Based on research of word processing and verbal STM impairments in aphasia, it has been proposed that the co-occurrence of these impairments is due to a disruption of cognitive processes that support both abilities: maintenance of activated semantic and phonological representations of words, hereafter the 'activation--maintenance hypothesis'.~This hypothesis will be tested in the context of a treatment approach that aims to improve word processing and verbal STM abilities. Recently, the importance of treatment research has been emphasized as a critical testing ground for theories of language processing. Although it has been demonstrated that associations between impairments of word processing and reduced verbal STM capacity support the 'activation-maintenance hypothesis', direct treatments to improve the ability to maintain activation of word representations will serve as a stronger test of this hypothesis. First, empirical support will be established for the hypothesis that impairment to short-term maintenance of activated semantic and phonological representations of words impairs language and verbal STM abilities in aphasia and that direct treatment of this deficit will improve both abilities (Specific Aim 1). Second, the effects of this treatment will be compared under two administration conditions, high and low intensity (Specific aim 2). Finally, the neural regions associated with semantic STM and phonological STM will be investigated using voxel--based lesion--symptom mapping (Bates et al., 2003) (Specific Aim 3).~This research represents a unique attempt to apply more recent processing theories of aphasia to treatment of the disorder.The outcomes will have important implications for aphasia rehabilitation research.
The aim of this research is to translate a theory of the cognitive relationship between verbal short--term memory (STM) and word processing impairments in aphasia to treatment approaches for language impairment in aphasia. It has been proposed that the co-occurrence of these impairments is due to a disruption of cognitive processes that support both abilities: maintenance of activated semantic and phonological representations of words, hereafter the 'activation--maintenance hypothesis'.~This hypothesis will be tested in the context of a treatment approach that aims to improve word processing and verbal STM abilities.