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Mary Lou Smith

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6 papers

1 author row

YNICL Journal 2019 Journal Article

White matter microstructural differences identified using multi-shell diffusion imaging in six-year-old children born very preterm

Julia M. Young
Marlee M. Vandewouw
Sarah I. Mossad
Benjamin R. Morgan
Wayne Lee
Mary Lou Smith
John G. Sled
Margot J. Taylor

INTRODUCTION: The underlying microstructural properties of white matter differences in children born very preterm (<32 weeks gestational age) can be investigated in depth using multi-shell diffusion imaging. The present study compared white matter across the whole brain using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) metrics in children born very preterm and full-term children at six years of age. We also investigated associations between white matter microstructure with early brain injury and developmental outcomes. METHOD: Multi-shell diffusion imaging, T1-weighted anatomical MR images and developmental assessments were acquired in 23 children born very preterm (16 males; mean scan age: 6.57 ± 0.34 years) and 24 full-term controls (10 males, mean scan age: 6.62 ± 0.37 years). DTI metrics were obtained and neurite orientation dispersion index (ODI) and density index (NDI) were estimated using the NODDI diffusion model. FSL's tract-based spatial statistics were performed on traditional DTI metrics and NODDI metrics. Voxel-wise comparisons were performed to test between-group differences and within-group associations with developmental outcomes (intelligence and visual motor abilities) as well as early white matter injury and germinal matrix/intraventricular haemorrhage (GMH/IVH). RESULTS: In comparison to term-born children, the children born very preterm exhibited lower fractional anisotropy (FA) across many white matter regions as well as higher mean diffusivity (MD), radial diffusivity (RD), and ODI. Within-group analyses of the children born very preterm revealed associations between higher FA and NDI with higher IQ and VMI. Lower ODI was found within the corona radiata in those with a history of white matter injury. Within the full-term group, associations were found between higher NDI and ODI with lower IQ. CONCLUSION: Children born very preterm exhibit lower FA and higher ODI than full-term children. NODDI metrics provide more biologically specific information beyond DTI metrics as well as additional information of the impact of prematurity and white matter microstructure on cognitive outcomes at six years of age.

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YNIMG Journal 2016 Journal Article

Thinking about the thoughts of others; temporal and spatial neural activation during false belief reasoning

Sarah I. Mossad
Michelle AuCoin-Power
Charline Urbain
Mary Lou Smith
Elizabeth W. Pang
Margot J. Taylor

Theory of Mind (ToM) is the ability to understand the perspectives, mental states and beliefs of others in order to anticipate their behaviour and is therefore crucial to social interactions. Although fMRI has been widely used to establish the neural networks implicated in ToM, little is known about the timing of ToM-related brain activity. We used magnetoencephalography (MEG) to measure the neural processes underlying ToM, as MEG provides very accurate timing and excellent spatial localization of brain processes. We recorded MEG activity during a false belief task, a reliable measure of ToM, in twenty young adults (10 females). MEG data were recorded in a 151 sensor CTF system (MISL, Coquitlam, BC) and data were co-registered to each participant's MRI (Siemens 3T) for source reconstruction. We found stronger right temporoparietal junction (rTPJ) activations in the false belief condition from 150ms to 225ms, in the right precuneus from 275ms to 375ms, in the right inferior frontal gyrus from 200ms to 300ms and the superior frontal gyrus from 300ms to 400ms. Our findings extend the literature by demonstrating the timing and duration of neural activity in the main regions involved in the “mentalizing” network, showing that activations related to false belief in adults are predominantly right lateralized and onset around 100ms. The sensitivity of MEG will allow us to determine spatial and temporal differences in the brain processes in ToM in younger populations or those who demonstrate deficits in this ability.

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YNIMG Journal 2015 Journal Article

Deep grey matter growth predicts neurodevelopmental outcomes in very preterm children

Julia M. Young
Tamara L. Powell
Benjamin R. Morgan
Dallas Card
Wayne Lee
Mary Lou Smith
John G. Sled
Margot J. Taylor

We evaluated whether the volume and growth rate of critical brain structures measured by MRI in the first weeks of life following very preterm (<32/40weeks) birth could predict subsequent neurodevelopmental outcomes at 4years of age. A significant proportion of children born very prematurely have cognitive deficits, but these problems are often only detected at early school age. Structural T2-weighted magnetic resonance images were acquired in 96 very preterm neonates scanned within 2weeks of birth and 70 of these at term-equivalent age. An automated 3D image analysis procedure was used to measure the volume of selected brain structures across all scans and time points. At 4years of age, 53 children returned for neuropsychological assessments evaluating IQ, language and visual motor integration. Associations with maternal education and perinatal measures were also explored. Multiple regression analyses revealed that growth of the caudate and globus pallidus between preterm birth and term-equivalent age predicted visual motor integration scores after controlling for sex and gestational age. Further associations were found between caudate and putamen growth with IQ and language scores. Analyses at either preterm or term-equivalent age only found associations between normalized deep grey matter growth and visual motor integration scores at term-equivalent age. Maternal education levels were associated with measures of IQ and language, but not visual motor integration. Thalamic growth was additionally linked with perinatal measures and presence of white matter lesions. These results highlight deep grey matter growth rates as promising biomarkers of long-term outcomes following very preterm birth, and contribute to our understanding of the brain–behaviour relations in these children.

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YNICL Journal 2015 Journal Article

Early neural activation during facial affect processing in adolescents with Autism Spectrum Disorder

Rachel C. Leung
Elizabeth W. Pang
Daniel Cassel
Jessica A. Brian
Mary Lou Smith
Margot J. Taylor

Impaired social interaction is one of the hallmarks of Autism Spectrum Disorder (ASD). Emotional faces are arguably the most critical visual social stimuli and the ability to perceive, recognize, and interpret emotions is central to social interaction and communication, and subsequently healthy social development. However, our understanding of the neural and cognitive mechanisms underlying emotional face processing in adolescents with ASD is limited. We recruited 48 adolescents, 24 with high functioning ASD and 24 typically developing controls. Participants completed an implicit emotional face processing task in the MEG. We examined spatiotemporal differences in neural activation between the groups during implicit angry and happy face processing. While there were no differences in response latencies between groups across emotions, adolescents with ASD had lower accuracy on the implicit emotional face processing task when the trials included angry faces. MEG data showed atypical neural activity in adolescents with ASD during angry and happy face processing, which included atypical activity in the insula, anterior and posterior cingulate and temporal and orbitofrontal regions. Our findings demonstrate differences in neural activity during happy and angry face processing between adolescents with and without ASD. These differences in activation in social cognitive regions may index the difficulties in face processing and in comprehension of social reward and punishment in the ASD group. Thus, our results suggest that atypical neural activation contributes to impaired affect processing, and thus social cognition, in adolescents with ASD.

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YNIMG Journal 2012 Journal Article

Development of ACC–amygdala activations in processing unattended fear

Yuwen Hung
Mary Lou Smith
Margot J. Taylor

The ability to assess facial expressions of others involves specialised brain systems important for emotional and social learning, a skill that emerges over childhood. We investigated the development of neural responses associated with implicit processing of facial emotions using magnetoencephalography in children (7–10yrs), adolescents (12–15yrs) and adults. The results demonstrated spatial–temporal activations in the ACC and amygdala emotion-processing systems that changed with age. The processing of emotions first engaged the earlier-developing amygdala responses and then involved the later-maturing ACC system. With increasing age there was a shift in lateralization of amygdala responses sensitive to the fearful faces. The findings contribute to a critical understanding of the development related to functional specialization of fear perception in the frontal–limbic emotion systems. The present study offers critical insights into the developmentally time-sensitive impact on the normal functioning of these brain regions.

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YNIMG Journal 2010 Journal Article

Unattended emotional faces elicit early lateralized amygdala–frontal and fusiform activations

Yuwen Hung
Mary Lou Smith
Dimitri J. Bayle
Travis Mills
Douglas Cheyne
Margot J. Taylor

Human adaptive behaviour to potential threats involves specialized brain responses allowing rapid and reflexive processing of the sensory input and a more directed processing for later evaluation of the nature of the threat. The amygdalae are known to play a key role in emotion processing. It is suggested that the amygdalae process threat-related information through a fast subcortical route and slower cortical feedback. Evidence from human data supporting this hypothesis is lacking. The present study investigated event-related neural responses during processing of facial emotions in the unattended hemifield using magnetoencephalography (MEG) and found activations of the amygdala and anterior cingulate cortex to fear as early as 100 ms. The right amygdala exhibited temporally dissociated activations to input from different visual fields, suggesting early subcortical versus later cortical processing of fear. We also observed asymmetrical fusiform activity related to lateralized feed-forward processing of the faces in the visual–ventral stream. Results demonstrate fast, automatic, and parallel processing of unattended emotional faces, providing important insights into the specific and dissociated neural pathways in emotion and face perception.

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