Naznin Virji-Babul
Relevant Thesis-Based Degree Programs
Affiliations to Research Centres, Institutes & Clusters
Biography
Dr. Virji-Babul is a physical therapist and a neuroscientist. Her Lab (Brain Development: Perception to Action) uses a combination of behavioural and brain imaging tools (i.e. DTI and EEG) to probe the brain and investigate the patterns of brain activation as they relate to perceptual-motor and social-emotional development in children and youth. Dr. Virji-Babul also has a strong research focus on concussion in adolescents. Her goals are to develop sensitive, multimodal measures of brain injury that can be used for early diagnosis and use these measures to chart the recovery process following concussion. Dr. Virji-Babul works collaboratively with faculty in Engineering, Physics, Mathematics and Statistics and in the Developmental Neurosciences and Child Health Cluster at the BC Children's Hospital Research Institute.
Graduate Student Supervision
Doctoral Student Supervision
Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
Soccer players are exposed to a high number of repetitive head impacts (RHIs), which have been hypothesized to lead to cumulative brain trauma. Studies have utilized a variety of methods to estimate exposure to RHIs including self-report, direct observation, modified video analysis and head impact sensors. Such measurements have previously only been done for select events and participants or have relied heavily on memory leading to potential sampling bias and limited understanding of total exposure. Additionally, due to methodological inconsistencies and sex-based differences, previous research has remained inconclusive on potential brain function and health-related changes due to RHIs. This dissertation contains five interconnected studies on female athletes. The first uses encephalography (EEG) and health-related metrics to compare non-contact athletes to soccer players with and without concussions. This chapter establishes that while soccer players without a concussion demonstrate differences to non-contact athletes, they do not demonstrate significant changes compared to soccer players with a concussion. The next chapter demonstrates that soccer players routinely overestimate the number of head impacts experienced in both games and practices. We establish the unreliability of self-report to estimate exposure and suggest video data be used to objectively quantify absolute head exposure. The third chapter is a comprehensive analysis of three years’ worth of video footage to quantify heading frequency. We demonstrate significant inter-player variability withing a single team and demonstrate the necessity of including training sessions, in addition to games, when representing player RHI exposure levels. The fourth chapter quantifies the magnitude of individual head impacts through custom fitted mouthpieces with an accelerometer and gyroscope. We demonstrate which impact scenarios produce the highest kinematics and therefore, which scenarios may pose higher risk. Chapter three and four illustrate the need to study both frequency and magnitude of RHI in research. The final chapter revisits the use of EEG and health-related metrics to evaluate the influence of heading on brain function and behaviour. We demonstrate a potential dose-response between the number of head impacts and resulting changes. Results from these studies contribute to the growing scientific knowledge surrounding RHIs and sets a structure for future quantification of RHIs.
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The first year of life is a period of dramatic structural changes in the brain. Along with structural changes, infants achieve significant behavioral milestones. The bridge between brain structure and behavior is strongly based on functional connections that enable intrinsic functioning and also develop emotion perception skills, both critical for early development. However, little is known about how these connections are functionally organized in infancy. Prenatal exposures to maternal mood disturbances and the use of selective serotonin reuptake inhibitor (SSRI) antidepressants play a crucial role in shaping infants’ development, although it remains unclear how these exposures are linked to infant developmental outcomes. In this thesis, I use task-based electroencephalography (EEG) and resting-state functional magnetic resonance imaging (rs-fMRI) combined with graph theory analysis to study the functional networks of emotion perception and the intrinsic functional connectivity of resting state networks (RSNs) in typically developing infants and in infants prenatally exposed to mood disturbances and SSRIs. I found that 8-to-10-month-old infants have network characteristics that are similar to adults when observing basic emotions (Chapter 3). Moreover, an increase in prenatal maternal mood symptoms was associated with reduced modularity only for negative emotions, while prenatal SSRI drug-exposure was associated with higher network modularity in observing both positive and negative emotions. In contrast, higher postnatal mood symptoms were associated with alterations in frontal hubs (Chapter 5). Prenatal mood disturbances were associated with alterations in intrinsic RSNs. Specifically, compared to the control group, infants exposed to prenatal maternal depression showed higher hub values of the left anterior-cingulate, insula, and caudate as well as higher hub values in the amygdala (Chapter 7). Prenatal SSRI exposure associated both with higher hub values in Heschel’s gyrus (Chapter 7) and with hyperconnectivity of the putative auditory network (Chapter 6) possibly support shifts in language perception previously reported in infants exposed to prenatal SSRI. Collectively, these data indicate that the core functional organization for observing basic emotions is in place at 8-to-10 months of age. Further, maternal mood disturbances and SSRI exposure may differently shape early intrinsic and emotion perception functional organization, possibly leading to different developmental trajectories.
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Master's Student Supervision
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
Concussion is a complex and dynamic injury that involves alterations in brain function. This can present clinically as post-concussive symptoms and exercise intolerance. However, functional brain changes can extend beyond the point of clinical recovery. This can lead to increased brain vulnerability when returning to play as complete physiological recovery has not yet been achieved. Neuroimaging techniques such as Electroencephalography (EEG) can quantify functional brain changes that are present after sustaining a concussion. Despite advances in neuroimaging techniques, there is a paucity of research evaluating the effect exercise has on brain function following a concussion. The aim of this feasibility study was to evaluate functional brain changes as measured by EEG spectral power in a group of concussed participants in comparison to healthy controls before and after performing a clinical exertion test entitled the Buffalo Concussion Bike Test (BCBT). A secondary aim was to evaluate behavioral differences between the two groups. The study consisted of five concussed and five control participants. Results revealed increased power in the 1-14 frequency range (delta, theta, alpha and low beta) in frontal brain regions of the concussed group in comparison to controls before and after performing the BCBT. EEG data collection was on average 90 to 120 minutes in duration and data quality was high for the majority of participants (83%). Three concussed participants failed the BCBT due to exceeding heart rate criteria, one failed due to symptom increase and one passed the test. Results indicate the feasibility of EEG spectral power as a measure of functional brain changes post-concussion, however the BCBT may not be a suitable concussion exertion protocol for a non-athlete population. For behavioral measures, we found clear group differences when comparing results between concussed and control groups.
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Repeated physical practice is not always the optimal approach in rehabilitation, especially in individuals with severe motor-related problems. Research has shown the effectiveness of observational practice as a motor learning tool in various rehabilitation settings. However, little is known about the neurophysiological mechanisms underlying this mode of learning and whether similar behavioral and neurophysiological changes occur during physical and observational practice. The purpose of this study was to compare short-term physical and observational practice during the acquisition and retention of a novel motor task and to evaluate how each type of practice modulates EEG mu rhythm (8-13Hz). Thirty healthy individuals were randomly assigned to one of three groups: (1) physical practice (PP); (2) observational practice (OP); and (3) no practice (NP). The experiment consisted of three phases: training, testing (observing 10 minutes following training), and retention (performing 24 hours following training). Two behavioural measures (as indexed by total time and error) and brain responses (as indexed by mu suppression at the central regions) were examined. The results revealed: (1) that when comparing the PP group during their first exposure to the task to the OP group during their first exposure to the task, the OP group was significantly faster than the PP group, did not differ from the PP group in terms of error, (2) significant bilateral suppression of mu rhythm during PP and significant left lateralized mu suppression during OP, (3) significant bilateral mu suppression during observation after PP compared to that after OP and NP. Overall, the study demonstrates that OP induces neurophysiological (i.e., mu suppression) and behavioural (i.e., reduced total time) changes similar to that occur during PP. However, the different pattern of activation during the two types of practice suggests that OP does not activate the same brain areas activated during PP; rather, it triggers a subset of brain regions. Therefore, OP may be a good proxy for PP under conditions where PP is not possible. This is the first study to investigate changes in mu rhythm as a function of both PP and OP.
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Returning to play following a sports related concussion remains a controversial process due to the emphasis placed on subjective symptom reporting. The development of an objective measure capable of assessing cortical recovery remains elusive, however EEG has shown promise with its ability to record during exercise. The objective of this pilot study was to examine the association between EEG metrics and behavioural changes in healthy young adults.The study involved 13 participants who performed a novel graded working memory task, a graded exercise session and a task combining the two together while EEG was recorded over 3 separate sessions. The tasks consisted of 5 levels of increasing difficulty and each participant performed the tasks in a randomized order. Participant heart rate, perceived exertion and accuracy were recorded between levels and tasks. EEG analysis applied power spectrum analysis and graph theoretical analysis to identify cortical activity and cortical networks changes.When graded exercise and cognition were combined, there was a significant change in behaviour and neural activity compared to when each task was completed individually. The combined task led to significant changes in brain and behavior as seen in EEG activation pattern, power output and frontal functional connectivity measures.These results suggest that following sports-related concussion individuals would require increased neural resources to complete a combined cognitive and exercise task. Following injury, these additional resources may not be available and result in a decrease in task performance. This data has the potential to be used in addition to existing concussion recovery tests in assuring full recovery prior to the return to play.
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BACKGROUND: The mirror neuron system (MNS) is a neurological network associated with action-perception coupling, and is influenced by previous experiences. Visual, auditory, multi-modal, congruent and incongruent stimuli have been shown to modulate the response of the MNS throughout the various stages of human development. The musical attribute of tempo may exert a specific influence on action perception but this has not been studied in children. PURPOSE: The overarching purpose of this research is to explore the neurological interactions of music and action. This study asks the question, “How does the tempo of regular pulse influence perception of action in children?”METHODS: This research reflected on music and the MNS within the framework of dynamic systems theory (DST). A literature review examined the research relevant to the study question. Finally, a pilot study compared the responses in the MNS of 10 children during exposure to stimuli with tempi of 40 beats per minute (BPM) and 173BPM by examining the relative power of the mu rhythm frequency band (8-13Hz) in the sensorimotor cortex.RESULTS: Previous research suggests tempo significantly influences executed movements, cortical excitability, perception of emotion in music, and perception of synchrony in audio-visual stimuli. The pilot study identified significant mu suppression in the left sensorimotor cortex during visual conditions only, whereas the right sensorimotor cortex demonstrated significant mu suppression during auditory, visual and multi-modal conditions. In the left hemisphere, visual stimuli showed significantly greater mu suppression than auditory stimuli. In the right hemisphere, visual stimuli with a tempo of 173BPM showed significantly greater mu suppression than auditory stimuli with a tempo of 40BPM. The covariates of age, musical experience and dance experience were identified to have significant interactions with conditions.CONCLUSIONS: This pilot study provided the first evidence that visual stimuli result in stronger mu suppression compared to auditory stimuli in typically developing children, similar to that found in adults. Increased tempo was associated with stronger action-perception coupling for uni-modal stimuli. This study lacked statistical power to demonstrate differences between multi-modal stimuli exhibiting equivalent or differing tempi; further research with larger samples is needed to explore these influences.
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