Investigating insight into inner speech in aphasia



 DESCRIPTION (provided by applicant): Aphasia, an acquired impairment of language and communication, affects about one million Americans, and causes significant long-term disability. People with aphasia often feel that they can say certain words in their heads, even though they can't say them aloud. Because this sense of "successful inner speech" is hard to verify, clinicians cannot be sure whether these reports are meaningful, and if so, what they can tell us about the internal mental processes of word-finding. Remarkably, although the sense of successful inner speech is an everyday experience for many people with aphasia, only one prior study, published in 1976, directly asked people with aphasia about their inner speech and tested whether these self-reports are meaningful. Building on this prior work using modern techniques, this project examines how subjective reports of inner speech relate to objective measures of the psychological and neural processes of word-finding. The main hypothesis is that the sense of successful inner speech emerges from access to a phonological word form. A corollary of the hypothesis is that brain activity related to phonological access corresponds with the subjective report of whether inner speech is correct or not. We will test these hypotheses using an inner/aloud naming task, phonological judgments, and functional MRI of inner naming. These tests examine whether reports of inner speech predict (1) subsequent aloud speech, (2) access to phonological information about the same words, and (3) brain activity when calling these words to mind. The study is designed to test hypotheses at the single-subject level because individual differences in language and cognitive deficits are expected to influence insight into inner speech. Pilot data collected to date demonstrate that self-reports of inner speech in aphasia are meaningful and likely reflect phonological access as hypothesized. We have also found that self-reports of inner speech predict word-by-word success in subsequent anomia treatment, demonstrating the clinical importance of this work. This research will provide a new source of information to study language and aphasia, and potentially a new way to guide individualized aphasia therapy. Further, this research will improve our understanding of the personal experience of having aphasia, an important goal for clinicians, people with aphasia, and their families.