Social and Behavioral Sciences Commons^™

In Search Of Psychiatric Kinds: Natural Kinds And Natural Classification In Psychiatry, Nicholas Slothouber

Electronic Thesis and Dissertation Repository

In recent years both philosophers and scientists have asked whether or not our current kinds of mental disorder—e.g., schizophrenia, depression, bipolar disorder—are natural kinds; and, moreover, whether or not the search for natural kinds of mental disorder is a realistic desideratum for psychiatry. In this dissertation I clarify the sense in which a kind can be said to be “natural” or “real” and argue that, despite a few notable exceptions, kinds of mental disorder cannot be considered natural kinds. Furthermore, I contend that psychopathological phenomena do not cluster together into kinds in the way that paradigmatic natural kinds (e.g., chemical …

How Do Humans Process Magnitudes? An Examination Of The Neural And Cognitive Underpinnings Of Symbols, Quantities, And Size In Adults And Children, Helen Moriah Sokolowski

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A striking way that humans differ from other species is our unique ability to represent and manipulate symbols. This ability to process numerical magnitudes symbolically (e.g., ‘three’, ‘3’) is widely thought to be supported by an ancient system that evolved to process nonsymbolic numerical magnitudes (i.e., quantities). In this thesis, I present four empirical studies to uncover whether symbolic representations are indeed supported by the system that evolved to process quantities, or if symbolic representations are sub-served by a similar but ultimately distinct system.

In experiments 1 and 2, I investigate how the adult brain processes symbols and quantities using …

How Does The Brain Represent Digits? Investigating The Neural Correlates Of Symbolic Number Representation Using Fmri-Adaptation, Celia Goffin

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How does the brain represent numerical symbols (e.g., Arabic digits)? Activity in left parietal regions correlates with symbolic number processing. Research with functional resonance imaging adaptation (fMRI-A) indicates that the intraparietal sulcus (IPS) exhibits a rebound (increase in activation) effect when a repeatedly presented number is followed by a new number. Importantly, this rebound effect is modulated by numerical ratio as well as the difference between presented numbers (distance). This ratio-dependent rebound effect could reflect a link between symbolic numerical representation and an approximate number system (ANS). In this doctoral dissertation, fMRI-A is used to investigate mechanisms underlying symbolic number …

Cognitive, Neural, And Educational Contributions To Mathematics Performance: A Closer Look At The Roles Of Numerical And Spatial Skills, Zachary C.K. Hawes

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The principal aims of this thesis were to (1) provide new insights into the cognitive and neural associations between spatial and mathematical abilities, and (2) translate and apply findings from the field of numerical cognition to the teaching and learning of early mathematics.

Study 1 investigated the structure and interrelations amongst cognitive constructs related to numerical, spatial, and executive function (EF) skills and mathematics achievement in 4- to 11-year old children (N=316). Results revealed evidence of highly related, yet separable, cognitive constructs. Together, numerical, spatial, and EF skills explained 84% of the variance in mathematics achievement (controlling for chronological age). …

The Relations Between Newcomer Integration Processes And Youth Athletes’ Perceptions Of The Group Environment In Competitive Ice Hockey, Jeffrey J. Chamberlain

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Abstract

The ways in which new members are integrated into a particular group environment—also known as organizational socialization processes—have been shown to be a powerful predictor of newcomer adjustment in the workplace. Yet, there is a scarcity of research on how sport teams manage the integration of new team members, and the consequences of different tactics. The current research uses the recently developed Sport Team Socialization Tactics Questionnaire (STSTQ) to evaluate how socialization processes are systematically related to youth athletes’ perceptions of their group environment. Across two time points, 202 competitive adolescent ice hockey players (M_age = 14.47, …

Using Meditation To Improve Measures Of Attention In Older Adults, Sabrina Ford

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Age-related cognitive decline greatly impacts quality of life for older adults. Previous research has indicated that meditation may act as a neuroprotective factor to prevent age-related cognitive decline. This thesis sought to replicate previous findings and investigate if a four-week meditation intervention would improve sustained attention. Participants 60 years and older (n=27, 17 female) were recruited and assigned to a focused-attention (FA) meditation or relaxation group which met for four weeks, three times a week. Resting-state EEG was used to collect individual alpha peak frequency (iAPF) and frontal alpha asymmetry (FAA). The Sustained Attention to Response Task (SART) was also …

Pattern Separation In The Ventral Visual Stream, Kayla Ferko

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Pattern separation is a neural computation thought to underlie our ability to form distinct memories of similar events. It involves transforming overlapping inputs into less overlapping outputs. In the ventral visual stream (VVS) there is considerable evidence for hierarchical transformation from feature-based visual representations to conjunctive whole-object representations, with the latter allowing for distinct coding even when objects have significant feature overlap. In the current study, we asked whether this transformation can be understood as pattern separation, and whether pattern separation can be observed even outside the context of classic recognition-memory tasks. To investigate pattern separation in the VVS, we …

Improving Stimulus Realism: The Effect Of Visual Dimension On Affective Responding, Shannon Compton

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For decades researchers have used 2D stimuli under the assumption that they accurately represent real objects. This assumption has been challenged by recent vision and neuroeconomics research which has found that 2D images can evoke different neural and behavioural responses than real objects. The current study continues this line of research in the field of affective cognitive neuroscience; a field where small effect sizes are common and rapid habituation to affective stimuli used in the lab often occurs. The present study uses realistic 2D and 3D emotional images to determine the impact of visual dimension on affective responding. Subjective ratings …

Neurodevelopmental Outcomes Of Infantile Hydrocephalus: An Fmri Case Study, Ikhlas Ahmed Hashi

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Ventricle dilatation caused by infantile hydrocephalus may result in extensive damage of the posterior cortex (parietal and occipital lobes). We hypothesize that pathological changes in the development of the posterior cortex can be linked to non-verbal learning disabilities in children with previous infantile hydrocephalus. This case study will investigate the neurodevelopmental outcomes of 3 treated hydrocephalus patients, when compared to a group of healthy control children (n = 12). Within the hydrocephalus group, patients displayed differences in non-verbal test performance as well as parietal brain activation during an fMRI number comparison task. We associated these differences with clinical variables such …

Resedent Study- Reducing Sedentary Behaviour May Slow Cognitive Decline In Older Adults With Mild Cognitive Impairment: A Pilot Study, Kirsten B. Dillon

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Physical activity (PA) has been shown to slow down dementia. Unfortunately, older adults spend most of their day in sedentary behaviours (SB). Breaking up prolonged bouts of sitting with intermittent bouts of light intensity PA may reduce glycemic variability in the brain; potentially mitigating cognitive decline. This study investigated how interrupting SB with 10 min bouts of light intensity PA 3x a day would affect mild to moderate cognitive impairment progression (primary outcome) in older adults residing in an assisted living facility. Participants (n=25) were assigned in clusters into a two arm 10-week single site pilot randomized controlled trial. Secondary …

Investigating How Neural Entrainment Relates To Beat Perception By Disentangling The Stimulus-Driven Response, Aaron Wc Gibbings

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Beat perception – the ability to perceive a steady pulse in music – is nearly ubiquitous in humans, but the neural mechanisms underlying this ability are unknown. A growing number of electroencephalography (EEG) studies suggest that beat perception is related to neural entrainment, a phenomenon in which cyclic changes in the excitability of populations of neurons synchronize with a rhythmic stimulus. However, the relationship between acoustically-driven and entrainment-driven neural activity is unclear. This thesis presents EEG research that extends our understanding neural entrainment is related to beat perception by characterizing, equating, and finally removing the stimulus-driven response in the neural …

The Effects Of Acute Aerobic Exercise And Caffeine On Working Memory And Caffeine Withdrawal, Anisa Morava

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Caffeine is one of the most widely used psychoactive substances worldwide. Although caffeine elicits cognitive benefits, there are concerns regarding caffeine’s effects on certain health domains. Acute, aerobic exercise has been shown to improve cognition. The effects of aerobic exercise in comparison to caffeine on working memory (WM) in non-caffeine and caffeine consumers remains unknown. Furthermore, the effects of aerobic exercise in reducing caffeine withdrawal symptoms has yet to be examined. In Phase I, twenty-nine non-caffeine and thirty caffeine consumers completed a WM assessment, followed by aerobic exercise and caffeine administration (counterbalanced). In Phase II, twenty-five caffeine consumers underwent a …

The Origins And Development Of Visual Categorization, Laura Cabral

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Forming categories is a core part of human cognition, allowing us to make quickly make inferences about our environment. This thesis investigated some of the major theoretical interpretations surrounding the neural basis of visual category development. In adults, there are category-selective regions (e.g. in ventral temporal cortex) and networks (which include regions outside traditional visual regions—e.g. the amygdala) that support visual categorization. While there has been extensive behavioural work investigating visual categorization in infants, the neural sequence of development remains poorly understood. Based on behavioral experiments, one view holds that infants are initially using subcortical structures to recognize faces. Indeed, …

Cultivating Knowledge: Agrarian Science And Ecological Engagements In Southern Ontario Agriculture, Kelly Linton

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Agriculture and climate change are interconnected processes, with agriculture implicated in rising green house gas emissions, deforestation, soil and water pollution, and reductions in biodiversity. Conversely, changes within ecology (including a warming climate), alter growing conditions for farmers. Farmers face changes in both temperature and precipitation, as well as an increase in adverse weather events that significantly threaten productivity and livelihoods.

Based on 40 unstructured interviews as well as informal conversations conducted among farmers in southern Ontario, Canada between the spring of 2014 and the winter of 2017, this dissertation seeks to contribute to a growing body of work that …

True North Strong Canada 150: Canadian Identity And Its Contribution To Doping Free Sport, Helena A. Hlas

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This thesis, a reflective piece inspired by “Canada 150” events, explores the psychosocial and sociocultural factors surrounding the ongoing evolution of the clean sport movement in Canada. A literature review recounts the critical events in the history of doping, viz. the Ben Johnson scandal, which resulted in a call to overhaul sport culture and realign it with fair play values. Theories in sports philosophy and psychology provide a further understanding of the meaning of sport, and psychosocial factors that are inextricably linked to doping behavior, respectively. The autoethnographic method provides insight into current Canadian values to compare with those in …

Cardiodynamic Associations With Resilience In Undergraduate Students And The Effect Of A Mentorship Intervention, Rachel J. Knetsch

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The National College Health Assessment (NCHA) indicates that a majority of Canadian university students report feeling overwhelmed, stressed, and anxious during their undergraduate studies. Resilience refers to positive adaptation, or the ability to maintain or regain mental health, despite experiencing adversity (Herrman et al., 2011). While autonomic indices have been used to describe chronic physiological stress, the role of heart rate variability (HRV) as an index of resilience remains unclear. This research tested the hypotheses that (1) there is a relationship between HRV and resilience scoresand (2) a mentorship intervention will improve HRV and resilience outcomes. Fifty-seven first year students …

Characterizing The Cognitive And Emotional Effects Of Delta-9-Tetrahydrocannabinol In Distinct Hippocampal Sub-Regions, Dinat Khan

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The objective of this study is to determine the potential differential effects of THC in the DH or VH sub-regions, as well as the upstream effects on PFC neuronal activity and oscillations. Rodents used for electrophysiology were infused with THC or vehicle in the DH or VH regions, combined with PFC recordings. Additionally, a battery of behavioural paradigms was performed. Deficits in short-term memory when THC was infused into both regions was observed, however working memory was impaired with VH infusions only. This could be due to THC-induced dysregulation in the PFC, as beta oscillations were significantly decreased selectively in …

Pilot Study: Heart Rate Variability Analysis And Mental Health Outcomes In University Female Hockey Players, Kaitlyn Jacobs

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Exercise improves anxiety and depression, both of which are associated with impaired autonomic regulation of heart rate (HR). In turn, HR variability (HRV) is a reliable physiological indicator of external stressors. The following research tested the hypothesis that HRV is indicative of chronic resilience towards mental stress in female varsity hockey players. Seventeen varsity hockey players (HOCK, age 21 ± 1.5) and fifteen healthy controls (CTRL, age 21 ± 2.2) at Western University participated three times throughout a 7-month season. Participants completed questionnaires (brief resilience scale, BRS; generalized anxiety scale, GAD-7; mental health inventory, MHI; visual analog scale, VAS; short …

Girls’ Internalizing Symptoms And White Matter Tracts In Cortico-Limbic Circuitry, Ola Mohamed Ali

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Dysfunction in cortico-limbic circuitry is implicated in internalizing disorders, but less is known about whether structural abnormalities precede disorder, thus potentially marking risk. I therefore examined associations between white matter tract integrity in cortico-limbic circuitry at age 7, obtained using Diffusion Tensor Imaging, and concurrent and longitudinal patterns of internalizing symptoms, over a 5-year period, in 42 typically developing girls. Using Automated Fiber Quantification, diffusion properties were examined at multiple points along tract length (cf., an average diffusion measure of the entire tract). Concurrent internalizing symptoms were associated with reduced fractional anisotropy in segments of the cingulum bundle and uncinate …

Participatory Action Research Examining The Role Of Physical Activity In Mentoring For Resilience, Francesca Gable

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This study examined the use of physical activity-based mentorship programs to positively influence student mental health and resilience in post-secondary institutions. The process of relationship building was observed through regularly implemented physical activity interactions over time. The purpose was to determine the ability of a physical activity-based mentorship relationship to positively influence student resilience. A participatory action research methodology was used to engage with a population of ninety undergraduate Kinesiology students (30 mentors:60 protégés) over an eight-month period. Sixty interviews and thirteen focus groups were conducted, and fifteen-hundred pages of journal reflections were consulted to further understand the relationship building …

Characterizing Mekk1: Candidate Behavioural Isolation Gene, Caryn Dooner

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Behavioural isolation can occur due to divergence in aspects of courtship and mating, and can contribute to reproductive isolation. The purpose of this study is to determine how a gene, Mekk1, contributes to female rejection behaviour between D. melanogaster and D. simulans. Unique polymorphisms were identified within D. simulans Mekk1 that could contribute to behaviour, most of which are non-coding. Both transcripts of Mekk1 appear to be expressed at similar levels in D. simulans and D. melanogaster. These data also indicate that Mekk1 may be expressed in a specific region of the brain called the mushroom body, …

A Simulated Walk In Nature: Testing Predictions From The Attention Restoration Theory, Corey Crossan

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Attention Restoration Theory (ART) predicts that top-down processing during everyday activities can cause attentional fatigue and that bottom-up processing that occurs when people experience nature will be restorative (Kaplan, 1995). The present study examined this prediction by exposing participants to three different conditions using a repeated measures design: a control condition during which participants walked on a typical treadmill, a nature/restorative condition during which participants walked on the same treadmill, experiencing a simulated nature walk, and a perturbation condition that included the same simulated nature scene but also required top-down processing during the walk. The findings supported ART predictions. As …

The Neural Mechanisms Underlying The Perception And Production Of Learned Vocalizations In Songbirds, Shannon Katie Mischler

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Songbirds produce a wide array of vocalizations, including song, and learned and innate calls. Songs and calls can be functionally defined. Songs are typically used to attract potential mates and defend one’s territory, whereas calls are used for everything else, such as advertising the presence of a predator, or location of a food source, and maintaining contact with members of one’s flock. The purpose of this thesis was to better understand the neural mechanisms underlying call production and perception in two songbird species; the black-capped chickadee (Poecile atricapillus) and the zebra finch (Taeniopygia guttata). My objectives …

A Diffusion Tensor Imaging Study Of Motor Fibre Path Integrity And Overt Responsiveness In Disorders Of Consciousness, Clara A. Stafford

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This study investigated the relationship between motor thalamo-cortico-cerebellar fibre path integrity and overt responsiveness in patients with disorders of consciousness (DOC). Additionally, we investigated the potential of imaging these motor tracts at ultra-high fields. Study I and II aimed to map the white matter connections of motor execution fibres in DOC patients. Our results showed significant reductions in motor fibre path integrity across DOC diagnostic categories. Study III and IV aimed to develop a 7T MRI Diffusion Tensor Imaging (DTI) sequence. We optimized this sequence to image motor fibre paths in DOC patients. We concluded that, in healthy controls, probabilistic …

An Investigation Of Propranolol As An Agent For The Experimental Manipulation Of Interoception., Jane Evguenia Kouptsova

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Interoception has recently come under research focus as a potential influence on emotional and epistemic feelings. However, existing means to manipulate it experimentally have conceptual or logistical drawbacks. We investigated whether 20 mg of propranolol is a viable agent for experimentally manipulating interoception. Thirteen participants completed a double-blind, placebo-controlled crossover study, performing two heartbeat perception tasks, control tasks and measures of anxiety and alertness. All measures were obtained at the beginning and end of both sessions. Propranolol significantly decreased heart rate and systolic blood pressure. Heartbeat detection performance numerically decreased under propranolol, although this effect failed to reach statistical significance. …

The Influence Of Estrogen On Sex Differences In Chemotherapy-Induced Nausea And Vomiting (Cinv), Danna L. Zevy

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Chemotherapy-induced nausea and vomiting (CINV) is one of the most distressing events that affects the quality of life of cancer patients. Evidence suggests that females are more susceptible to CINV than males, but the mechanism remains unknown. The current thesis examined whether higher levels of circulating estrogens in females contributes to this sex difference. CINV was analyzed in a pediatric oncology population, where it was revealed female patients demonstrate increased delayed CINV relative to male patients, in the post-pubertal age group. CINV was also studied by examining the influence of the estrous cycle on anticipatory nausea (AN) in rats. This …

Promoting Benefits Of Physical Activity Through Persuasive Communication, Priynka Patil

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Inactivity early in life can lead to inactively later in life, which can result in negative outcomes. The primary purpose was to determine if gain- or loss-framed messages about physical activity would change the attitudes, intentions, and behaviours of students in the contemplation or preparation stage of the Transtheoretical model. The secondary purpose was to determine if framing the message in terms of the physical health benefits, appearance/social benefits, or mental health benefits (benefit condition) would change attitude, intention and behaviour. Undergraduate female students (N=60) between the ages of 18 and 36 were recruited from the university. The results found …

The Neural And Cognitive Basis Of Cumulative Lifetime Familiarity Assessment, Devin Duke

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Perirhinal cortex (PrC) has been implicated as a brain region in the medial temporal lobes (MTL) that critically contributes to familiarity-based recognition memory, a process that allows for recognition to occur independently of contextual recollection. Informed by neurophysiological research in non-human primates, fMRI, as well as behavioural work in humans, the current thesis research tests the novel hypothesis that PrC cortex functioning also underlies the ability to assess cumulative lifetime familiarity with object concepts that are characterized by a lifetime of experiences. In Chapter 2, a patient (NB) with a left anterior temporal lobe (ATL) lesion that included PrC as …

A Systems Approach To Modelling The Effects Of Climate Change On Agroforestry: A Case Study In Western Tanzania, Elaine M. Samuel

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Climate change is anticipated to have significant effects on agricultural production in sub-Saharan Africa as the magnitude of weather events increase in severity. Smallholder farmers in western Tanzania are potentially vulnerable to climate change impact as crops rely on precipitation as the only source of water. It is prudent to evaluate different modes of agricultural adaptations, such as agroforestry, that these farmers can easily adopt to improve their resiliency to the effects of climate change. System dynamics modelling is a cost-effective tool to simulate the long-term behaviour of agroforestry systems under future climate conditions. Water, Nutrient, and Light Capture in …

Exploring And Training Spatial Reasoning Via Eye Movements: Implications On Performance, Victoria A. Roach

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This dissertation sought to determine if eye movements could serve as an indicator of success in spatial reasoning, and if eye movements associated with successful completion could be applied to strategically improve spatial reasoning.

Using the line images of Shepard and Metzler, an electronic test of mental rotations ability (EMRT) was designed. Two versions of the test were created, allowing for both a timed (6 seconds per question) and untimed testing environment. Four experiments were designed and completed to relate mental rotation ability (MRA) scores from the EMRT, to patterns in chrononumeric and visual salience data. In each experiment, participants …