Differences in linguistic cohesion within the first year following right- and left-hemisphere lesions

Background: Characterizing productive language deficits following lesions to the right (RH) or left hemispheres (LH) is valuable in identifying appropriate therapeutic goals. While damage to the LH classically is associated with deficits in language, RH lesions also result in changed communication beyond prosody due to cognitive-linguistic effects. Cohesion, reference to introduced content across sentences within discourse, relies on a listener’s clear and unambiguous understanding that a reference has occurred. To date, we are not aware of any prior work that has compared patterns of cohesive strategy between RH and LH lesioned individuals with cohesion deficits. Aims: The purpose of the present study is to determine whether individuals with communication deficits following RH and LH lesions differ in the inclusion and clarity of cohesive markers. Methods & Procedures: Seventy-six RH samples and 145 LH samples were used for comparison of cohesion performance in a Cookie Theft picture description task. It was hypothesized that individuals with LH lesions would present a different pattern of cohesion behaviour than RH lesioned individuals when considered both acutely and chronically. Outcomes & Results: Overall, samples from LH and RH groups did not differ in word counts or cohesive marker usage. However, the patterns of markers they chose to employ were different. LH samples used conjunctions and personal pronouns more frequently and used lexical cohesive markers less frequently than RH samples. Acutely, patterns of cohesive marker use between LH and RH samples were more similar. Chronically, LH samples contained more personal pronouns and the differences in lexical cohesive markers remained unchanged. When cohesion was unsuccessful, LH and RH damage were associated with different patterns of error. LH samples tended to omit information needed to clarify the intended referent, resulting in incomplete cohesion errors. RH samples tended to sustain breakdowns in cohesion from sentence to sentence, not resolving incorrectly chosen pronouns or ambiguities left in their samples. Conclusions: LH and RH lesions resulted in differing patterns of chosen cohesive markers and errors when cohesion was unsuccessful. This was particularly true in lexical cohesion, which has been far less studied than closed-class cohesive markers like referential pronouns. It was also noted that cohesive behavior did not appear to “recover” for either group, suggesting the spontaneous recovery is minimal and present strategies for language therapy may not effectively address this linguistic function.