A selective deficit in the production of exact musical intervals following right-hemisphere damage

In this study we focused our attention on the production of music in its vocal form. To our knowledge this is the first detailed description of a dissociation between encoding and retrieval of melodic intervals in music. We describe the case of a 55-year-old high-level amateur musician, IP, who had suffered a right-hemisphere stroke. While the patient performs well in music recognition and discrimination tasks, he is selectively impaired at singing correct intervals. More precisely, IP's performance relative to the rhythm and the contour retrieval of musical patterns is preserved; his impairment is limited to precise pitch retrieval and it is highly correlated to the degree of dissonance of the intervals he is required to sing. These findings are discussed relative to previous works in neuropsychology of music with regard to both functional models and brain function localisation. An extended version of the model proposed by Peretz (1993b) is presented.