One focus of research in aphasia therapy has been to understand how the content of treatment interacts with impaired word representations (Nettleton &Lesser, 1992) and whether therapy is more effective if its content directly stimulates impaired representations (e.g., semantic therapy for semantic impairments). This focus is important, but does not address the dynamic processes of word retrieval. We propose to investigate an approach to treatment of aphasia that targets the processes by which semantic and phonological representations of words are activated and maintained during comprehension and production of language. This focus is timely, as these activation processes have been described and tested as accounts of aphasic impairment in models of word processing (e.g., Dell, Schwartz, Martin, Saffran &Gagnon, 1997) and verbal short-term memory (STM) deficits in aphasia (Martin &Gupta, 2004). Moreover, recent studies of treatments for auditory-verbal STM deficits in aphasia have invoked these theoretical models as a framework for linking STM deficits with comprehension and production deficits in aphasia (Majerus, van der Kaa, Renard, Vander Linden &Poncelet, 2005). Thus, following models that connect the two deficits by way of the dynamics of activation processes (Martin &Saffran, 1997), we will extend this connection to treatment that focuses on improving the ability to maintain activation of word representations. The project includes two parts. First, we will obtain normative data from aphasic and nonaphasic individuals on a diagnostic battery that assesses the ability to activate and maintain activation of semantic and phonological representations of single and multiple word utterances. Second, we will test the efficacy of a treatment program to improve the ability to activate and maintain activation of semantic and/or phonological representations of single word and multiple word utterances in short-term memory. The efficacy of the treatment will be examined with probes of acquisition and maintenance in a multiple baseline across multiple stimuli design, and with comparisons of pre- and post-test performance on the diagnostic battery and the treatment tasks. This research should have significant benefit to public health. Although language impairments following stroke are often a life-long disability, treatments based on a comprehensive understanding of the language system and its breakdown following brain damage have led to improved language function, even in chronic stages of this disability. This project will examine the efficacy of a diagnostic battery and treatment program for word processing and short-term memory impairments, which invariably co-occur in aphasia. The unique aspect of this program is that it examines and treats word processing deficits in contexts that gradually increase the stress on working memory, thus approximating more closely the conditions in which functional communication occurs. This research should have significant benefit to public health. Although language impairments following stroke are often a life-long disability, treatments based on a comprehensive understanding of the language system and its breakdown following brain damage have led to improved language function, even in chronic stages of this disability.
