Theory-Driven Treatment of Language and Cognitive Processes in Aphasia

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.

Experimental participants:

Inclusion Criteria:

- Aphasia

- Single left hemisphere lesions

- Right handed

- At least six months post-stroke

- Aged 21 to 80

- High-school educated with English as their primary language

- Passed an audiometric pure tone, air conduction screening at 25 dB HL at 1K, 2K and 4K
Hz for at least one ear (with or without correction)

- Demonstrate adequate vision with or without correction.

- Will not exclude individuals with a mild apraxia of speech or mild dysarthria of
speech.

Exclusion Criteria:

- History of mental illness

- Alcohol/substance abuse

- Pregnant

- Unable to personally give informed consent

Control participants:

Inclusion Criteria:

- Aged 21 to 80

- High school educated or above

- Pass an audiometric pure tone, air conduction screening at 25 dB HL at 1K, 2K and 4K
Hz for at least one ear.

Exclusion Criteria:

- History of neurological disease or language disability

- Histories for mental illness

- Alcohol/substance abuse.