Browsing by Author "Goodyear, Bradley G."
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- ItemOpen AccessAge-dependent analysis of cerebral structures and arteries in a large database(2022-06-30) Mouches, Pauline; Forkert, Nils D.; Goodyear, Bradley G.; Josephson, Colin B.Aging of the population is expected to lead to a rapid increase of neurological diseases. Such diseases can progress quickly and detrimentally affect the daily life of patients. Prognosis improves with early diagnosis, but early detection is diffcult. It is crucial to be able to differentiate early stage pathological alteration from normal age-related changes. Thus, there is a need for a better understanding of brain aging and reliable biomarkers. Within that context, the overarching aim of this work is to study normal aging patterns in brain tissues and arteries using a large database of magnetic resonance imaging and angiography data, as well as cardiovascular risk factors from the whole adult life span. To do so, the objectives of this thesis are: (1) to quantify artery morphology variability among adults and identify the impact of age, sex and cardiovascular risk factors on cerebrovascular structures; (2) to combine brain tissue and artery information for biological brain age prediction; (3) to explore the impact of cardiovascular risk factors on the brain age gap, which is a biomarker representing the difference between the biological brain age and chronological age. To achieve these objectives, first, a statistical cerebrovascular atlas is generated from multi-centre adult data. Image analyses and multivariate regression methods are then employed to find associations between brain artery morphology and aging. Second, multi-modal explainable deep learning models are used to accurately estimate the biological brain age and identify predictive brain regions. Third, an exploratory causal analysis is performed to isolate the effects of individual factors on the brain age gap. The results of this work offer a novel insight on brain tissue and artery aging patterns. An in-depth analysis of the brain age gap biomarker is carried out. Novel approaches are proposed to improve brain age prediction models in terms of accuracy and explainability. Finally, innovative methods are used to study cause and effects relationships between brain aging and cardiovascular risk factors. This work aims to uncover clinically relevant findings and represents valuable methodological advancements that could be used in other neuroimaging clinical applications, for instance, to ameliorate predictive models for decision-support.
- ItemOpen AccessControversial Topics in Gambling: Alberta Gambling Research Institute's 13th Annual Conference(2014-04-14) Aitchison, Katherine J.; Castellani, Brian; Chapman, Craig S.; Christensen, Darren R.; Crawford, Sandy; Currie, Cheryl; Downs, Carolyn; Euston, David; Forrest, David; Goodyear, Bradley G.; Gruber, Aaron; Hanson, William; Hodgins, David C.; Scholnick, Barry; Schopflocher, Don; Schrans, Tracy; Simpson, Rob; Singhal, Anthony; Spetch, Marcia L.; Smith, Garry; Suomi, Aino; Walker, Gordon; Williams, RobertThe Alberta Gambling Research Institute and the University of Alberta co-sponsored the thirteenth in a series of special interest conferences in the area of gambling studies. The conference theme was "Controversial Topics in Gambling." The conference took place Thursday, April 3, Friday, April 4, & Saturday, April 5, 2014 at the Banff Centre.
- ItemOpen AccessFunctional connectivity of neural motor networks is disrupted in children with developmental coordination disorder and attention-deficit / hyperactivity disorder(Elsevier, 2014) McLeod, Kevin R.; Langevin, Lisa Marie; Goodyear, Bradley G.; Dewey, Deborah
- ItemOpen AccessFunctional Near-Infrared Spectroscopy Reveals Reduced Interhemispheric Cortical Communication after Pediatric Concussion(Mary Ann Liebert, 2015-06-01) Ubran, Karolina J.; Barlow, Karen M.; Jimenez, Jon J.; Goodyear, Bradley G.; Dunn, Jeffrey F.Concussion, or mild traumatic brain injury (mTBI), is a growing concern, especially among the pediatric population. By age 25, as many as 30% of the population are likely to have had a concussion. Many result in long-term disability, with some evolving to postconcussion syndrome. Treatments are being developed, but are difficult to assess given the lack of measures to quantitatively monitor concussion. There is no accepted quantitative imaging metric for monitoring concussion. We hypothesized that because cognitive function and fiber tracks are often impacted in concussion, interhemispheric brain communication may be impaired. We used functional near-infrared spectroscopy (fNIRS) to quantify functional coherence between the left and right motor cortex as a marker of interhemispheric communication. Studies were undertaken during the resting state and with a finger-tapping task to activate the motor cortex. Pediatric patients (ages 12–18) had symptoms for 31–473 days, compared to controls, who have not had reported a previous concussion. We detected differences between patients and controls in coherence between the contralateral motor cortices using measurements of total hemoglobin and oxy-hemoglobin with a p < 0.01 (n = 8, control; n = 12 mTBI). Given the critical need for a quantitative biomarker for recovery after a concussion, we present these data to highlight the potential of fNIRS coupled with interhemispheric coherence analysis as a biomarker of concussion injury.
- ItemOpen AccessIdentifying the Seizure Onset Zone using Intracranial EEG-fMRI(2018-09-18) Mohammadi, Negar; Federico, Paolo; Agha-Khani, Yahya; Goodyear, Bradley G.; Scantlebury, Morris H.; Sotero Díaz, Roberto C.Simultaneous EEG-fMRI has been an effective technique for identification of the seizure onset zone (SOZ) in patients with refractory epilepsy. Recent studies have shown that using intracranial electrodes (iEEG) combined with fMRI offers unique insight into changes in blood oxygen-level dependent (BOLD) responses associated with interictal epileptiform discharges (IEDs). However, the concordance level between SOZ and IED-related BOLD clusters has not been quantitatively investigated for different brain structures. This thesis aims to identify patient-specific concordance levels between spike-associated BOLD clusters and IED/SOZ originating from temporal and extra-temporal structures. The distances between the BOLD clusters to IED/SOZ locations were measured for 15 patients with focal refractory epilepsy. The results showed that the spike-generating network was better delineated in patients with temporal discharges compared to those with extra-temporal discharges. Also, we observed shorter distances between the BOLD clusters and the SOZ for mesial temporal lobe seizures compared to frontal lobe seizures. Further investigation into the differences between mesial temporal and frontal structures showed that patients with focal impaired awareness seizures had significantly higher concordance for mesial temporal lobe seizures. This key finding suggests that mesial temporal structures limit spike-associated BOLD activation to the SOZ more than the frontal lobe in patients who have spread of ictal activity to subcortical arousal systems. This mechanistic difference was also complemented by our findings pertaining seizure frequency. Specifically, concordance levels in temporal lobe structures were significantly higher for patients with weekly seizures compared to extra-temporal structures. Based on these findings, we suggest that iEEG-fMRI is a useful technique for identifying seizure onset zone for patients with epileptic spikes and seizures originate in the mesial temporal structures. The work presented in this thesis may assist clinicians to better determine the seizure onset zone, guide epilepsy surgery, and improve post-surgical outcomes for epilepsy patients.
- ItemOpen AccessMultimodal Imaging of Cortical Networks Controlling Lower Limb Locomotion: Towards the Development of Brain-Computer Interfaces(2018-07-11) Kline, Adrienne; Ronsky, Janet L.; Goodyear, Bradley G.; Forkert, Nils Daniel; Syed, Naweed L.In 2015 the National Spinal Cord Injury Association of Canada reported that 30,000 Canadians suffer from paralysis in two or more limbs. In many cases this takes away the fundamental ability to walk. Walking, an intricate sensorimotor task, involves the interactions of both dynamic and balancing neurological processes. Brain computer interfaces (BCIs) are attempting to bridge the gap that will allow persons with compromised mobility to interact with the world via control of prosthetic devices that can ‘act’ by using solely neural input (i.e. thoughts). The goal of this thesis was to aid in the development of a BCI for lower limb locomotion by identifying similarities and differences between cortical activity associated with executed and imagined left and right lower limb movements using electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI). Data from 16 participants showed that it was possible to differentiate between right versus left executed and imagined thought processes for lower limb locomotion using solely information from an EEG, and that these patterns of brain activity were generalizable across time points and trials. It was also found, through the use of fMRI, that areas of brain activation in executed and imagined conditions were similar for some areas but showed unique activation areas as well. A novel paradigm to co-register EEG and fMRI data was developed that can easily be utilized in other contexts. Finally, using EEG and fMRI data allowed for an efficient model to use in a machine learning paradigm that successfully predicted left versus right lower limb movement. This research adds to the existing body of knowledge in understanding psychomotor brain activity associated with thought coordination processes involved in the task of walking in normal persons represented by algorithmic patterns.
- ItemOpen AccessNovel Functional Magnetic Resonance Imaging Analysis Approaches for Investigations of the Dynamics of Resting-State Functional Connectivity(2018-08-23) Sojoudi, Alireza; Goodyear, Bradley G.; Smith, Michael Richard; Dukelow, Sean P.; MacIntosh, Bradley; MacMaster, Frank P.; Sotero Díaz, RobertoSpontaneous fluctuations of blood-oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI) signals are highly synchronous between brain regions that serve similar functions. This provides a means to investigate functional networks of the human brain; however, most data analysis techniques assume functional connections are constant over time. This is problematic when studying brain processes associated with aging or neurological disease, where functional connections may become highly variable. Proposed methods of examining moment-to-moment changes in the strength of functional connections over an imaging session (so called dynamic connectivity) are not well established, and there are several pitfalls in current analysis approaches. In this thesis, novel analysis frameworks are developed to address several issues associated with dynamic resting-state fMRI analysis techniques. These techniques are then used to analyze the dynamics of functional connectivity within long-range and local brain networks. Specifically, a hierarchical observation modeling approach is proposed to permit statistical inference of the presence of dynamic connectivity at any point in time. Also, a sliding-window regional homogeneity approach is developed to examine the dynamics of local functional connectivity, to gain even further insight into the global functional organization of the human brain. Finally, the proposed methods are used in a study to determine resting-state local and long-range connectivity changes related to healthy aging, and further, how these changes demonstrate that age changes the proportion of time the brain occupies certain functional states. The studies in this thesis greatly further our understanding of the functional architecture of the human brain, in terms of how local and long-distance interactions are organized both in space and time. This thesis also helps establish a framework for dynamic resting-state fMRI analysis with consistency and reliability.
- ItemOpen AccessReward Neurocircuitry in Autism Spectrum Disorder(2018-09-14) Schuetze, Manuela; Bray, Signe L.; Kennedy, Dan; Graham, Susan A.; Borgland, Stephanie Laureen; Goodyear, Bradley G.; Dewey, DeborahAutism spectrum disorder (ASD) is a common neurodevelopmental disorder with social impairments and restricted interests. Early behavioural interventions often focus on reinforcing desired behaviours (e.g., eye contact) and reducing atypical behaviours (e.g., echoing others' phrases). A recent framework suggests reward system dysfunction to be at the core of ASD symptoms. However, if the reward system is impaired in ASD, it is paradoxical that reward-based strategies are commonly used during interventions. The goal of this thesis was to investigate the reward neurocircuitry to explore whether reward system dysfunction contributes to the ASD phenotype. We conducted a literature review on physiological, behavioural, and neural responses to reinforcers to look for common atypical patterns across all domains. We then investigated structural changes in basal ganglia and the thalamus using advanced surface-based methodology. For this, we modelled effects of diagnosis, age, and their interaction on volume, shape, and surface area on T1-weighted anatomical images of 373 male participants with ASD and 384 typically developing (TD). Finally, we investigated neural responses in the context of learning using rewards that were tailored to participants’ unique interests. 27 adolescents with ASD and 31 TD adolescents performed a reinforcement learning task while we collected fMRI data. Participants had to learn which of two doors showed images of their personal interests. The literature review revealed no consistent pattern of atypical reward responses in ASD. Further, we found that subcortical regions did not differ in volume between individuals with and without ASD. However, we found localized structural changes in shape and surface area of the putamen, globus pallidus and thalamus. Some changes were modulated by age, IQ and symptom severity. Interestingly, when using personal interests as reinforcers during a learning task, we found intact learning performance and similar neural responses in the reward system between ASD and TD groups. Taken together, mixed findings from the literature review and subtle structural changes in subcortical regions of the reward system suggest a role of this neurocircuitry in the ASD phenotype. However, intact learning and typical neural responses towards individual interests suggest that the reward system is not generally impaired in ASD.
- ItemOpen AccessThalamic Nuclei Localization Using fMRI for Image-Guided Thalamotomy in Movement Disorders(2018-09-04) Shie, Nancy; Pike, G. Bruce; Goodyear, Bradley G.; Sotero Díaz, Roberto C.Thalamotomy and deep brain stimulation (DBS) are important surgical options for patients with tremor-dominant movement disorders. They have provided significant improvements to those with Parkinson’s disease (PD), essential tremor (ET), and dystonic tremor (DT) in their daily quality of life. Both neurosurgery techniques require presurgical imaging to localize targets for electrode placement. The thalamus is a common target for patients with uncontrollable tremor. It is made up of multiple, irregularly shaped nuclei with vague and almost indistinguishable topographies. Improving the localization of these nuclei prior to electrode implantation can potentially reduce surgery times and increase success rates. The use of magnetic resonance imaging (MRI) allows us to study soft tissue structures, such as the brain, noninvasively, with high resolution, and without using ionizing radiation. More recently, the functional activity and connections within the brain can be visualized using MRI sequences that detect signals highly correlated with neuronal activity, a technique called functional MRI (fMRI). In this thesis we aimed to localize specific thalamic nuclei using fMRI, by looking at task-based activations (TB-fMRI) and functional connections in the resting state (RS-fMRI), between the thalamus and the sensory and motor cortices in ET and tremor-dominant PD patients, as well as in healthy controls. Results showed that TB-fMRI and RS-fMRI each localized the motor regions of the thalamus to >10mm from expected motor thalamus locations obtained from surgical lesion locations and literature reported locations. There were no differences in localized motor thalamus locations between groups using either fMRI technique. However, the motor thalamus was more distinctly separated from the sensory thalamus using TB-fMRI. This may ultimately result in a more accurate thalamic mapping process prior to thalamic lesioning or DBS electrode implantation, shorten resulting surgical times and improve overall surgical outcome.