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Defining the Neurobiological Mechanisms of Action in Aphasia Therapies: Applying the Rehabilitation Treatment Specification System Framework to Research and Practice in Aphasia

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Abstract

The Rehabilitation Treatment Specification System (RTSS) was developed as a systematic way to describe rehabilitation treatments for the purpose of both research and practice. The RTSS groups treatments by type and describes them by 3 elements: the treatment (1) ingredients and (2) the mechanisms of action that yield changes in the (3) target behavior. Adopting the RTSS has the potential to improve consistency in research, allowing for better cross-study comparisons to strengthen the body of research supporting various treatments. Because it is still early in its development, the RTSS has not yet been widely implemented across different rehabilitation disciplines. In particular, aphasia recovery is one area of rehabilitation that could benefit from a unifying framework. Accordingly, this article is part of a series where we illustrate how the RTSS can be applied to aphasia treatment and research. This article more specifically focuses on examining the neurobiological mechanisms of action associated with experimental aphasia therapies, including brain stimulation and pharmacologic intervention, as well as more traditional behavioral therapy. Key elements of the RTSS are described, and 4 example studies are used to illustrate how the RTSS can be implemented. The benefits of a unifying framework for the future of aphasia treatment research and practice are discussed.

Section snippets

Rehabilitation Treatment Specification System

As previewed earlier, the RTSS is a framework for defining the elements of a treatment that lead to change(s) in the target behavior. To this end, the RTSS structures treatments so that ingredients (ie, what the clinician does) exert a measurable change on the target skill, via some MOA.3, 4, 5 In turn, the accomplishment of multiple targets leads toward an overall aim, or long-term goal of the treatment. Generally, an aim cannot be met by the improvement of a single skill. If that is the case,

Noninvasive brain stimulation

Thiel10 and Meinzer11 and colleagues used noninvasive brain stimulation to improve language by affecting specific neural mechanisms. Like the other studies reviewed in this article, these 2 studies are examples of organ function treatments. The key ingredients are related to the brain stimulation applied; one method downregulated activity in the right hemisphere to boost left hemisphere activity (Thiel10), and another directly stimulated the stroke-affected left hemisphere (Meinzer11).

First,

Pharmacologic intervention

Pharmacologic interventions have been investigated to modulate brain function. Pharmacologic intervention is another approach that falls within the organ function treatment group and can either be paired with traditional speech-language therapy or used as part of a “drug only” approach to improving aphasia.24 In an example study, Berthier et al15 investigated the effects of a daily dose of 10 mg of memantine on aphasia recovery in 14 participants compared with 13 participants taking a placebo.

Behavioral therapy with explicit neurobiological mechanisms

The last studies we discuss are those that aimed to use behavioral therapy to target language improvements via neural reorganization. These studies are by Abel16,17 and Wilson18 and colleagues. For both studies, treatment ingredients are behavioral speech and language therapies, and targets are language behaviors supported by specific neural processes. Proposed MOAs that improve target behaviors are explained by up and down regulation of key brain regions involved in language,16 promoting more

Discussion

The studies reviewed above illustrate how aphasia therapies can be described using the RTSS framework. Given its emphasis on understanding how treatments work and why, if we frame the aphasia treatment literature according to the RTSS, then we can collate studies to gather evidence supporting how different ingredients influence various neural mechanisms, developing support for theories of the neurobiology of aphasia recovery based on results across multiple studies (and therefore, larger sample

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    Disclosures: none

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