A PHONOLOGICAL ANALYSIS OF A DEAF PARKINSONIAN SIGNER

The study of deaf signers with distinct motor disorders can provide cl ues to the neural substrate underlying language as motor behaviour. Mo reover, since the structure of intended limb movement targets can be s o clearly specified in sign language, such studies provide as well an important new vehicle for illuminating the functional properties of th e motor systems of the brain. This investigation brings to bear recent theoretical models of phonological representation of American Sign La nguage (ASL) on an analysis of the signing deficits of a deaf signer w ith Parkinson's disease. We provide a detailed analysis of this subjec t's particular profile of phonological and phonetic disturbances in AS L in order to (1) clarify the fine motor disruptions of the limbs duri ng the production of sign language caused by Parkinson's disease, and (2) refine models of ASL phonology. The disturbances in the subject's signing can be characterised by reductions and timing disruptions that include distalisation of movement, prolonged handshape changes and a lowered default signing space. By relating the signing of both the con trol and Parkinsonian subjects to a syllable template, we conclude tha t the signing disturbances of the Parkinsonian signer are in the domai n of phonetic execution rather than in the phonological grammar itself .