- Email: [email protected]
Direct current stimulation modulates LTP and LTD: activity dependence and dendritic effects
Abstracts / Brain Stimulation 10 (2017) e21ee45
Abstract #8 THE CURRENT LEVEL OF EVIDENCE FOR USING TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) TO IMPROVE NAMING ABILITY IN POSTSTROKE APHASIA: A CRITICAL REVIEW Mohammed F. ALHarbi PhD student*1, 4, Susan Armijo-Olivo PhD 1,2, Esther S. Kim PhD, R.SLP, CCC-SLP 1, 3. 1 Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada; 2 Rehabilitation Research Center, University of Alberta, Edmonton, AB, Canada; 3 Dept. of Communication Sciences and Disorders, University of Alberta, Edmonton, AB, Canada; 4 Department of Audiology and Speech-language pathology, College of Medical Rehabilitation Sciences, Taibah University, Madinah, Saudi Arabia E-mail address: [email protected] (M.F. ALHarbi).
Abstract Purpose Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation tool that can be used to manipulate cortical brain activity to induce measurable behavioral changes. Although there is growing evidence that tDCS combined with behavioural language therapy could boost language recovery in patients with post-stroke aphasia, there is great variability in patient characteristics, treatment protocols, and outcome measures in these studies that poses challenges for analyzing the evidence. The purpose of this study is to critically analyze the methodological rigor of the evidence for using tDCS for post-stroke anomia.
Method This critical review was conducted by searching four databases (MEDLINE, EMBase, PsycINFO, and CINAHL). Seventeen studies fully met the inclusion criteria. Robey and Schultz’s (1998) five- phase model for conducting clinical outcome research was adopted to analyze the current level of evidence. Methodological issues of the studies were also identified.
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Abstract High definition tDCS (HD-tDCS) generates electrical fields using multiple electrodes. Most studies using HD-tDCS have administered stimulation to one brain area for a small number of sessions. The purpose of this trial was to study feasibility, tolerability, and safety of HD-tDCS applied over 2-4 different brain regions and administered daily for a total of 20 sessions in healthy adults. Five healthy adults were recruited (2 females, 3 males, mean age 23.4y). Subjects underwent physical and neurological examination, electrocardiogram, electroencephalogram and IMPACT test before study initiation, during the study and at completion of the study. Four networks were stimulated using HD-tDCS, left and right temporooccipital and left and right frontal. Sessions 1-10 included stimulation of both temporooccipital networks (1mA in week 1, 1.5 mA in week 2 over 20 min/network). Sessions 11-15 included 20 min long stimulations of all 4 networks at 1.5 mA/ network and sessions 16-20 consisted of 2 stimulation cycles on each day of all 4 networks at 1.5 mA/network. Only one network was stimulated at a given time point. All subjects completed the trial. Adverse events were tingling, transient redness, feeling of being stimulated for 2 hrs after one session and one incident of headache. There were no abnormalities detected on EKG, EEG, physical and neurologic exam. The scores in the IMPACT test were similar before and after the 20 stimulation sessions. This pilot trial demonstrates that prolonged daily stimulation of multiple brain regions over 4 consecutive weeks using HD-tDCS is feasible and well tolerated in healthy adults. Abstract #10 DIRECT CURRENT STIMULATION MODULATES LTP AND LTD: ACTIVITY DEPENDENCE AND DENDRITIC EFFECTS Greg Kronberg*1, Morgan Bridi 2, Ted Abel 2, Marom Bikson 1, Lucas C. Parra 1. 1 Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA; 2 Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
Abstract Background
Results The current level of evidence for using tDCS for anomia is at the pre-efficacy level. Lack of proper evaluation of carry-over effect in cross-over studies, lack of or unclear randomization, allocation concealment, and dropout were the main methodological issues that could threaten the validity of the tDCS studies.
Transcranial direct current stimulation (tDCS) has been reported to improve various forms of learning in humans. Stimulation is often applied during training, producing lasting enhancements that are specific to the learned task. These learning effects are thought be mediated by altered synaptic plasticity. However, the effects of DCS during the induction of endogenous synaptic plasticity remain largely unexplored.
Objective Conclusions tDCS has the potential to be an effective treatment for anomia. However, there are several methodological issues have been identified in pre-efficacy studies that pose challenges in determining whether tDCS is a beneficial adjunct to behavioural aphasia therapy. Future studies need to improve the quality of the methods used to investigate the effect of tDCS for anomia. Abstract #9 FEASIBILITY AND DOSE TOLERABILITY OF HIGH DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION IN HEALTHY ADULTS Christopher A. Turski 1, Alanna Kessler-Jones 1, Bruce Hermann 1, David Hsu 1, Jana Jones 1, Susanne Seeger 1, Rick Chappell 2, Chrysanthy Ikonomidou*1. 1 Department of Neurology, Biostatistics and Medical Informatics University of Wisconsin Madison, USA; 2 Department of Statistics, Biostatistics and Medical Informatics University of Wisconsin Madison, USA
Here we are interested in the effects of DCS applied during synaptic plasticity induction.
Methods To model endogenous plasticity we induced long-term potentiation (LTP) and depression (LTD) at Schaffer collateral synapses in CA1 of rat hippocampal slices. Anodal and cathodal DCS at 20 V/m were applied throughout plasticity induction in both apical and basal dendritic compartments.
Results When DCS was paired with concurrent plasticity induction, the resulting plasticity was biased towards potentiation, such that LTP was enhanced and LTD was reduced. Remarkably, both anodal and cathodal stimulation can produce this bias, depending on the dendritic location and type of plasticity induction. Cathodal DCS enhanced LTP in apical dendrites while
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Abstracts / Brain Stimulation 10 (2017) e21ee45
anodal DCS enhanced LTP in basal dendrites. Both anodal and cathodal DCS reduced LTD in apical dendrites. DCS did not affect synapses that were weakly active or when NMDA receptors were blocked.
Conclusions These results highlight the role of DCS as a modulator, rather than inducer of synaptic plasticity, and the dependence of DCS effects on the spatial and temporal properties of endogenous synaptic activity. The relevance of the present results to human tDCS should be validated in future studies. Abstract #11 INDIVIDUAL DIFFERENCES IN TDCS AUGMENTED WORKING MEMORY TRAINING Benjamin Katz 1, a, c, Jacky Au 2, 3, a, c, Martin Buschkuehl 3, Tessa Chelsea Zabel 1, Susanne M. Jaeggi 2, 4, b, John Abagis 1, Jonides 1, b. 1 Department of Psychology, University of Michigan, Ann Arbor, MI, 48109, USA; 2 Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, 92697, USA; 3 MIND Research Institute, Irvine, CA, 92617, USA; 4 School of Education, University of California, Irvine, Irvine, CA, 92697, USA
Abstract There has been significant interest in the use of non-invasive brain stimulation, and in particular transcranial direct current stimulation (tDCS), to improve the outcome of computerized working memory (WM) training. The findings across these recent studies, including meta-analytic work, is mixed, however. One possible explanation for these divergent results that has not been widely explored is the impact of individual difference factors, including baseline ability and motivation. The present research incorporates data from a previous study of tDCS and cognitive training (Au et al., 2016) in which participants trained on a working memory task over 7 days while receiving active or sham stimulation. We measured baseline cognitive ability, gender, training location, and motivation and found significant interactions between both baseline ability and motivation with condition (active or sham) in models predicting the slope of training performance. Abstract #12 TRANSCRANIAL DIRECT CURRENT STIMULATION ALTERS MICROGLIAL MORPHOLOGY IN MICE Tsuneko Mishima*, Yuki Oe, Hiromu Monai, Hajime Hirase. RIKEN Brain Science Institute, Japan
perimeter (5.6%). By contrast, morphological changes were not obvious in urethane- or isoflurane-anesthetized mice even when the stimulus current intensity was 10 times high (1mA/2mm 2 , 10min). Our results parallels with the reduced degree of tDCS-induced astrocytic Ca 2+ surges during deep isoflurane or urethane anesthesia and suggest that and their morphological changes may play a role in long-term effects of tDCS. Abstract #13 OFF-LINE RTMS OF LEFT DORSOLATERAL PREFRONTAL CORTEX REDUCES FOOD CRAVINGS IN FEMALES BUT NOT MALES Valentina Cazzato*1, Huw Williams 2, Stergios Makris 2. 1 School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK; 2 Department of Psychology, Edge Hill University, Ormskirk, UK
Abstract Dysfunction of the left dorsolateral prefrontal cortex (DLFPC) has been crucially implicated in craving for food. Here, we aimed at expanding this result by investigating gender differences in food cravings in female (n¼8; age¼20.38yrs; BMI¼22.54) and male (n¼9; age¼20.67yrs; BMI¼20.89) healthy participants. Off-line repetitive transcranial magnetic stimulation (rTMS; 15 mins, 900 pulses) was administered on the left DLPFC and on the vertex (as control condition) before and after exposure to sweet food. Desire for salty and sweet food consumption was assessed by visual analogue scales (VAS) and calories consumed before and after rTMS. While after vertex-rTMS women expressed higher desire for sweet but not for salty foods with respect to men, desire for food did not change and remained stable before and after DLPFC-rTMS. No differences were observed in the consumed calories after the two rTMS stimulation. Our results provide preliminary evidence of a brain mechanism by which cognitive inhibition decreases the desire for sweet foods and implicates lower ability to suppress cravings in women as a contributing factor to gender differences possibly in binge eating disorder and obesity Abstract #14 THE INFLUENCE OF SHAM REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION ON COMMONLY COLLECTED TMS METRICS IN PATIENTS WITH CHRONIC STROKE David A. Cunningham*1, 2, Jacqueline Cavendish 2, Vishwanath Sankarasubramanian 2, Kelsey A. Potter-Baker 2, Andre G. Machado 3, Ela B. Plow 2, 4. 1 Human Performance & Engineering Research, Kessler Foundation, West Orange, NJ, USA; 2 Dept. of Biomedical Engineering, Lerner Research Inst., Cleveland Clinic, Cleveland, OH, USA; 3 Center for Neurological Restoration, Neurosurgery, Neurological Inst., Cleveland Clinic, Cleveland, OH, USA; 4 Dept. of Physical Medicine & Rehab, Neurological Inst., Cleveland Clinic, Cleveland, OH, USA
Abstract Transcranial direct current stimulation (tDCS) is well-known for polarityspecific modulation of cortical excitability and has been experimentally used in the clinics to treat various brain disorders. However, the cellular and molecular changes induced by such treatment remain largely unknown. Recently, Monai et al. [1] showed that astrocytes, a type of glial cells, elevate Ca 2+ by tDCS and promote cortical plasticity. To investigate how tDCS affects another type of glial cells, microglia, we performed IBA-1 immunohistochemistry in mouse brains that underwent tDCS (0.1mA/ 2mm 2 , 10 min) under awake, urethane-anesthetized, and isofluraneanesthetized conditions. Confocal images of fluorescence labelled microglia were analyzed by a custom-made MATLAB program and ImageJ software(NIH). Morphometric analyses in progress showed that single-dose tDCS under awake condition induces significant morphological alternations of microglia, including shrinked cell body area (7.3%) and increased a b c
Co-First Authors. Co-Senior Authors. Co-Presenting Authors.
Abstract Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used in research to promote recovery for patients with chronic stroke by directly influencing neuronal activity. In research, sham-rTMS is often used to control for a placebo effect by mimicking auditory and somatosensory perception without actually stimulating the brain. Still, the influence of sham-rTMS on neuronal activity measured with single-pulse TMS has been given minimal attention. Therefore, our objective was to study the effect of sham-rTMS on TMS metrics and within-session reliability of these metrics from baseline to post sham-rTMS (absolute difference and intraclass correlation coefficient [ICC]). Sixteen patients with chronic stroke participated in one session of sham-rTMS and one session of no-stimulation. Single-pulse TMS was used to investigate recruitment curves and interhemispheric inhibition upon the contralesional and ipsilesional hemisphere before and immediately following each session. Overall, sham-rTMS did not influence TMS metrics on a group level when compared to no-stimulation. However, we found within-session reliability was reduced following only sham-rTMS.
Abstract #8 THE CURRENT LEVEL OF EVIDENCE FOR USING TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) TO IMPROVE NAMING ABILITY IN POSTSTROKE APHASIA: A CRITICAL REVIEW Mohammed F. ALHarbi PhD student*1, 4, Susan Armijo-Olivo PhD 1,2, Esther S. Kim PhD, R.SLP, CCC-SLP 1, 3. 1 Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada; 2 Rehabilitation Research Center, University of Alberta, Edmonton, AB, Canada; 3 Dept. of Communication Sciences and Disorders, University of Alberta, Edmonton, AB, Canada; 4 Department of Audiology and Speech-language pathology, College of Medical Rehabilitation Sciences, Taibah University, Madinah, Saudi Arabia E-mail address: [email protected] (M.F. ALHarbi).
Abstract Purpose Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation tool that can be used to manipulate cortical brain activity to induce measurable behavioral changes. Although there is growing evidence that tDCS combined with behavioural language therapy could boost language recovery in patients with post-stroke aphasia, there is great variability in patient characteristics, treatment protocols, and outcome measures in these studies that poses challenges for analyzing the evidence. The purpose of this study is to critically analyze the methodological rigor of the evidence for using tDCS for post-stroke anomia.
Method This critical review was conducted by searching four databases (MEDLINE, EMBase, PsycINFO, and CINAHL). Seventeen studies fully met the inclusion criteria. Robey and Schultz’s (1998) five- phase model for conducting clinical outcome research was adopted to analyze the current level of evidence. Methodological issues of the studies were also identified.
e23
Abstract High definition tDCS (HD-tDCS) generates electrical fields using multiple electrodes. Most studies using HD-tDCS have administered stimulation to one brain area for a small number of sessions. The purpose of this trial was to study feasibility, tolerability, and safety of HD-tDCS applied over 2-4 different brain regions and administered daily for a total of 20 sessions in healthy adults. Five healthy adults were recruited (2 females, 3 males, mean age 23.4y). Subjects underwent physical and neurological examination, electrocardiogram, electroencephalogram and IMPACT test before study initiation, during the study and at completion of the study. Four networks were stimulated using HD-tDCS, left and right temporooccipital and left and right frontal. Sessions 1-10 included stimulation of both temporooccipital networks (1mA in week 1, 1.5 mA in week 2 over 20 min/network). Sessions 11-15 included 20 min long stimulations of all 4 networks at 1.5 mA/ network and sessions 16-20 consisted of 2 stimulation cycles on each day of all 4 networks at 1.5 mA/network. Only one network was stimulated at a given time point. All subjects completed the trial. Adverse events were tingling, transient redness, feeling of being stimulated for 2 hrs after one session and one incident of headache. There were no abnormalities detected on EKG, EEG, physical and neurologic exam. The scores in the IMPACT test were similar before and after the 20 stimulation sessions. This pilot trial demonstrates that prolonged daily stimulation of multiple brain regions over 4 consecutive weeks using HD-tDCS is feasible and well tolerated in healthy adults. Abstract #10 DIRECT CURRENT STIMULATION MODULATES LTP AND LTD: ACTIVITY DEPENDENCE AND DENDRITIC EFFECTS Greg Kronberg*1, Morgan Bridi 2, Ted Abel 2, Marom Bikson 1, Lucas C. Parra 1. 1 Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA; 2 Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
Abstract Background
Results The current level of evidence for using tDCS for anomia is at the pre-efficacy level. Lack of proper evaluation of carry-over effect in cross-over studies, lack of or unclear randomization, allocation concealment, and dropout were the main methodological issues that could threaten the validity of the tDCS studies.
Transcranial direct current stimulation (tDCS) has been reported to improve various forms of learning in humans. Stimulation is often applied during training, producing lasting enhancements that are specific to the learned task. These learning effects are thought be mediated by altered synaptic plasticity. However, the effects of DCS during the induction of endogenous synaptic plasticity remain largely unexplored.
Objective Conclusions tDCS has the potential to be an effective treatment for anomia. However, there are several methodological issues have been identified in pre-efficacy studies that pose challenges in determining whether tDCS is a beneficial adjunct to behavioural aphasia therapy. Future studies need to improve the quality of the methods used to investigate the effect of tDCS for anomia. Abstract #9 FEASIBILITY AND DOSE TOLERABILITY OF HIGH DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION IN HEALTHY ADULTS Christopher A. Turski 1, Alanna Kessler-Jones 1, Bruce Hermann 1, David Hsu 1, Jana Jones 1, Susanne Seeger 1, Rick Chappell 2, Chrysanthy Ikonomidou*1. 1 Department of Neurology, Biostatistics and Medical Informatics University of Wisconsin Madison, USA; 2 Department of Statistics, Biostatistics and Medical Informatics University of Wisconsin Madison, USA
Here we are interested in the effects of DCS applied during synaptic plasticity induction.
Methods To model endogenous plasticity we induced long-term potentiation (LTP) and depression (LTD) at Schaffer collateral synapses in CA1 of rat hippocampal slices. Anodal and cathodal DCS at 20 V/m were applied throughout plasticity induction in both apical and basal dendritic compartments.
Results When DCS was paired with concurrent plasticity induction, the resulting plasticity was biased towards potentiation, such that LTP was enhanced and LTD was reduced. Remarkably, both anodal and cathodal stimulation can produce this bias, depending on the dendritic location and type of plasticity induction. Cathodal DCS enhanced LTP in apical dendrites while
e24
Abstracts / Brain Stimulation 10 (2017) e21ee45
anodal DCS enhanced LTP in basal dendrites. Both anodal and cathodal DCS reduced LTD in apical dendrites. DCS did not affect synapses that were weakly active or when NMDA receptors were blocked.
Conclusions These results highlight the role of DCS as a modulator, rather than inducer of synaptic plasticity, and the dependence of DCS effects on the spatial and temporal properties of endogenous synaptic activity. The relevance of the present results to human tDCS should be validated in future studies. Abstract #11 INDIVIDUAL DIFFERENCES IN TDCS AUGMENTED WORKING MEMORY TRAINING Benjamin Katz 1, a, c, Jacky Au 2, 3, a, c, Martin Buschkuehl 3, Tessa Chelsea Zabel 1, Susanne M. Jaeggi 2, 4, b, John Abagis 1, Jonides 1, b. 1 Department of Psychology, University of Michigan, Ann Arbor, MI, 48109, USA; 2 Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, 92697, USA; 3 MIND Research Institute, Irvine, CA, 92617, USA; 4 School of Education, University of California, Irvine, Irvine, CA, 92697, USA
Abstract There has been significant interest in the use of non-invasive brain stimulation, and in particular transcranial direct current stimulation (tDCS), to improve the outcome of computerized working memory (WM) training. The findings across these recent studies, including meta-analytic work, is mixed, however. One possible explanation for these divergent results that has not been widely explored is the impact of individual difference factors, including baseline ability and motivation. The present research incorporates data from a previous study of tDCS and cognitive training (Au et al., 2016) in which participants trained on a working memory task over 7 days while receiving active or sham stimulation. We measured baseline cognitive ability, gender, training location, and motivation and found significant interactions between both baseline ability and motivation with condition (active or sham) in models predicting the slope of training performance. Abstract #12 TRANSCRANIAL DIRECT CURRENT STIMULATION ALTERS MICROGLIAL MORPHOLOGY IN MICE Tsuneko Mishima*, Yuki Oe, Hiromu Monai, Hajime Hirase. RIKEN Brain Science Institute, Japan
perimeter (5.6%). By contrast, morphological changes were not obvious in urethane- or isoflurane-anesthetized mice even when the stimulus current intensity was 10 times high (1mA/2mm 2 , 10min). Our results parallels with the reduced degree of tDCS-induced astrocytic Ca 2+ surges during deep isoflurane or urethane anesthesia and suggest that and their morphological changes may play a role in long-term effects of tDCS. Abstract #13 OFF-LINE RTMS OF LEFT DORSOLATERAL PREFRONTAL CORTEX REDUCES FOOD CRAVINGS IN FEMALES BUT NOT MALES Valentina Cazzato*1, Huw Williams 2, Stergios Makris 2. 1 School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK; 2 Department of Psychology, Edge Hill University, Ormskirk, UK
Abstract Dysfunction of the left dorsolateral prefrontal cortex (DLFPC) has been crucially implicated in craving for food. Here, we aimed at expanding this result by investigating gender differences in food cravings in female (n¼8; age¼20.38yrs; BMI¼22.54) and male (n¼9; age¼20.67yrs; BMI¼20.89) healthy participants. Off-line repetitive transcranial magnetic stimulation (rTMS; 15 mins, 900 pulses) was administered on the left DLPFC and on the vertex (as control condition) before and after exposure to sweet food. Desire for salty and sweet food consumption was assessed by visual analogue scales (VAS) and calories consumed before and after rTMS. While after vertex-rTMS women expressed higher desire for sweet but not for salty foods with respect to men, desire for food did not change and remained stable before and after DLPFC-rTMS. No differences were observed in the consumed calories after the two rTMS stimulation. Our results provide preliminary evidence of a brain mechanism by which cognitive inhibition decreases the desire for sweet foods and implicates lower ability to suppress cravings in women as a contributing factor to gender differences possibly in binge eating disorder and obesity Abstract #14 THE INFLUENCE OF SHAM REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION ON COMMONLY COLLECTED TMS METRICS IN PATIENTS WITH CHRONIC STROKE David A. Cunningham*1, 2, Jacqueline Cavendish 2, Vishwanath Sankarasubramanian 2, Kelsey A. Potter-Baker 2, Andre G. Machado 3, Ela B. Plow 2, 4. 1 Human Performance & Engineering Research, Kessler Foundation, West Orange, NJ, USA; 2 Dept. of Biomedical Engineering, Lerner Research Inst., Cleveland Clinic, Cleveland, OH, USA; 3 Center for Neurological Restoration, Neurosurgery, Neurological Inst., Cleveland Clinic, Cleveland, OH, USA; 4 Dept. of Physical Medicine & Rehab, Neurological Inst., Cleveland Clinic, Cleveland, OH, USA
Abstract Transcranial direct current stimulation (tDCS) is well-known for polarityspecific modulation of cortical excitability and has been experimentally used in the clinics to treat various brain disorders. However, the cellular and molecular changes induced by such treatment remain largely unknown. Recently, Monai et al. [1] showed that astrocytes, a type of glial cells, elevate Ca 2+ by tDCS and promote cortical plasticity. To investigate how tDCS affects another type of glial cells, microglia, we performed IBA-1 immunohistochemistry in mouse brains that underwent tDCS (0.1mA/ 2mm 2 , 10 min) under awake, urethane-anesthetized, and isofluraneanesthetized conditions. Confocal images of fluorescence labelled microglia were analyzed by a custom-made MATLAB program and ImageJ software(NIH). Morphometric analyses in progress showed that single-dose tDCS under awake condition induces significant morphological alternations of microglia, including shrinked cell body area (7.3%) and increased a b c
Co-First Authors. Co-Senior Authors. Co-Presenting Authors.
Abstract Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used in research to promote recovery for patients with chronic stroke by directly influencing neuronal activity. In research, sham-rTMS is often used to control for a placebo effect by mimicking auditory and somatosensory perception without actually stimulating the brain. Still, the influence of sham-rTMS on neuronal activity measured with single-pulse TMS has been given minimal attention. Therefore, our objective was to study the effect of sham-rTMS on TMS metrics and within-session reliability of these metrics from baseline to post sham-rTMS (absolute difference and intraclass correlation coefficient [ICC]). Sixteen patients with chronic stroke participated in one session of sham-rTMS and one session of no-stimulation. Single-pulse TMS was used to investigate recruitment curves and interhemispheric inhibition upon the contralesional and ipsilesional hemisphere before and immediately following each session. Overall, sham-rTMS did not influence TMS metrics on a group level when compared to no-stimulation. However, we found within-session reliability was reduced following only sham-rTMS.