Recovery of language and theory of mind after stroke

Project Summary Left and right hemisphere (RH) strokes occur at similar frequencies and both are associated with life-altering communication deficits. However, patients with RH stroke rarely receive speech-language intervention, likely because they do not present with obvious language deficits like aphasia. Instead, they have difficulties engaging in typical

conversations which require understanding what a speaker means, especially when in opposition to what was actually

said, such as occurs in sarcasm, humor and metaphors. A specific deficit in the ability to understand others’ perspectives and intended meanings, known as theory of mind (ToM) may be a primary cause of communication deficits and a critical component of differential recovery after RH stroke. Inappropriately responding during conversation due to

misunderstandings of what a speaker knows and intends creates poor social interactions and negatively impacts relationships. For those living with RH stroke, communication deficits have profoundly damaging effects on quality of life. Our central hypothesis is that RH stroke causes discourse-level language deficits due to damage to brain areas

critical to ToM, an essential component of social communication. Our goal is to assess language and ToM abilities from acute to chronic stages of RH stroke while collecting neuroanatomical and quality of life data. We will measure the contribution of other social deficits including the processing of emotional prosody and non-verbal cues (e.g., facial

expressions) as well as cognitive deficits including working memory, executive function, and attention. To date, estimates of language and ToM deficits which occur after RH stroke and the relationship between them are inconsistent or unexplored. Most studies examine patients in rehabilitation settings who likely have large strokes and more severe

communication disorders, creating a bias in our knowledge about the effects of stroke. The effects of damage to RH brain regions, their connections, and how they contribute to language recovery are also unknown, limiting decisions about treatment priorities. Lastly, whether language recovery depends on ToM is unknown as there are no longitudinal

studies of communication recovery from acute RH stroke. We will address these gaps by examining individuals in a large group of acute stroke subjects, as they progress from acute to chronic stroke to evaluate the relationship between changes in language, ToM and their dependence on neural recovery. Our innovative approach combines recent

advances in neuropsychological testing and neuroimaging analysis to provide converging causal evidence to validate a ToM theory of RH stroke communication. Aim 1 tests the hypothesis that language depends on intact ToM at the acute stage of stroke before functional reorganization. Aim 2 tests the hypothesis that language depends on ToM associated

neural structures and connectivity acutely, before functional reorganization. Aim 3 examines recovery of language and

relationships with ToM and brain structure by assessing behavioral and neural changes across the first year after stroke. Successful outcomes include understanding the behavioral and neural mechanisms underlying RH deficits, their

evolution post-stroke, and their impact on quality of life. As a result, we will be able to develop better assessment and intervention tools, improving access to health care and long-term outcomes for this underserved patient population.