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Neural Changes Following Transcranial Direct Current Stimulation Combined with Reading Treatment: Evidence from ERPs
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Abstracts / Brain Stimulation 10 (2017) e21ee45
Parra 1. 1 Department of Biomedical Engineering, City College of the City University of New York, New York, NY, 10031, USA; 2 Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY, 10016, USA; 3 Department of Neurology, Mayo Clinic, Rochester, MN, 55902, USA
Abstract Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. Here we measure electric potentials intracranially in ten epilepsy patients and estimate electric fields across the entire brain by leveraging calibrated current-flow models. Electric field magnitudes at the cortical surface reach values of 0.4 V/m, which is at the lower limit of effectiveness in animal studies. When individual anatomy is taken into account, the predicted electric field magnitudes correlate with the recorded values (r¼0.89 and r¼0.84 in cortical and depth electrodes, respectively). Modeling white matter anisotropy and different skull compartments does not improve accuracy, but correct magnitude estimates require an adjustment of conductivity values used in the literature. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation for targeting of stimulation and interpretation of clinical trials. Abstract #19 ELECTROPHYSIOLOGICAL MECHANISMS OF TDCS MODULATION OF EXECUTIVE FUNCTIONS Laura Dubreuil-Vall*1, 2, 3, Peggy Chau 2, Alik Widge 2, Giulio Ruffini 1, Joan Camprodon 2. 1 Neuroelectrics, United States; 2 Massachusetts General Hospital, United States; 3 Universitat de Barcelona, Catalonia, Spain
Abstract Introduction Cognitive deficits are common across neuropsychiatric disorders and a primary cause of functional disability. Nevertheless, clinicians have limited therapeutic options to facilitate cognitive enhancement, particularly of executive functions. tDCS is emerging as a promising tool for the treatment of dysexecutive syndromes. The successful development of such novel therapies requires an understanding of its mechanisms of action and the key targets that, when engaged, drive the therapeutic response.
Methods We investigated the role of tDCS in modulating executive functions in 20 healthy adults, who received three different tDCS stimulation conditions over three separate visits: sham, anodal tDCS on the right DLPFC and the left DLPFC. Participants performed the Flanker task and Multisource Interference Task with International Affective Picture System (MSIT-IAPS) before and after receiving tDCS. We measured behavioral responses and EEG during the task, and calculated ERPs over Fz.
Results For Flanker incongruent trials, Anodal Left stimulation lead to significantly faster RT and an increase in P300 amplitude, while Sham lead to no significant changes in RT or P300 amplitude. For Flanker congruent trials and for all trials in MSIT-IAPS, Anodal Left and Right stimulation lead to no improvement in RT and an increase in P200 amplitude, while Sham lead to a significant faster RT and no significant changes in P200 amplitude. a
First authors contributed equally.
Discussion We describe the modulation of ERPs related to executive functions by anodal tDCS to the DLPFC in healthy adults, correlated with a modulation in task performance. These physiological markers may represent therapeutic targets for pro-cognitive treatments. Abstract #20 NEURAL CHANGES FOLLOWING TRANSCRANIAL DIRECT CURRENT STIMULATION COMBINED WITH READING TREATMENT: EVIDENCE FROM ERPS Grace Lee 1, Shrida Sahadevan 2, Esther Kim 2, 3, 4. 1 Faculty of Sciences, Canada; 2 Faculty of Rehabilitation Medicine, Canada; 3 Department of Communication Sciences & Disorders, Canada; 4 Neuroscience & Mental Health Institute, University of Alberta, Canada
Abstract Aphasia is a communication impairment caused by damage to language areas in the brain. Pairing traditional speech therapy with non-invasive brain stimulation, specifically Transcranial Direct Current Stimulation (tDCS), has been shown to enhance rehabilitation outcomes. This study examines the impact of tDCS coupled with reading treatment on language outcomes of people with aphasia, and investigates neural changes (as measured by event-related potentials; ERPs) related to intensive treatment delivery. Our participant (RJ) had nonfluent aphasia and received a total of 60 hours of reading treatment, in conjunction with anodal-tDCS and shamtDCS phases in a crossover design. Following both phases of treatment, RJ demonstrated clinically significant improvement in spoken language, gains in reading comprehension, and evidence of improved sublexical processing. Behavioural results were corroborated by electrophysiological data suggesting neural changes following treatment. There was a greater mean N400 amplitude when reading semantically incongruent sentences after therapy, suggesting improved semantic integration. Moreover, RJ demonstrated changes in neural processing which more closely resembled healthy, demographically matched controls following treatment. Post treatment topography plots show clearer delineation of activation, suggesting a greater recruitment of neural resources for reading. Positive treatment effects were further enhanced and maintained when treatment was combined with a-tDCS in the occipiotemporal cortex. These data provide evidence of treatment induced neural plasticity in chronic aphasia, and extends the literature supporting intensive treatment to the written language domain. Abstract #21 THE EXPERIENCE OF DISGUST SUPPRESSES THE EXCITABILITY OF THE TONGUE MOTOR CORTEX Carmelo M. Vicario*1, 2, Alessio Avenanti 3, 4. 1 Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, LL57 2DG, United Kingdom; 2 School of Psychology, University of Tasmania, Hobart, Tasmania, Australia; 3 Department of Psychology and Center for Studies and Research in Cognitive Neuroscience, University of Bologna, Cesena Campus, 47521, Cesena, Italy; 4 IRCCS Fondazione Santa Lucia, 00179, Roma, Italy E-mail addresses: [email protected] (C.M. Vicario), [email protected] (A. Avenanti).
Abstract The tongue holds a unique role in gustatory disgust. However, it is unclear whether the tongue representation in the motor cortex (tM1) is affected by the sight of distaste-related stimuli. Using transcranial magnetic stimulation (TMS) in healthy humans, we recorded tongue motor-evoked potentials (MEPs) as an index of tM1 cortico-hypoglossal excitability. MEPs were recorded while participants viewed pictures associated with gustatory disgust and revulsion (i.e., rotten foods and faces expressing distaste), nonoral-related disgusting stimuli and control stimuli. We found that oral-
Abstracts / Brain Stimulation 10 (2017) e21ee45
Parra 1. 1 Department of Biomedical Engineering, City College of the City University of New York, New York, NY, 10031, USA; 2 Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY, 10016, USA; 3 Department of Neurology, Mayo Clinic, Rochester, MN, 55902, USA
Abstract Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. Here we measure electric potentials intracranially in ten epilepsy patients and estimate electric fields across the entire brain by leveraging calibrated current-flow models. Electric field magnitudes at the cortical surface reach values of 0.4 V/m, which is at the lower limit of effectiveness in animal studies. When individual anatomy is taken into account, the predicted electric field magnitudes correlate with the recorded values (r¼0.89 and r¼0.84 in cortical and depth electrodes, respectively). Modeling white matter anisotropy and different skull compartments does not improve accuracy, but correct magnitude estimates require an adjustment of conductivity values used in the literature. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation for targeting of stimulation and interpretation of clinical trials. Abstract #19 ELECTROPHYSIOLOGICAL MECHANISMS OF TDCS MODULATION OF EXECUTIVE FUNCTIONS Laura Dubreuil-Vall*1, 2, 3, Peggy Chau 2, Alik Widge 2, Giulio Ruffini 1, Joan Camprodon 2. 1 Neuroelectrics, United States; 2 Massachusetts General Hospital, United States; 3 Universitat de Barcelona, Catalonia, Spain
Abstract Introduction Cognitive deficits are common across neuropsychiatric disorders and a primary cause of functional disability. Nevertheless, clinicians have limited therapeutic options to facilitate cognitive enhancement, particularly of executive functions. tDCS is emerging as a promising tool for the treatment of dysexecutive syndromes. The successful development of such novel therapies requires an understanding of its mechanisms of action and the key targets that, when engaged, drive the therapeutic response.
Methods We investigated the role of tDCS in modulating executive functions in 20 healthy adults, who received three different tDCS stimulation conditions over three separate visits: sham, anodal tDCS on the right DLPFC and the left DLPFC. Participants performed the Flanker task and Multisource Interference Task with International Affective Picture System (MSIT-IAPS) before and after receiving tDCS. We measured behavioral responses and EEG during the task, and calculated ERPs over Fz.
Results For Flanker incongruent trials, Anodal Left stimulation lead to significantly faster RT and an increase in P300 amplitude, while Sham lead to no significant changes in RT or P300 amplitude. For Flanker congruent trials and for all trials in MSIT-IAPS, Anodal Left and Right stimulation lead to no improvement in RT and an increase in P200 amplitude, while Sham lead to a significant faster RT and no significant changes in P200 amplitude. a
First authors contributed equally.
Discussion We describe the modulation of ERPs related to executive functions by anodal tDCS to the DLPFC in healthy adults, correlated with a modulation in task performance. These physiological markers may represent therapeutic targets for pro-cognitive treatments. Abstract #20 NEURAL CHANGES FOLLOWING TRANSCRANIAL DIRECT CURRENT STIMULATION COMBINED WITH READING TREATMENT: EVIDENCE FROM ERPS Grace Lee 1, Shrida Sahadevan 2, Esther Kim 2, 3, 4. 1 Faculty of Sciences, Canada; 2 Faculty of Rehabilitation Medicine, Canada; 3 Department of Communication Sciences & Disorders, Canada; 4 Neuroscience & Mental Health Institute, University of Alberta, Canada
Abstract Aphasia is a communication impairment caused by damage to language areas in the brain. Pairing traditional speech therapy with non-invasive brain stimulation, specifically Transcranial Direct Current Stimulation (tDCS), has been shown to enhance rehabilitation outcomes. This study examines the impact of tDCS coupled with reading treatment on language outcomes of people with aphasia, and investigates neural changes (as measured by event-related potentials; ERPs) related to intensive treatment delivery. Our participant (RJ) had nonfluent aphasia and received a total of 60 hours of reading treatment, in conjunction with anodal-tDCS and shamtDCS phases in a crossover design. Following both phases of treatment, RJ demonstrated clinically significant improvement in spoken language, gains in reading comprehension, and evidence of improved sublexical processing. Behavioural results were corroborated by electrophysiological data suggesting neural changes following treatment. There was a greater mean N400 amplitude when reading semantically incongruent sentences after therapy, suggesting improved semantic integration. Moreover, RJ demonstrated changes in neural processing which more closely resembled healthy, demographically matched controls following treatment. Post treatment topography plots show clearer delineation of activation, suggesting a greater recruitment of neural resources for reading. Positive treatment effects were further enhanced and maintained when treatment was combined with a-tDCS in the occipiotemporal cortex. These data provide evidence of treatment induced neural plasticity in chronic aphasia, and extends the literature supporting intensive treatment to the written language domain. Abstract #21 THE EXPERIENCE OF DISGUST SUPPRESSES THE EXCITABILITY OF THE TONGUE MOTOR CORTEX Carmelo M. Vicario*1, 2, Alessio Avenanti 3, 4. 1 Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, LL57 2DG, United Kingdom; 2 School of Psychology, University of Tasmania, Hobart, Tasmania, Australia; 3 Department of Psychology and Center for Studies and Research in Cognitive Neuroscience, University of Bologna, Cesena Campus, 47521, Cesena, Italy; 4 IRCCS Fondazione Santa Lucia, 00179, Roma, Italy E-mail addresses: [email protected] (C.M. Vicario), [email protected] (A. Avenanti).
Abstract The tongue holds a unique role in gustatory disgust. However, it is unclear whether the tongue representation in the motor cortex (tM1) is affected by the sight of distaste-related stimuli. Using transcranial magnetic stimulation (TMS) in healthy humans, we recorded tongue motor-evoked potentials (MEPs) as an index of tM1 cortico-hypoglossal excitability. MEPs were recorded while participants viewed pictures associated with gustatory disgust and revulsion (i.e., rotten foods and faces expressing distaste), nonoral-related disgusting stimuli and control stimuli. We found that oral-