For the past decade, our laboratory has been studying cognitive deficits associated with right hemisphere stroke, including deficits due to dysfunctional (hypoperfused) tissue, and how to bring about improvements in function by restoring blood flow. This project initially led to some novel insights regarding brain regions essential for spatial attention (and lesions that cause different types of hemispatial neglect), as well as novel interventions for to improve cognitive function in acute stroke. During this project, we noted the frequency and importance of other deficits frequently associated hemispatial neglect, such as loss of empathy and emotional expression in individuals with right hemisphere stroke. These deficits have an enormous impact on the dignity of the individuals and on their relationships with caregivers.
Along with hemispatial neglect, deficits in emotional empathy and affective prosody are among the most common and disabling consequences of right hemisphere stroke. We are now focused on characterizing the nature and neural correlates of impairments in empathy and affective prosody (understanding and producing language with appropriate intonation, rate, pauses, and stress to convey emotion), and their association with hemispatial neglect.
We are combining our unique methodology of studying the neural bases of cognitive functions (evaluating changes in blood flow with concurrent changes in task performance) with resting state functional connectivity MRI (rsfcMRI) to investigate the neurobiology of recovery of spatial attention, empathy, and prosody, over the first year after stroke. We believe that by combining careful analysis of the changes in cerebral blood flow with changes in resting state connectivity (measured by correlations in the hemodynamic response in various areas at rest), and changes in anatomical connectivity, we will develop a better understanding of recovery of some important cognitive functions over the first year after right hemisphere stroke. We will determine the relative contributions of neural and demographic variables to predicting and accounting for recovery from neglect and impairments of empathy and prosody. Insights into recovery of such complex cognitive functions will require an understanding of changes in networks revealed by rsfcMRI, and identifying the influence of many variables, such as percent damage to specific white matter tracts, location and volume of dysfunctional tissue, age, and baseline performance.
This research will contribute to understanding and predicting if, how, and when people who have had right hemisphere stroke will recover spatial attention as well as the ability to recognize and respond to emotions of others and the ability to understand and express emotions through tone of voice. A better understanding of how these functions recover over the first year after stroke is essential, because of the impact of these deficits on the interpersonal relationships of stroke survivors. The results will also have clinical impact by aiding in functional prognosis in acute stroke, and will provide a basis for neurally-targetted treatments for cognitive deficits after right hemisphere stroke.
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