Research in the lab is focused on three related questions:
- How is language processed in the brain?
- How does brain damage affect language processing in individuals with aphasia, i.e. acquired language disorders?
- What brain mechanisms support the recovery of language processing in people with aphasia who improve over time?
To address these questions, we study individuals with aphasia, as well as healthy participants with normal language, using a range of state-of-the-art neuroimaging techniques including functional magnetic resonance imaging, diffusion tensor imaging and perfusion imaging. We combine our multimodal imaging approach with comprehensive language assessments designed to quantify deficits in different components of the language processing system, such as syntactic structures, word meanings, or the selection and assembly of speech sounds.
|Functional MRI||Diffusion tensor imaging||DTI Tractography||DSC Perfusion||ASL Perfusion|
Recovery from aphasia after stroke
Aphasia is one of the most common and debilitating consequences of strokes affecting the dominant hemisphere. In the first few months after a stroke, most patients experience some degree of spontaneous recovery of language function. These first few months after brain damage occurs are critically important because the greatest behavioral gains take place during this time, even when patients do not receive treatment. However the extent of recovery is highly variable: some patients recover most or nearly all language function, while others make few gains and remain chronically aphasic. It is not well understood what neural mechanisms underlie recovery during this period, nor why some patients recover so much better than others.
In one major project in the lab, we are studying individuals with aphasia in the first three months after they experience a stroke. Our aims are to identify the neural changes that are associated with successful recovery from aphasia in this period, and to determine what factors are most predictive of the extent and time course of eventual recovery from aphasia. A better understanding of the neural correlates of successful recovery will improve the accuracy of prognoses so as to better plan medical treatments and behavioral interventions.
This project is supported by a grant from the NIH (National Institute on Deafness and Other Communication Disorders, R01 DC013270, 2014-2019).
|2 days post (Left)||2 days post (Right)||2 weeks post (Left)||2 weeks post (Right)||6 weeks post (Left)||6 weeks post (Right)|
When we think of cognitive deficits due to age-related brain diseases, we usually think first of the memory loss associated with the most common neurodegenerative disease: Alzheimer's disease. However, Alzheimer's disease is not the only neurodegenerative disease, and different neurodegenerative diseases can affect different brain regions, including left hemisphere brain regions that are important for language. Degeneration of these regions leads to language impairments, and when aphasia is the first and most prominent symptom of neurodegeneration, this is termed primary progressive aphasia.
In a second major research project in the lab, we are using multiple neuroimaging methodologies to investigate neural changes underlying language deficits in primary progressive aphasia. The knowledge gained in this study will increase our understanding of the neural basis of language processing and its breakdown in primary progressive aphasia, and will contribute to earlier, more accurate differential diagnosis of different types of primary progressive aphasia, enabling emerging pharmaceutical interventions to be targeted to likely underlying causes.
This project was supported by a grant from the NIH (National Institute on Deafness and Other Communication Disorders, R03 DC010878, 2010-2013).
Maximizing the anatomical precision of functional MRI
Functional MRI (fMRI) is the most widely used technique for exploring the role of different cortical regions in various cognitive, linguistic, affective and social processes. The anatomical precision of fMRI is limited not only by the spatial resolution of the images themselves, but also by the anatomy of the vascular network, since fMRI measures neural activity indirectly via its effects on changes in blood oxygenation. We are investigating methods for taking vascular anatomy into account when interpreting fMRI images. This is important when studying individuals such as patients with post-stroke aphasia, whose vascular anatomy may not be normal.