Social and Behavioral Sciences Commons^™

Neural Responses To Magnetic Orientation Information In Songbirds, Madeleine Ir Brodbeck

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Effective navigation and orientation is essential for animals to survive. The study of migratory birds provides insights into these processes, particularly through mechanisms like the geomagnetic compass, which uses Earth's magnetic field for directional information. A brain region in songbirds relevant to this is cluster N, known for its potential role in processing geomagnetic information. Notably, cluster N appears exclusive to nocturnally migratory birds, being active solely at night, and lesion studies reveal that an intact cluster N is necessary for geomagnetic compass orientation. However, given the scarcity of empirical data concerning cluster N, substantial questions persist regarding its function. …

White Matter Connectome Associations With Reading Functions In Children, Chenglin Lou

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This thesis investigated associations between the white matter connectome and reading in children with a wide range of reading abilities. It is well established that the connectome supports the interplay among brain regions and connections within an integrated system. In this dissertation, I examine the hypothesis that it could therefore represent multiple mapping processes among reading components and further explain variations in reading performance. Such associations between the organization of the connectome and reading skills have not been well explored. This thesis aimed to address this issue by considering both the relationship between connectome measures and standardized reading performance out …

The Role Of Serotonin In The Estradiol-Dependent Selectivity Of Auditory Regions In Songbirds, Calista J. Henry

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Breeding-typical levels of estradiol in songbirds has been shown to lead to selective auditory processing and induce a release of serotonin in auditory regions of the forebrain. These findings triggered the question of whether auditory discrimination is driven by estradiol directly, or by the associated release of serotonin. I treated non-breeding female white-throated sparrows (Zonotrichia albicollis) with either blank implants, 17β-estradiol, serotonin enhancer and blank implants, or serotonin antagonist and 17β-estradiol implants. Birds then heard male conspecific songs or control tones, and ZENK-immunoreactivity was quantified in the caudomedial nidopallium (NCM) and caudomedial mesopallium (CMM). While I did not …

Fraction Magnitude Understanding Across Learning Formats: An Fmri Study, Chloe A. Henry

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Knowledge of fraction magnitudes are an important, but notoriously difficult mathematical concept to master. Behavioural work has begun to explore and compare the instructional tools used for fraction learning. However, how fraction instructional tools are processed in the brain remains an underexplored question. Therefore, in the present thesis, we used functional brain MRI methodology to examine the neural activity of adult participants while completing a fraction verification task using the number line and area model, two common methods of fraction learning. We found that both models commonly recruited fronto-parietal activity, the neural regions typically implicated in number processing. However, we …

Investigating The Roles Of The Dorsal And Ventral Striatum In Humor Comprehension And Appreciation Throughout Health, Aging, And Parkinson’S Disease, Maggie Prenger

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Humor processing is thought to involve two distinct components. The first, humor comprehension, involves detecting and resolving incongruities that are present within a humorous stimulus. This is related to cognitive processes such as ambiguity resolution, response inhibition, working memory, and cognitive flexibility, functions that are mediated in part by the dorsal portion of the striatum (DS). Humor appreciation, on the other hand, refers to the subjective amusement and mirth that one experiences in response to a joke. This is related to reward processing, which implicates the ventral portion of the striatum (VS). Across three separate studies, we investigated the involvement …

Perceptual Benefits From Long-Term Exposure To Naturalistic Sound Patterns, Bruno A. Mesquita

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Our brains are proficient in learning recurring structures in the environment, in order to optimize perceptual inferences based on relevant information in a stochastic input. Sensory information is multi-dimensional, and the relationship between sound dimensions may be, in itself, a source of information. Many sounds in our environment covary dynamically, and these covariances may be learned, and therefore shape our perception, through exposure to them in our natural environment. In the present study we investigate how natural (long term), and experimental (short term), learning of statistical regularities in sounds may shape our ability to categorize them (Experiment 1) and to …

The Effect Of Propionic Acid On The Habituation To Social And Non-Social Odour Cues In Adult Male Rats, Cashmeira-Dove P. Tyson

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The enteric bacterial metabolite, propionic acid (PPA), elicits physiological and behavioural changes in rodents reminiscent of autism spectrum disorder (ASD). This includes abnormal sensory processing and social behaviour. ASD may contribute to social deficits through impaired habituation; therefore, the present study examined the effects of intraperitoneal PPA on the habituation to social and non-social odours. Adult male rats were injected daily with PPA or the vehicle control, and for 3 days, habituated to a conspecific odour or vanilla extract for 10 minutes. On day 4, rats were exposed to a novel conspecific odour or almond extract for 10 minutes to …

Examining The Relationships Between Socio-Cognitive Factors And Neural Synchrony During Movie Watching Across Development, Kathleen M. Lyons

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While different cognitive abilities mature, the conscious experiences of children likely become richer and more elaborate. A challenge in investigating relationships between cognitive development and real-world experiences is having measures that assess naturalistic processing. Movie watching offers a solution, since following the plot of a film requires cognitive processes that are similar to real-world experiences. When different adults watch the same film, their brain activity begins to align (known as neural synchrony). The strength of this alignment has been shown to reflect the degree to which different individuals are having a similar experience of the movie. While this phenomenon has …

Role Of The Default-Mode Network During Narrative Integration In Major Depressive Disorder, Darren Ri-Sheng Liang

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How brain activity is synchronized across individuals during narrative comprehension has previously been characterized by functional magnetic resonance imaging (fMRI) in healthy and patient populations. To our knowledge, there has been limited investigation as to how it is affected by major depressive disorder (MDD). We addressed this issue with fMRI through examination of inter-subject synchronization in the default mode network (DMN), brain structures which have previously been implicated in MDD pathology. Twenty-two patients with MDD and 20 matched control participants listened to Intact versus Scrambled versions of an auditory narrative; these experimental conditions differed in the degree of temporal integration …

The Expression Of Guilt, Chloe A. Stewart

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Though aversive, the experience and expression of guilt is important to healthy social functioning. Guilt is often described as visceral, and nonverbal guilt expressions are anecdotally observed, yet much remains unknown about how guilt is expressed. The present work aimed to explore the visceral experience of guilt via the autonomic nervous system (ANS), and the nonverbal display of guilt via facial, gestural, and postural expressions. Using a novel film paradigm, we explored ANS activity during guilt in healthy adults and adults with neurodegenerative disorders (NDs). We further explored the nonverbal behaviours associated with guilt in healthy adults. We hypothesized that, …

Does Aberrant Connectivity Underlie The Experience Of Misophonia?, Kate Raymond

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Misophonia is a condition characterized by an extreme aversion to certain ordinary sounds, such as chewing or breathing. These sounds are typically innocuous but elicit strong feelings of anger, anxiety, and disgust as well as physiological stress in people with misophonia. This misophonic reaction to “trigger” sounds is also marked by increased activity in regions of the brain that process sound, ascribe salience, and regulate emotion (Kumar et al., 2017; Schroder et al., 2019). It has therefore been theorized that aberrant connectivity between these brain regions (particularly the anterior insula, auditory cortex, amygdala, and hippocampus) may underlie the experience of …

Is Motor Excitability Modulated By Isochronous Rhythms?, Syed Z. Raza

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Humans perceive and synchronize to regularity in auditory temporal sequences. Auditory regularity activates motor areas, but how the timing of motor responses relates to the regularity is unclear. Thus, we examined whether motor excitability, an index of motor activity, fluctuated to an isochronous sequence and characterized the timing of these fluctuations. Participants heard isochronous tones followed by a short silence, during which they imagined the tones continuing. Using single pulse transcranial magnetic stimulation (TMS), we indexed excitability throughout the sequence. Cosine models were fit to constructed excitability timecourses to quantify periodicity of the excitability fluctuations. Motor excitability did not fluctuate …

Feeling-Of-Knowing Experiences Breed Curiosity, Gregory Brooks

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It is well-established that curiosity has benefits for learning. Less is known about potential links between curiosity and memory retrieval. In theoretical work on metacognition it has been argued that retrieval experiences that occur during memory search can exert control over behaviour. States of curiosity, which can be defined as behavioural tendencies to seek out information, may play a critical role in this control function. We conducted two experiments to address this idea, focusing on links between feeling-of knowing (FOK) experiences, memory-search duration, and subsequent information-seeking behaviour. We administered an episodic FOK paradigm that probed memory for previously studied arbitrary …

Understanding The Effects Of Physical Activity On Executive Functioning And Psycho-Emotional Well-Being In Children With Adhd, Hannah B. Bigelow

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A short bout of physical activity has been shown to improve executive functioning in children. However, the implications for children with Attention Deficit Hyperactivity Disorder (ADHD) has been understudied. We examined the impact of a 10min bout of physical activity on executive functioning and psycho-emotional well-being in children with ADHD. Participants engaged in two lab-based sessions separated by 1-week: a physical activity session and a control session. The physical activity session included a 10min bout of moderate-intensity biking, with a pre-post battery of cognitive and psycho-emotional assessments. The control session consisted of 10mins of silent reading. We used functional imaging …

Putting 'Dopamine Overdose' To The Test: A Psychopharmacological Investigation In Parkinson's Disease And Healthy Volunteers, Andrew Vo

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Dopaminergic therapy prescribed to address motor symptoms in Parkinson’s disease (PD) is done at the expense of some cognition functions. It has been hypothesized that whether a given function is improved or impaired by medication depends on the baseline dopamine levels within underlying brain regions. Areas most affected by PD and severely dopamine depleted are predicted to benefit from dopaminergic therapy. Regions with less dopamine deficiency are predicted to worsen from excessive dopamine stimulation. This theoretical framework is known as the dopamine overdose hypothesis. The central aim of this thesis was to critically test the straightforward predictions put forward by …

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

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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). …

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 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, …

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 …

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 …

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, …

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 …