Crosslinguistic/crossmodal syntactic consequences of left-hemisphere damage: Evidence from an aphasic signer and his identical twin

Abstract

This paper presents the first theoretically driven syntactic analysis of the narrative production of a left-lesioned Deaf signer with aphasia. In addition to a more traditional neuropsychological work-up, specialized studies of movement abilities and linguistic capacities were performed. Three-dimensional motion analyses were performed on left-lesioned N.S.'s production of non-linguistic gesture, revealing intact praxis. Signed narratives elicited via non-verbal cartoons were coded with respect to a variety of grammatical characteristics: argument structure instantiated in each clause, use of aspectual morphology, and the morphological agreement class of each verb (plain, person agreeing, or locative). This information was used to construct a syntactic profile for N.S. that could be compared to a parallel profile constructed for his identical twin control. Analysis not only of manual, but also non-manual components of signed sentences revealed a focused deficit in sentence-level, non-lexically linked, grammatical facial expressions co-occurring with spared abilities in the perception and production of facial affect as well as face recognition. Breakdown of grammatical use of face and space in ASL is shown to provide sources of both crosslinguistic and crossmodal evidence that make a unique contribution to the delineation of universal aspects of language representation in the brain.