‌Brain activation to spoken sentences in aphasia: Effects of electrical brain stimulation

Overview

Our research has suggested that people with comprehension problems following stroke often retain information about the meanings of words and objects, but have difficulty regulating the retrieval of such information. In this project, we will use brain imaging to improve our understanding of these problems. Participants will listen to sentences containing ambiguous words (i.e., words like “bank” which contain multiple and conflicting meanings) in the scanner. We will contrast these sentences with easier ones (without ambiguity) and with meaningless noise.

Healthy participants show brain activity in two regions – within left frontal and temporal cortex – in response to ambiguous sentences. These brain areas are damaged following stroke. This project will explore (i) the brain areas that still respond to meaningful sentences in each patient, including how the brain compensates for damage; (ii) which areas of increased and decreased brain activity (compared to healthy aged-matched controls) are associated with good and poor comprehension in tests outside the scanner; (iii) how this pattern of brain activity is altered by the application of electrical stimulation (to brain areas surrounding the stroke damage). This might lead to better ways of delivering and evaluating electrical stimulation as a method for neurorehabilitation.

Preliminary results show strong activity for meaningful sentences relative to meaningless noise in left anterior temporal lobe as well as perilesional areas in left prefrontal cortex. Thus the imaging is providing us with potential sites in ongoing tDCS studies of aphasia rehabilitation.