Adam B. Buchwald - US grants

Language production is a remarkably complex cognitive ability which requires the successful integration of multiple levels of cognitive/neural processing. Research on the mechanisms underlying language production is performed from a variety of disciplinary perspectives, including psycholinguistics, neurolinguistics, theoretical linguistics, computational linguistics, cognitive neuropsychology, and communication sciences and disorders. However, a complete understanding of language production requires situating our findings in a broader context that addresses the constraints that are placed on theories of language production by general cognitive, neural and computational processing principles. This award provides support for a special workshop session addressing cognitive, computational and neural constraints on theories of language production. The session will be part of the July 2012 meeting of the International Workshop on Language Production at New York University (NYU). The special session will consist of presentations by five leading scientists whose research on cognitive, neural and computational processes can directly constrain theories of language production. Over the past seven years, the International Workshop on Language Production has become the premier meeting focused solely on language production, and is thus the ideal venue to hold a special session of lectures and discussions addressing constraints on language production theories. This special session will inform language production researchers about state-of-the-art findings on the constraints on language production theories, which they can incorporate into their research, and will also provide opportunities to form collaborations between researchers who focus on language production with others who focus on more general cognitive, neural and computational issues.

? DESCRIPTION (provided by applicant): Stroke is a leading cause of disability in the United States, frequently leading to speech impairment that creates barriers to participation in professional, social, and family settings. While recovery can be promoted with speech treatment targeted to the specific locus of impairment, improvement remains modest and typically requires a large amount of therapy which contributes to rising health care costs. Thus, there is a need for time- and cost-efficient interventions to expedite and enhance recovery. Recent studies from related domains of stroke rehabilitation (limb motor control and language) indicate that non-invasive neurostimulation such as transcranial direct current stimulation (tDCS) may enhance treatment outcomes, but the potential for improving outcomes specifically for speech impairment has not yet been explored. The career development and research plans of the proposed project will allow the candidate to establish a T2 translational research program as an independent investigator to systematically explore the potential for tDCS to enhance treatment outcomes in individuals with stroke-induced speech impairment. The career development plan will help expand the candidate's research program to include basic and clinical investigations of tDCS-induced plasticity and its potential to facilitate speech motor learning in unimpaired and impaired speakers. The research plan provides an empirical foundation for this research program by investigating the interaction of tDCS and practice-induced speech motor learning. The long-term goal of this research is to develop effective intervention approaches for individuals with acquired speech impairment by combining theoretically-guided intervention with treatment-enhancing neuromodulation techniques. The main objective of this proposal is to establish a best-practice approach for using tDCS to support speech motor learning. The central hypothesis of this proposal is that non-invasive neuromodulation can enhance speech motor learning, including treatment outcomes for targeted interventions for acquired speech impairment. The rationale for the proposed research is that understanding the interaction between neuromodulation and speech motor learning may help determine the most effective approach to enhancing stroke treatment outcomes while extending our basic science knowledge of the relationship between speech and non-speech motor learning. The proposed research is significant because it will enable the development of intervention procedures that maximize recovery from acquired speech impairment, combining targeted therapy with tDCS to unmask the residual capacity for cortical plasticity in chronic stroke survivors. The proposed research is relevant to that part of NIH's mission that pertains to developing fundamental knowledge that will potentially help to reduce the burdens of human disability.

PROJECT SUMMARY/ABSTRACT Stroke is a leading cause of disability in the United States, frequently leading to speech impairment that creates barriers to participation in professional, social, and family settings. While recovery can be promoted with speech motor learning treatment, residual disability remains a prominent issue. The long-term goal of this research is to enhance intervention outcomes for individuals with acquired speech impairment by combining theoretically-guided behavioral intervention with targeted neuromodulation. The main objectives of this proposal are to verify the role of left ventral premotor and motor cortices in speech motor learning and to establish that transcranial direct current stimulation (tDCS) can enhance speech motor learning treatment by strengthening the cortical speech network. The central hypothesis of this proposal is that speech recovery in chronic stroke can be improved by stimulating perilesional left ventral premotor and motor cortices, thereby promoting their engagement during speech motor learning treatment and strengthening the cortical speech network through associative learning. The central hypothesis will be tested by pursuing three specific aims: 1) Establish the neural regions that underlie tDCS-facilitated speech motor learning; 2) Determine the extent to which active tDCS with individualized electrode placement can enhance speech motor learning intervention relative to sham tDCS in impaired speakers with apraxia of speech; and 3) Determine the functional connectivity changes associated with speech motor learning-based intervention with active vs. sham tDCS in impaired speakers with apraxia of speech. Under the first aim, the proposed research will systematically verify the role of left ventral premotor and motor cortices in tDCS-facilitated speech motor learning using three controls: electrode polarity, electrode position, and presence of active current. For the second aim, single- subject intervention experiments will be used to evaluate the extent to which tDCS enhances apraxia treatment outcomes, using individualized current modeling to target left ventral premotor and motor cortices. The third aim determines the extent to which the treatment conditions in Aim 2 can change functional connectivity measured with resting-state functional neuroimaging. The proposed research is innovative, in the applicant's opinion, because it combines practice-based speech treatment with targeted tDCS to intensify Hebbian plasticity and measures the extent to which this approach changes functional connectivity in the speech network. This research will be significant because it will establish the combined effectiveness of speech motor learning treatment and tDCS in AOS, an understudied condition. Understanding the interaction of treatment and neuromodulation will build capacity to optimize chronic stroke recovery, with direct application to enhancing speech skills to improve communication ability and quality of life.