Visual snow syndrome is a persistent visual disturbance characterized by rapid flickering dots in the entire visual field. Hypothesized to arise from reduced inhibition of sensory cortex, visual snow has recently been linked to potentiation (enhancement) of the P100, an event-related potential (ERP) component associated with early visual processing. Here, we investigate whether this potentiation in visual snow is specific to visual responses, by comparing ERPs linked to early, bottom-up perceptual versus late, top-down cognitive processes. Specifically, we examined two components, the N170 and P300, associated respectively with rapid face categorization and attentional orienting towards targets. We predicted that if visual snow predominantly reflects diminished inhibition of perceptual areas, there should be stronger potentiation for the earlier perceptual N170 component. ERPs associated with the N170 (Face > House) and P300 (Target > Nontarget) were recorded in a 22 year-old male with a 2-year history of visual snow symptoms and a set of age- and gender-matched controls. Although N170 and P300 responses in all participants showed appropriate face- and target-selectivity, respectively, the visual snow patient demonstrated consistent potentiation relative to controls, particularly for the early N170 response. Bootstrapped estimates of mean amplitude computed within participants similarly revealed larger and more variable ERP amplitudes in the visual snow patient, especially for the N170 component. These results support an early perceptual locus of ERP potentiation in visual snow, further supporting the idea that this condition arises from diminished inhibition of sensory cortices.

Since its creation in 1998, the Implicit Association Test (IAT) has become a commonly used measure in social psychology and related fields of research. Studies of the cognitive processes involved in the IAT are necessary to establish the validity of this measure and to suggest further refinements to its use and interpretation. The current thesis used ERPs to study cognitive processes associated with the IAT. The first experiment found significant differences in P300 amplitude in the Congruent and Incongruent conditions, which were interpreted as a reflection of greater equivocation in the Incongruent condition. The second experiment tested the task-set switching account of the IAT in much greater detail by analyzing each trial type separately. In the Congruent condition, all trial types elicited the same amplitude P300. Local probability, and the consequent checking and updating of working memory, was thought to be responsible for differences between trials of the Incongruent condition that required or did not require a task switch. The final experiment examined the role of working memory in the IAT by introducing obtrusive and irrelevant auditory stimuli. The results of Experiment 3 indicated that the introduction of an obtrusive and irrelevant auditory increment deviant has little overall effect on the IAT, and a similar effect on switch and no-switch trials within the Incongruent condition. This could have been because both the Congruent and Incongruent conditions of the IAT make such extensive demands on central processing resources that few are available to allow for the switching of attention, or it is possible that the IAT does not require significant updating of working memory. The usefulness of ERPs in the study of the IAT effect is demonstrated by the current research. In particular, the finding that behavioural results were not always consistent with the ERP results demonstrates that electrophysiological measures can complement traditional behavioural measures.

Investigations into the cognitive effects of tobacco smoking have generally focused on nicotine and its effect on nicotinic acetylcholine receptors (nAChRs) in the brain. However, it is now known that chronic smokers exhibit robust inhibition of the monoamine oxidase (MAO) enzyme through the actions of non-nicotine components in tobacco smoke. Therefore, the primary aim of this thesis is to elucidate the effects of nicotine and MAO-inhibition on electroencephalographic (EEG) and event-related potential (ERP) measures of cognition. 24 healthy nonsmoking males were administered 75 mg of moclobemide, and chewed 6 mg nicotine gum, in order to simulate the effects of acute smoking. Four experimental conditions included placebo, nicotine, moclobemide, and a combination of nicotine and moclobemide. Early auditory ERPs were used as measures of cognition, such as the auditory P50 sensory gating paired-stimulus paradigm, the acoustic-change-elicited mismatch-negativity (MMN), the novel sound-elicited P3a, and the target sound-elicited P3b. Three minutes of eyes closed EEG were also recorded. Because these ERPs are often identified as biomarkers for schizophrenia, drug effects were also measured after individuals were stratified for low-baseline amplitude of each ERP measure, as a laboratory model of cognitive deficits in schizophrenia. Overall results showed a synergistic improvement in sensory gating via nicotine combined with moclobemide, accompanied by a reduction in theta band power. Nicotine in the absence of moclobemide increased P3b amplitude, accompanied by an increase in alpha2 band power. Moclobemide in the absence of nicotine increased P3a amplitude, accompanied by a decrease in beta2 power. Stratifying participants by placebo amplitude revealed both nicotine and moclobemide exhibited an inverted-U pattern of effect, i.e. showing greater amplitude increases in individuals with the lowest baseline amplitudes. Overall, this thesis demonstrates how these two components of tobacco smoke affect different facets of auditory processing in different ways, with synergistic effects in some paradigms but antagonizing effects in others. Therefore, chronic smokers and schizophrenia patients who seek transient cognitive improvement through smoking may actually experience cognitive detriments overall, possibly contributing to withdrawal symptoms and/or an exacerbation of already-present psychiatric symptoms.

Infants of mothers who have received narcotics on a continuous basis during pregnancy are born physically dependent. Drug withdrawal, one of many detrimental effects, is initially the most apparent. Neonatal abstinence syndrome (NAS) was originally described as a generalized disorder characterized by signs of central nervous system hyperirritability, gastrointestinal dysfunction, respiratory distress, and a host of vague autonomic manifestations. Recent studies have suggested that these same signs follow withdrawal from other addicting drugs as well. Feeding problems are the most common and important concomitants of neonatal withdrawal, because sucking function is uncoordinated, ineffectual and poorly sustained. Previous studies have shown a natural history of recovery of sucking dysfunction during recovery from NAS. A disposable and practical apparatus for monitoring nutritive sucking behaviour was developed, based on a prototype previously described in the literature. A weighted scoring system which encompasses the full spectrum of withdrawal signs was also designed. No significant difference in sucking rate was observed between normal and NAS babies on day 1 (p=0.8). There was a highly significant difference on day 2 (prO.0001), day 3 (p=0.0005), and day 4 (p=0.006). No significant difference in nutrient consumption was observed between normal and NAS babies on day 1 (p=0.9) and day 2 (p=0.8). A significant difference was observed on day 3 (p=0.006) and day 4 (p=0.03). A significant inverse correlation was demonstrated between both sucking rate and nutrient consumption with the classical clinical signs of withdrawal over the first two months of life (r=-0.57, -0.51, respectively). The periodic monitoring of sucking rate of the passively addicted infant provides an objective gauge of the seventy of withdrawal in NAS, eliminating the subjectivity of evaluating changes in clinical signs. Therefore, it is recommended that sucking rate measurements be instituted as a standard guide to the management of withdrawal in these infants. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Mängden vatten som når vattenkraftverken har betydelse för mängden el som kan produceras. Därav är det väsentligt att veta hur mycket vatten som finns i ett område och som kan bidra till elproduktionen. I områden där nederbörden till största del faller som snö kan det vara svårt att uppskatta hur mycket vatten som finns när snön sedan smälter. Genom att mäta snöns densitet kan man på ett säkrare sätt ta reda på hur mycket vatten som finns magasinerat i snö. Projektet berör Överumans avrinningsområde vilket är ett delavrinningsområde för Umeälven. Ett avrinningsområde är det geografiska område där allt vatten inom området bidrar till vattenflödet i en punkt längre nedströms. Genom att mäta snödensitet på olika djup har olika samband kunnat tas fram. Detta har gjorts genom att dels använda ett snörör för att få upp en snökärna men också genom att gräva snöschakt. Äldre mätvärden från Vattenregleringsföretagen har också erhållits. Snöschakt har gjorts i olika terrängtyper för att se om densiteten skiljer sig mellan kalfjäll, trädgränsen och i björkskogen medan snörör har använts på en yta av 50 x 50 m för att se hur representativt ett mätvärde är för ett större område. Syftet är att undersöka eventuella samband mellan terrängtyper och densitet som kan användas för att förenkla uppskattningen av snödensiteten i ett större område. Djupen för samtliga schakt var mellan 125-150 cm och vid mätningarna med snörör varierade snödjupet mellan ca 65-210 cm. Resultatet visar på en trend där snöns densitet ökar med djupet, för att närmare botten sedan bli mindre igen. Trenden var märkbar i samtliga terrängtyper men inte i alla djupprofiler. Resultatet för den rumsliga variationen visar på att det ser ut att finnas ett samband mellan snös densitet och snödjupet, samt att densiteten inom rutnätet varierar mycket. Mätvärdena visade på en relativt jämn korrelation fram till ett avstånd på ca 30 m, därefter minskade korrelationen.  Resultaten indikerar att mätvärdena kan variera mycket både rumsligt och i en djupprofil vilket medför att ett mätvärde inte representerar området i så stor utsträckning, utan kan variera mycket. Den ojämna fördelningen av snö vilken kunde observeras kan bero på en variation av träd i området samt att terrängen lutar. Lika så varierade densiteten mellan olika vegetationstyper, men vid indelning i olika terrängtyper verkar det finns en likhet mellan värden vilka är tagna inom samma terrängtyp. Trenden med att densiteten minskar närmare marken beror på en temperaturgradient som får snön att sublimeras och sedan deponeras på nytt vilket bildar så kallad ”depth hoar”, men att det inte var märkbart i alla djupprofiler visar också på lokala skillnader i marken.  För att utveckla projektet bör fler snöschakt göras inom samma terrängtyp för att lättare kunna jämföras med varandra och se vilka som avviker, samt studera den rumsliga variationen i fler terrängtyper. Sammanfattningsvis visar projektet på att det finns en rumslig variation av såväl snödjup som densitet i terrängen även på små skalor, samt att ett samband mellan snödjup och snöns densitet går att finna i olika grad.

Studies that expressly define the roles of related service providers in inclusive schools are limited. The purpose of this phenomenological study was to examine the lived experiences of related service providers, specifically occupational therapists, physical therapists, and speech and language pathologists, who practice in an inclusive education setting. An objective was to examine their attitudes and beliefs toward inclusion. This study used role theory as the theoretical framework. Tenets of role theory were used to explain how related service providers have come to understand their roles and responsibilities in the inclusion setting. Purposeful and snowball sampling yielded 10 participants who participated in semi-structured interviews. Data were analyzed using a multistep, phenomenological analysis method. The participants' descriptions of their involvement in inclusion revealed 7 themes: Expert/consultant, evaluator, direct service provider, mainstreaming, methods of collaboration, member of a multidisciplinary team, and documentation. Findings suggest a strong correlation between the perceived roles of the participants and the generic roles reported in the literature. Three themes emerged from their descriptions of their attitudes toward inclusion: general definition of inclusion, social/behavioral effects on inclusion, and barriers to inclusive education. The participants' views on the behavioral and social impact of inclusive education were mixed. Findings inform stakeholders about the day to day experiences of related service providers in an inclusion setting. This study represents a steppingstone toward increasing awareness of school-based professionals' contributions to the educational experience of special education students.

To date, research on mechanistic aspects of fluency disorders has focused heavily on motor contributions to stuttering. Only recently have researchers begun to explore psycholinguistic contributions to stuttering. Psycholinguistic planning for speech heavily involves the activation and processing of lexical information. We used a neuroscience approach to compare word activation in mental lexicon while completing a picture naming task in people who stutter (PWS) versus fluent individuals (PWNS). Twenty-eight individuals ranging in age from 19 - 52 years old participated in a picture-word priming task adopted from Jescheniak et al. (2002). Electroencephalogram (EEG) was recorded while participants saw black and white line drawings, followed immediately by an auditory probe word that was either Semantically-Related, Phonologically-Related, or Unrelated to the label of the preceding picture. EEG was also recorded to Filler (naming-only) trials. Averaged ERPs were generated for each condition. Two principal component analyses (PCA) were conducted in order to summarize patterns in the ERP data and test for differences in ERPs elicited by different conditions. One PCA compared Semantically-Related probe word trials, Semantically-Unrelated probe word trials, and Filler trials. The second PCA compared Phonologically-Related probe word trials, Phonologically-Unrelated probe word trials, and Filler trials. The primary goal of each analysis was to determine whether each probe word condition elicited ERP activity that was different from Filler (naming-only) trials. Relative to Filler trials, all four types of probe words elicited a series of ERP components, some related to sensory processing of the probe words, and some related to linguistic processing of the probe words including N400-type ERP activity. Crucially, N400 priming was observed for PWNS on Semantically-Related trials, but not for PWS. This result indicates that the activation of semantic word networks on the path to picture naming may operate differently in PWS versus PWNS. In contrast, no differences were found between groups for Phonological N400 priming. Discussion relates these effects to the larger body of existing literature on psycholinguistic ability in PWS. Discussion also focuses on how the activation of semantic word networks may differ in PWS versus PWNS, and how therapy for stuttering might address such differences.

Migraine is a debilitating neurological disorder, which affects over 10% of the general population. In addition to headache, migraine includes a host of associated symptoms, such as nausea and hypersensitivity to light, noise, and touch. While great strides have been made in migraine treatment in recent decades, the basic biological and pathophysiological mechanisms underlying migraine are still not well understood. Pain signals travel via a polysynaptic pathway from the periphery to the cortex, where conscious perception of pain occurs. This multi-neuron pathway produces a message that can be modified at any step of its transit. One peptide that may modify this pathway is calcitonin gene-related peptide (CGRP). CGRP is a potent vasodilator and neuromodulator, and mounting evidence suggests CGRP may play a causative role in migraine. CGRP levels are increased during migraine, but can be reduced upon successful treatment with drugs in the triptan class. Importantly, injection of CGRP into migraine patients can elicit a delayed, migraine-like headache. Finally, CGRP receptor antagonists are clinically effective in providing relief to migraine patients. In addition to CGRP, the CGRP gene (CALCA) expresses another peptide that may also be relevant to migraine. Procalcitonin (proCT) is a recognized biomarker for sepsis, but emerging evidence suggests it may have actions similar to CGRP in migraine. First, proCT has biological activity at the CGRP receptor. Second, proCT is reported to be increased during migraine. We hypothesized that regulation of CGRP and proCT may be altered in migraineurs, and that migraineurs may also be sensitized to the effects of these peptides. To study the role of these peptides in migraine pathways, a number of methods have been employed. Studies exploring regulation of gene expression were performed in cultured trigeminal ganglia, as well as primary cultures of trigeminal and cortical glia. These studies show that the Calca gene can be regulated by a number of stimuli, including hypoxia and reactive oxygen species. These insults have the ability to induce CALCA gene and peptide expression to varying degrees on different cell types. In addition to in vitro experiments on Calca gene regulation, the in vivo effects of CGRP on mouse behavior were also investigated. Animals were genetically sensitized to CGRP via overexpression of the rate-limiting CGRP receptor subunit. In these animals, injection of CGRP is sufficient to induce light aversion, which is used to model photophobia. Physiological and biochemical triggers of migraine were tested using this behavioral paradigm. While stress and mast cell degranulation are sufficient to induce light aversion, the role of CGRP in these events remains unclear, as both CGRP sensitized and control animals displayed a light aversion phenotype. Together, these studies show the dynamic regulation of the Calca gene in migraine pathways as well as highlight some of the challenges of modeling a complex disease in an animal model.

Error-related negativity (ERN) is an event-related potential elicited by the commission of errors. It appears as a negative deflection peaking between 50ms and 100ms after an erroneous response. Previous literature demonstrated that individuals who suffer from either anxiety or depression display a higher ERN amplitude compared to a control group. It has also been shown that people with ADHD display a lower ERN amplitude. Based on these findings, we investigated the relationships between these three disorders and their effects on the amplitude of the ERN. We recruited thirty-one students at East Tennessee State University and gathered data on their level of anxiety, depression, and ADHD through completion of three surveys: the Beck Anxiety Inventory, Beck Depression Inventory, and the ADHD self-report scale. Subsequently, participants were asked to perform a modified Flanker task while their EEG was collected using a 32-channel EEG cap. ERN amplitude for error responses was significantly higher than ERN amplitude for correct responses. In contrast with previous literature, no significant influence on the ERN was observed due to anxiety, depression, or ADHD. Additional research on the topic with larger sample size and different diagnostic procedures may be necessary to further investigate the phenomenon.

Technology has changed the relationship between work and life and allowed work to engage in our home lives. It is no longer the case that when the working day is over people switch off, rather it is when people go home and remain connected. In a culture where people are always connected via information and communication technology (ICT) the line between work and life has blurred. The present study investigated the relationship between ICT and occupational burnout with the mediating role of recovery experiences and their importance in the relationship. The study was conducted in Southern Sweden in Växjö.The study included 101 participants both male (N=53) and female (N=48) from public and private sectors where participants used ICT on a regular basis to perform job-related tasks. Data was collected using a self-reported web-based questionnaire. Results of the study revealed that there is no significant correlation between ICT and occupational burnout. However, it was found that there is a significant negative correlation between ICT and recovery experiences and a strong significant negative correlation between ICT and recovery experiences and occupational burnout. It was concluded that occupational burnout results from insufficient recovery from work-related stressors and not the stress itself. Keywords: work-related ICT, occupational burnout, recovery experiences, employee psychological well-being