Life Sciences Commons^™

The Neural Mechanisms Of Musical Rhythm Processing: Cross-Cultural Differences And The Stages Of Beat Perception, Daniel J. Cameron

Electronic Thesis and Dissertation Repository

Music is a universal human behaviour, is fundamentally temporal, and has unique temporal properties. This thesis presents research on the cognitive neuroscience of the temporal aspects of music: rhythm, beat, and metre. Specifically, this work investigates how cultural experience influences behavioural and neural measures of rhythm processing, and the different neural mechanisms (with particular interest in the role of the striatum) that underlie different stages of beat perception, as musical rhythms unfold.

Chapter 1 presents an overview of the existing literature on the perceptual, cognitive, and neural processing of rhythm, including the entrainment of neural oscillations to rhythm and the …

Role Of Anterior Cingulate Cortex In Saccade Control, Sahand Babapoor-Farrokhran

Electronic Thesis and Dissertation Repository

Cognitive control is referred to the guidance of behavior based on internal goals rather than external stimuli. It has been postulated that prefrontal cortex is mainly involved in higher order cognitive functions. Specifically, anterior cingulate cortex (ACC), which is part of the prefrontal cortex, is suggested to be involved in performance monitoring and conflict monitoring that are considered to be cognitive control functions.

Saccades are the fast eye movements that align the fovea on the objects of interest in the environment. In this thesis, I have explored the role of ACC in control of saccadic eye movements. First, I performed …

Contribution Of The Primate Frontal Cortex To Eye Movements And Neuronal Activity In The Superior Colliculus, Tyler R. Peel

Electronic Thesis and Dissertation Repository

Humans and non-human primates must precisely align the eyes on an object to view it with high visual acuity. An important role of the oculomotor system is to generate accurate eye movements, such as saccades, toward a target. Given that each eye has only six muscles that rotate the eye in three degrees of freedom, this relatively simple volitional movement has allowed researchers to well-characterize the brain areas involved in their generation. In particular, the midbrain Superior Colliculus (SC), is recognized as having a primary role in the generation of visually-guided saccades via the integration of sensory and cognitive information. …

Is Online Motor Control Really Impaired In Parkinson's Disease?, Kate E. Merritt

Electronic Thesis and Dissertation Repository

Patients with Parkinson’s disease (PD) are thought to be selectively impaired in consciously-mediated online automatic motor control, whereas the ability to perform subconscious online adjustments remains intact. This present study evaluates the hypothesis that the previously alleged deficits in online motor control in PD are not due to the consciousness of the correction, but rather are attributable to aspects of the prior experimental designs disproportionately penalizing patients for PD-related bradykinesia. Here, we implemented a modified traditional double-step paradigm to investigate consciously-mediated online motor control in PD, in a manner that would be unconfounded by disease-related bradykinesia. Further, we investigated the …

Spatial Memory In Black-Capped Chickadees: Studies Of Adult Hippocampal Neurogenesis And Win-Shift/Win-Stay Spatial Search, Nicole Ann Guitar

Electronic Thesis and Dissertation Repository

Two cognitive adaptations were studied in Black-capped chickadees through tests of adult hippocampal neurogenesis and Win-shift/Win-stay spatial search. Neurogenesis has been proposed to aid memory, therefore it was hypothesized that birds with decreased neurogenesis would perform poorer than controls in hippocampal-dependent spatial working and reference memory tasks followed by a reversal. Subjects with decreased neurogenesis, caused by the neurotoxin MAM, reversed slower than controls, suggesting that neurogenesis may contribute to differentiating similar memories, although this effect was nonsignificant. Win-shift/Win-stay foraging behavior is an adaptation to the replenishing and depleting nature of food. Since chickadees forage on food that depletes quickly …

Unravelling The Subfields Of The Hippocampal Head Using 7-Tesla Structural Mri, Jordan M. K. Dekraker

Electronic Thesis and Dissertation Repository

Probing the functions of human hippocampal subfields is a promising area of research in cognitive neuroscience. However, defining subfield borders in Magnetic Resonance Imaging (MRI) is challenging. Here, we present a user-guided, semi-automated protocol for segmenting hippocampal subfields on T2-weighted images obtained with 7-Tesla MRI. The protocol takes advantage of extant knowledge about regularities in hippocampal morphology and ontogeny that have not been systematically considered in prior related work. An image feature known as the hippocampal ‘dark band’ facilitates tracking of subfield continuities, allowing for unfolding and segmentation of convoluted hippocampal tissue. Initial results suggest that this protocol offers sufficient …

The Effects Of Concurrent Cognitive Load On The Processing Of Clear And Degraded Speech, Harrison Ritz

Electronic Thesis and Dissertation Repository

A previous study has found that perceiving degraded speech requires attention, with compromised behavioral and neurological measures of speech processing for degraded speech, but not clear speech, when participants are distracted (Wild et al., 2012b). We extended these findings by examining behavioral and neural correlates of speech perception under different levels of cognitive load using multiple object tracking. We also investigated the role of attention in perceiving degraded speech that was as intelligible as clear speech, in order to separate perceptual outcomes (i.e., intelligibility) from the requisite processing demands. We found that the speech perception system is heterogeneous in its …

Pharmacogenetics Of Non-Motor Symptoms In Parkinson's Disease, Brian Robertson

Electronic Thesis and Dissertation Repository

Memory deficits are recognized in Parkinson’s disease (PD). The nature of these memory deficits is unclear because few studies have both isolated memory encoding and retrieval processes while testing patients on and off their dopamine replacement medication. Previous work suggests encoding depends upon regions innervated by the ventral tegmental area, which is relatively spared in PD, while retrieval depends upon dorsal striatum, which is dopamine deficient even early in PD. We investigated the impact of a dopamine transporter (DAT1), a dopamine reuptake protein, polymorphism (a 40-base-pair variable repeat affecting expression) on encoding and retrieval in healthy, elderly controls as well …

The Role Of Forebrain Cholinergic Signalling In Regulating Hippocampal Function And Neuropathology, Mohammed Al-Onaizi

Electronic Thesis and Dissertation Repository

Cholinergic dysfunction has been associated with cognitive abnormalities in a variety of neurodegenerative and neuropsychiatric disorders, including Alzheimer’s Disease (AD). Cumulative use of drugs with anticholinergic activity is associated with increased risk for dementia and AD. Also, cholinergic function has been implicated in predicting the development of key neuropathological hallmarks seen in AD. However, the relationship between cholinergic dysfunction and conservation of cognitive ability as well as neuronal cell maintenance is not fully understood. Here, we tested how information processing and distinct molecular mechanisms associated with AD are regulated by cholinergic tone in genetically-modified mice in which cholinergic transmission was …

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

Electronic Thesis and Dissertation Repository

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 …

Classifying Music Perception And Imagination Using Eeg, Avital Sternin

Electronic Thesis and Dissertation Repository

This study explored whether we could accurately classify perceived and imagined musical stimuli from EEG data. Successful EEG-based classification of what an individual is imagining could pave the way for novel communication techniques, such as brain-computer interfaces. We recorded EEG with a 64-channel BioSemi system while participants heard or imagined different musical stimuli. Using principal components analysis, we identified components common to both the perception and imagination conditions however, the time courses of the components did not allow for stimuli classification. We then applied deep learning techniques using a convolutional neural network. This technique enabled us to classify perception of …

Cannabinoid Cb1 Transmission In The Mesolimbic Reward Pathway, Tasha Ahmad

Electronic Thesis and Dissertation Repository

Cannabinoid CB1 receptor (CB1R) transmission within the mesocorticolimbic system plays an important role in forming associative memories, and processing both positive and negative experiences. Opiates generally produce potent rewarding effects and previous evidence suggests that CB1 transmission may modulate the neural reward circuitry involved in opiate reward processing. The ventral tegmental area (VTA), medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and Nucleus Accumbens (NA) are all implicated in opiate-reward processing, contain high levels of CB1 receptors, and are all modulated by dopamine (DA). Although, CB1 transmission within these areas has been heavily implicated in associative memory and learning, the potential …