Impairments in Complex Language and Coverbal Gestures Idiopathic Parkinson Disease

S Duncan, A Galati, W Goodrich, L Ramig, M Brandabur

 

People produce meaningful bodily and facial movements when speaking. Gesture, facial affect, and speech prosody are linked and integral aspects of complex language production. They illuminate the production process at several levels of discourse analysis; e.g., they: reveal speaker thoughts and discourse plan when speech content is uninformative or ambiguous, illuminate semantic continuity between utterances, help to establish and maintain discourse themes, and punctuate points of contrastive discourse focus. Further, as persisting embodied representations, gestures support working memory, aiding the construction of coherent discourse. Given their communicative and cognitive significance, it is important to study these behaviors in individuals with Idiopathic Parkinson Disease, a neuromotor disorder that affects control of a range of bodily movements, and has known effects on articulation, voice, prosody, and expression of affect. We document impaired discourse structure and paucity of discourse content in 18 individuals with moderately severe IPD, who were videotaped telling a story. Deficiencies in complex language use correlate with lower rates of gesture production and low-specificity of gesture forms, compared to normals; also, with confusions seemingly brought on by aberrant timing relationships between hesitantly-produced gestures and co-expressive speech.