Prosody Assessment After Right Hemisphere Stroke

Overview

Following a right stroke, more than half of the patients present a communication disorder. These disorders can notably concern prosody. Nevertheless, these remain relatively poorly assessed and characterized. Prosodic alterations in comprehension can result in a disruption of social cognition with potentially important consequences in terms of functional outcome and quality of life of patients. In clinical practice, the investigators do not have a tool that allows us to finely assess these disorders. Studies in healthy subjects using a processing algorithm capable of arbitrarily manipulating the pitch dynamics of recorded voices have revealed that there are stable internal representations for prosody processing. Initial pilot results show that this method can be used in a clinical context and can indeed identify and accurately measure perceptual processing deficits in prosody following a right stroke. It is necessary to continue the study of this approach with a larger number of subjects in order to have normative data and validate the diagnostic properties of this approach.

The aim of this project is to study impairments of speech prosodic perception using a novel data-driven psychoacoustic technique, reverse correlation. The project will, first, conduct a prospective diagnostic study on N=150 stroke patients and controls, in order to evaluate the relevance of reverse-correlation data as a marker of prosodic impairments. Second, the project will use this novel patient data for theoretical investigations such as lesion-symptom mapping, in order to better understand how prosodic processing differs between patients and controls. Finally, the project will develop a novel mobile audio-health platform to facilitate the adoption of the reverse-correlation procedure in clinical practice and to collect remote patient data to assist medical decision-making. The rationale of the reverse correlation technique is to uncover a listener's mental representation of certain prosodic patterns (e.g. the different intonation of "really?" vs "really!") by analyzing a large set of responses to random stimuli. The expected results of the project are threefold: (1) the investigators will provide a new tool able to diagnose stroke-related prosody impairments beyond existing gold standards, (2) the investigators will provide a finer characterization of symptomatological profiles in these patients and (3) the investigators will provide a new prognosis metric, implemented in a mobile application, to quantify how well a patient reacts to speech therapy day after day. The project will both further our understanding of aprosodia and provide new clinical tools to improve its diagnosis and rehabilitation. Beyond stroke, the project will also provide a case-study for the application of reverse-correlation to general speech therapy practice, benefiting patients across the whole spectrum of hearing impairments.