insomnia