Current PhD Students
Kaori (Lily) Ito
Kaori (Lily) Ito
Faculty Mentor: Sook-Lei Liew PhD, OTR/L
Research Lab: Neural Plasticity and Neurorehabilitation Lab
Year of Entry: 2016
Master of Arts (MA)
in Occupational Therapy
2016 | University of Southern California
Bachelor of Arts (BS)
in Cognitive Science
2013 | University of California, Los Angeles
Stroke is a neurological disorder that can leave an individual with lasting motor impairments. Among a wide range of factors that can influence stroke recovery, hemispheric dominance relative to the stroke — that is, whether a stroke is in a person’s dominant or non-dominant hemisphere — is likely to have a significant impact on function. For example, an individual whose stroke is in the dominant hemisphere may have difficulty performing daily activities that depend on the dominant hand, such as hand-writing and teeth-brushing.
At the Neural Plasticity and Neurorehabilitation Lab, I’m interested in understanding the effects of stroke laterality on neural plasticity and its implication on stroke recovery and rehabilitation. Through the use of functional MRI, I’m studying changes in brain activity and connectivity in motor-related networks following a stroke using various statistical modeling techniques, such as GLM-weighted correlation analyses and dynamic causal modeling.
Liew, S.-L., Garrison, K. A., Ito, K. L., Heydari, P., Sobhani, M., Werner, J., Damasio, H., Winstein, C. J., & Aziz-Zadeh, L. (2018). Laterality of poststroke cortical motor activity during action observation is related to hemispheric dominance. Neural Plasticity, 2018, 3524960. https://doi.org/10.1155/2018/3524960 Show abstract
Background. Increased activity in the lesioned hemisphere has been related to improved poststroke motor recovery. However, the role of the dominant hemisphere—and its relationship to activity in the lesioned hemisphere—has not been widely explored.
Objective. Here, we examined whether the dominant hemisphere drives the lateralization of brain activity after stroke and whether this changes based on if the lesioned hemisphere is the dominant hemisphere or not.
Methods. We used fMRI to compare cortical motor activity in the action observation network (AON), motor-related regions that are active both during the observation and execution of an action, in 36 left hemisphere dominant individuals. Twelve individuals had nondominant, right hemisphere stroke, twelve had dominant, left-hemisphere stroke, and twelve were healthy age-matched controls. We previously found that individuals with left dominant stroke show greater ipsilesional activity during action observation. Here, we examined if individuals with nondominant, right hemisphere stroke also showed greater lateralized activity in the ipsilesional, right hemisphere or in the dominant, left hemisphere and compared these results with those of individuals with dominant, left hemisphere stroke.
Results. We found that individuals with right hemisphere stroke showed greater activity in the dominant, left hemisphere, rather than the ipsilesional, right hemisphere. This left-lateralized pattern matched that of individuals with left, dominant hemisphere stroke, and both stroke groups differed from the age-matched control group.
Conclusions. These findings suggest that action observation is lateralized to the dominant, rather than ipsilesional, hemisphere, which may reflect an interaction between the lesioned hemisphere and the dominant hemisphere in driving lateralization of brain activity after stroke. Hemispheric dominance and laterality should be carefully considered when characterizing poststroke neural activity.
Liew, S.-L., Anglin, J. M., Banks, N. W., Sondag, M., Ito, K. L., Kim, H., Chan, J., Ito, J., Jung, C., Khoshab, N., Lefebvre, S., Nakamura, W., Saldana, D., Schmiesing, A., Tran, C., Vo, D., Ard, T., Heydari, P., Kim, B., Aziz-Zadeh, L., Cramer, S. C., Liu, J., Soekadar, S., Nordvik, J.-E., Westlye, L. T., Wang, J., Winstein, C., Yu, C., Ai, L., Koo, B., Craddock, R. C., Milham, M., Lakich, M., Pienta, A., & Stroud, A. (2018). A large, open source dataset of stroke anatomical brain images and manual lesion segmentations. Scientific Data, 5, 180011. https://doi.org/10.1038/sdata.2018.11 Show abstract
Stroke is the leading cause of adult disability worldwide, with up to two-thirds of individuals experiencing long-term disabilities. Large-scale neuroimaging studies have shown promise in identifying robust biomarkers (e.g., measures of brain structure) of long-term stroke recovery following rehabilitation. However, analyzing large rehabilitation-related datasets is problematic due to barriers in accurate stroke lesion segmentation. Manually-traced lesions are currently the gold standard for lesion segmentation on T1-weighted MRIs, but are labor intensive and require anatomical expertise. While algorithms have been developed to automate this process, the results often lack accuracy. Newer algorithms that employ machine-learning techniques are promising, yet these require large training datasets to optimize performance. Here we present ATLAS (Anatomical Tracings of Lesions After Stroke), an open-source dataset of 304 T1-weighted MRIs with manually segmented lesions and metadata. This large, diverse dataset can be used to train and test lesion segmentation algorithms and provides a standardized dataset for comparing the performance of different segmentation methods. We hope ATLAS release 1.1 will be a useful resource to assess and improve the accuracy of current lesion segmentation methods.