Treating Intention in Aphasia: Neuroplastic Substrates

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DESCRIPTION (provided by applicant): A new treatment manipulating intention substrates for language production in "nonfluent" aphasia patients was developed. The intention component involves initiating word-finding trials with a complex left-hand movement. In a preliminary study, the rate of change in naming accuracy was faster for this treatment than for a similar treatment without the intention component. However, the assumption that the treatment evokes a shift of language production functions from the left to the right frontal lobe has been tested only in a small number of patients (N = 5) whose lateralization was variable before treatment, and appropriate stringent control procedures to verify that the shift in lateralization was due to the intention component were not used. The proposed study will address the hypothesized shift in lateralization in a larger sample of "nonfluent" aphasia patients and with an appropriate control group. In a parallel group design, 13 patients will receive the intention treatment and 13 patients will receive a control treatment that is identical to the intention except that the intention component is absent. All subjects will participate in functional magnetic resonance imaging (fMRI) scans of word-finding before and after treatment to measure changes in lateralization of lateral frontal and pre-SMA activity. Only patients with a substantial degree of left frontal activity on the pre-treatment scan will participate. The long-term objective is to determine if the intention treatment produces the hypothesized rightward shift in lateral frontal and pre-SMA activity. There are three specific aims: (1) to determine if repetitive initiation of word production with a complex left-hand movement leads to increased right- hemisphere lateralization of pre-SMA and lateral frontal activity and if these changes can be attributed to the intention component of treatment, (2) to determine whether activity in posterior perisylvian cortices that is entrained to right frontal activity shows a greater increase in right-hemisphere lateralization for the intention than for the control group from pre- to post-treatment fMRI, and (3) to determine whether onset of hemodynamic responses (HDRs) in right motor/premotor cortex becomes more closely associated with the temporal onset of participants' spoken responses across treatment for the intention vs the control treatment. The proposed study has the following potential benefits: First, if successful, the treatment can provide a new treatment vehicle for increasing language function and reducing suffering in patients with "nonfluent" aphasia. Second, the treatment can produce a paradigm shift in the development of aphasia treatment by emphasizing mechanisms for producing desirable changes in the brain mechanisms for language production and by verifying the target changes with fMRI.