Treating agrammatic aphasia within a linguistic framework: Treatment of Underlying Forms

Background: Formal linguistic properties of sentences-both lexical, i.e., argument structure, and syntactic, i.e., movement - as well as what is known about normal and disordered sentence processing and production, were considered in the development of Treatment of Underlying Forms (TUF), a linguistic approach to treatment of sentence deficits in patients with agrammatic aphasia. TUF is focused on complex, non-canonical sentence structures and operates on the premise that training underlying, abstract, properties of language will allow for effective generalisation to untrained structures that share similar linguistic properties, particularly those of lesser complexity. Aims: In this paper we summarise a series of studies focused on examining the effects of TUF. Methods & procedures: In each study, sentences selected for treatment and for generalisation analysis were controlled for their lexical and syntactic properties, with some structures related and others unrelated along theoretical lines. We use single-subject experimental designs - i.e., multiple baseline designs across participants and behaviours - to chart improvement in comprehension and production of both trained and untrained structures. One structure was trained at a time, while untrained sentences were tested for generalisation. Participants included individuals with mild to moderately severe agrammatic, Broca's aphasia with characteristic deficits patterns. Outcomes & results: Results of this work have shown that treatment improves the sentence types entered into treatment, that generalisation occurs to sentences which are linguistically related to those trained, and that treatment results in changes in spontaneous discourse in most patients. Further, we have found that generalisation is enhanced when the direction of treatment is from more to less complex structures, a finding that led to the Complexity Account of Treatment Efficacy (CATE, Thompson, Shapiro, Kiran, & Sobecks, 2003). Finally, results of recent work showing that treatment appears to affect processing of trained sentences in real time and that treatment gains can be mapped onto the brain using functional magnetic resonance imaging (fMRI) are discussed. Conclusions: These findings indicate that TUF is effective for treating sentence comprehension and production in patients who present with language deficit patterns like those seen in our patients. Patients receiving this treatment show strong generalisation effects to untrained language material. Given the current healthcare climate, which limits the amount of treatment that aphasic patients receive following stroke, it is important that clinicians deliver treatment that results in optimal generalisation in the least amount of time possible.