Current direction in TMS revisited: Behavior

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activating bladder contractions from the IVP baseline in partially filled bladder, DBSs on PnO and PPTg at higher stimulation intensities (2.5-5 V) exhibited a higher successful rate and larger contraction area evocation. Taken together of these results, the DBS target on PPTg with low stimulation intensities exhibited the most efficient to suppress the reflexive isovolumetric bladder contractions compared to those of other targets. In addition, PPTg DBS at higher stimulation intensities produced a stable successful rate and high potency for activating bladder contraction. These findings suggested that PPTg might be a promising DBS target for developing new neuromodulatory approaches for the treatment of bladder dysfunctions in the future. Keywords: Bladder dysfunction,, deep brain stimulation, isovolumetric intravesical pressure, micturition reflex [0100] INFLUENCE OF CORTICAL ELECTRICAL STIMULATION ON NEURAL PLASTICITY IN A RAT MODEL OF TRAUMATIC BRAIN INJURY Chih-Wei Peng 1, 2, Shih-Ching Chen 2, 3, Tsung-Hsun Hsieh 4. 1 School of Biomedical Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei, Taiwan; 2 Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; 3 Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taiwan; 4 Department of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan Traumatic brain injury (TBI) is a growing public health concern, with increasing needs for more rigorous measures to quantify changes in the brain post-injury. Electrophysiologic methods, and in particular, transcranial magnetic stimulation (TMS) or cortical electrical stimulation (CES), have been demonstrated to provide prognostic value in several neurological disorders. However, no study has been reported to quantify the electrophysiological changes by using CES method following TBI. This study investigated corticomotor excitability and inhibition in TBI rat model. Cortical excitability was studied in 16 TBI and in 16 normal rats using paired pulses CES. The parameters of testing included resting motor threshold (RMT), recruitment curve (REC) of motor evoked potential (MEP) and long-interval cortical inhibition (LICI) at long intervals (50, 100 and 200 ms). Furthermore, the changes of motor plasticity induced by intermittent theta burst stimulation (iTBS) were also tested in in normal and TBI animals. In results, the TBI group overall revealed a lower RMT and narrower recruitment curves compared to normal rats (p<0.05). The alterations in LICI were more pronounced in TBI rats (p<0.05). In addition, MEPs enhanced immediately after iTBS in normal rats for 30 minutes (p<0.05). In TBI rats, MEPs maintained the same level after iTBS without obvious change. These results showed that TBI rats had less response to iTBS and revealed that motor plasticity was reduced in TBI rats. In Conclusion, this study was the first to demonstrate differences in motor plasticity and intracortical inhibition in TBI animal model. Based on our results, brain injury may alter the neural activity in electrophysiological performance. Longitudinal studies in individuals with TBI would be valuable to identify this hypothesis further, which might provide prognostic biomarkers and suggest novel therapeutic strategies. Keywords: cortical electrical stimulation, long-interval cortical inhibition, motor evoked potential, theta burst stimulation [0102] MODULATING THE SENSE OF AGENCY BY TRANSCRANIAL DIRECT CURRENT STIMULATION

manipulating a range of task parameters related to action selection and action outcomes changes the perceived temporal relationship between a voluntary action and its sensory outcome, using the ‘intentional binding’ effect, that is believed to be an implicit measure of agency. Participants perceived the outcome as shifted towards the action that caused them, relative to control conditions with outcome but no actions. In the first experiment, this ‘intentional binding’ was diminished by anodal stimulation of the left angular gyrus (AG) but not left dLPFC. Experiment 2, using a different cathodal placement, found a similar pattern. Results of the Experiment 3 replicated the results of the first experiment and also suggested that left, but not right AG is mainly responsible for action-outcome matching. Experiments 4-9 investigated the role of dLPFC in a context where participants choose among several action alternatives. Meta-analysis of our own data showed that anodal stimulation of dLPFC increased the temporal binding of actions towards outcomes in the subset of studies involving endogenous action selection, but not in the other studies. These findings provide causal evidence that the left AG plays a key role in the perceptual experience of agency. dLPFC, may also contribute to sense of agency but only when participants select between multiple actions. This enhanced feeling of control over voluntary actions could be related to the observed therapeutic effects of frontal tDCS in depression. Keywords: tDCS, sense of agency, time perception, action selection [0103] THE EFFECT OF STIMULATION PARAMETERS IN PREFRONTAL TDCS RESEARCH ON COGNITION J. Dedoncker*1, A. Brunoni 2, C. Baeken 1, 3, M. Vanderhasselt 1, 3. 1 Ghent ~o Paulo, Brazil; 3 Free University of University, Belgium; 2 University of Sa Brussels, Belgium Introduction: As research into the effects of transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) on cognitive performance is exponentially increasing, so is the methodological heterogeneity in these studies. Importantly, this might influence the outcome effects of tDCS. Therefore, we aimed to systematically examine the influence of technical stimulation parameters on DLPFC-tDCS effects. Methods: We performed a systematic review and meta-analysis of tDCS studies targeting the DLPFC published from the first data available to February 2016. Only single-session, sham-controlled, within-subject studies reporting the effects of tDCS on cognition in healthy and neuropsychiatric cohorts were included. Results: Evaluation of 61 studies showed that single-session anodal tDCS but not cathodal tDCS - leads to faster and more accurate responding on cognitive tasks. Whereas sub-analyses specified that healthy individuals responded faster following anodal tDCS, patients responded more accurate. Importantly, the effects of anodal tDCS - but not cathodal tDCS - were influenced by different stimulation parameters in healthy samples vs. patients. In healthy individuals, increased current density and density charge resulted in improved accuracy, most prominently in females. For neuropsychiatric patients, task performance during anodal tDCS (i.e. online) compared to task performance following anodal tDCS (i.e. offline) resulted in stronger increases in accuracy rates. Conclusions: Following single-session anodal tDCS, healthy individuals respond faster, but not more accurate on cognitive tasks. In contrast, patients respond more accurate, but not faster. Importantly, more intense stimulation protocols (i.e. increased current density/charge) may increase cognitive performance following single-session anodal tDCS in healthy e female e participants. Possibly due to synergistic effects of tDCS and the execution of cognitive tasks, patients may benefit more from an online task paradigm. Keywords: Transcranial Direct Current Stimulation, Dorsolateral Prefrontal Cortex, Stimulation Parameters, Meta-Analysis

N. Khalighinejad*, P. Haggard. University College London, UK The sense of controlling one’s own action is referred to as ‘sense of agency’. Many neurological and psychiatric disorders involve abnormalities of agency: schizophrenic patients often report that their actions are imposed on them by another agent. We designed a series of studies using transcranial direct current stimulation (tDCS) to modulate the key brain circuits underlying the control of action.155 participants were tested in nine separate experiments. We assessed how

[0105] CURRENT DIRECTION IN TMS REVISITED: BEHAVIOR R. Hannah*. UCL Institute of Neurology, UK Introduction: A recent experiment investigated for the first time whether the excitatory synaptic inputs to corticospinal neurons (CSNs) activated by posterior-anterior (PA) and anterior-posterior (AP) currents participated in

Abstracts / Brain Stimulation 10 (2017) 346e540

different types of behaviour. Putatively preconditioning the excitability of PA- and AP-inputs affected learning of a ballistic thumb acceleration task and a visuomotor adaptation task, respectively. The implication is that different inputs to CSNs subserve different forms of motor learning. Here we used a more direct approach to examining the functional role of PAand AP-inputs, by testing whether MEPs evoked by AP and PA pulses were modulated differently during the warning and reaction period of various reaction time tasks (choice, simple and Go/No Go). Methods: Participants received a visual warning signal prior to a visual imperative signal to which they responded by flexing the index finger of the right or left hand. TMS pulses evoked MEPs in the right first dorsal interosseous (FDI) muscle at various times after the warning and imperative signals. Experiments were completed with weak background contraction to enable the use of low stimulus intensities, and ensure the selective recruitment of PA- and AP-inputs. Results: MEPs evoked by AP pulses had longer onset latencies (~1.5 ms) than those evoked by PA pulses. When the right hand was a potential respondent AP MEPs showed a preparatory inhibition after the warning, perhaps to prevent premature initiation of a response, whereas PA-evoked MEPs were unaffected. Discussion: The longer latency of AP versus PA MEPs confirmed the selective recruitment of different inputs to CSNs during the tasks. The present data showed there is a selective suppression of just one set of inputs, AP-inputs, when a preparing/delaying a potential response. This provides further evidence of specific functional roles of AP- and PA-sensitive inputs in motor behaviour. Keywords: Motor control, Motor cortex, Current direction [0106] LEVERAGING GROUP DIFFERENCES TO STUDY THE MECHANISM UNDERLYING THE EFFECTS OF TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) M.E. Berryhill*, H. Arciniega. University of Nevada, USA Studies applying transcranial direct current stimulation (tDCS) during cognitive tasks are less robust and less predictable than when similar protocols are applied to motor questions. We have found that what participants bring to the lab predicts different patterns of responses after a single tDCS protocol. In the case of working memory (WM), participants who scored well on an independent measure of WM capacity showed benefits after single sessions of anodal and cathodal tDCS over the right parietal lobe when compared to the sham control condition. In contrast, those who had low WM capacity performed worse after anodal and cathodal tDCS. In contrast, in longitudinal studies involving multiple sessions of anodal frontal, parietal or frontoparietal tDCS, we find general benefits across participants. Together, these observations introduce a mystery: what mechanism(s) accounts for these sorts of group differences and why do they seem to dissipate after multiple sessions? In a first study, we tested whether pre-existing differences in resting state connectivity known to correlate with WM capacity would also predict initial and longitudinal effects of anodal tDCS over frontal sites. We found behavior-connectivity associations in default mode network regions previously associated with WM performance. Secondly, we investigated whether tDCS-linked WM benefits could be predicted by the rate of dopamine metabolism in frontal regions. This study examined the relationship between a single nucleotide polymorphism (COMT val158met) and WM benefits after longitudinal tDCS. Here, genotype predicted the nature of WM performance gains such that greater gains were observed where performance was weakest at baseline. In summary, to understand how tDCS influences cognitive performance it is important to consider additional factors, including demographic, intellectual, and genetic, to refine predictions regarding who will benefit from tDCS and how. Solving these riddles is an essential precursor to validating the technique and prior to developing translational interventions. Keywords: Working memory, cognitive neuroscience, cognitive training, genotype

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[0108] TRANSCRANIAL STATIC MAGNETIC FIELD STIMULATION OVER THE PRIMARY MOTOR CORTEX DECREASES CORTICAL NOCICEPTIVE PROCESSING H. Kirimoto*, H. Tamaki, N. Otsuru, K. Yamashiro, H. Onishi. Niigata University of Health and Welfare, Japan Introduction: The primary motor cortex (M1) in the human brain can be modulated by the application of transcranial static magnetic field stimulation (tSMS) through the scalp (Oliviero et al., J Physiology, 2011). We previously reported that different components of somatosensory evoked potentials (SEP) are reduced according to the tSMS stimulation site: for instance, tSMS over the C3 modulates the N20 component of SEPs (Kirimoto et al., Brain Stimulation, 2014), while the amplitude of N33 is affected by tSMS over the M1 (Kirimoto et al., Scientific Reports, 2016). This study investigated the possibility of non-invasive modulation of intra-epidermal electrical stimulation-evoked potentials (iES-EPs) by the application of tSMS over the primary motor and somatosensory cortices in healthy humans. Methods: tSMS and sham stimulation over the M1 or S1 were applied in 18 subjects (12 males and 6 females, 20-32 years old) for periods of 15 min. EPs following iES of the right dorsum of the hand were recorded before, immediately after and 10 min after tSMS from sites Cz. For the M1 stimulation, the NdFeB magnet was centred over the representational field of the right abductor pollicis brevis muscle. For the S1 stimulation, magnet was centred 2.5 cm posterior to the C3 (C3’). For iES, we used three concentric bipolar needle electrodes placed 6 mm apart, which can selectively stimulate Ad fibres (Inui et al., Pain, 2002). Results: Amplitudes of iES-EPs significantly decreased immediately after the 15-min period of tSMS over M1 by up to 20%, while tSMS over S1 and sham stimulation had no effect on iES-EPs. Conclusions: Our results suggest that tSMS over M1 could modulate cortical nociceptive processing. tSMS may have potential as a new noninvasive brain stimulation tool in chronic pain treatment alongside conventional methods, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Keywords: Transcranial static magnetic field stimulation, cortical nociceptive processing, pain [0109] SEQUENTIAL THETA BURST STIMULATION CHANGES LANGUAGE FUNCTION AFTER STROKE - PRELIMINARY ANALYSIS IN CHINESE SURVIVORS W. He*1, K. Lee 1, T. Leung 2,1, H. Leung 2,1, Q. Zhang 3, 4, L. Wong 2,1. 1 The Chinese University of Hong Kong, Hong Kong; 2 Prince of Wales Hospital, Hong Kong; 3 Capital Medical University, China; 4 China Rehabilitation Research Center, China Introduction: Theta burst stimulation (TBS) is a patterned repetitive transcranial magnetic stimulation (rTMS) protocol with relatively short stimulation period and strong power. Controlled trial of sequential TBS in post-stroke aphasia has been scarce. We aimed to investigate the potential therapeutic effect of consecutive suppressive-facilitatory TBS on language outcome after stroke. Methods: We allocated 21 right-handed aphasic stroke patients with left hemispheric infarction into there interventional groups: 1) cTBS over right homologue Broca’s area followed by iTBS over Broca’s area, plus 30 minutes conventional one-to-one speech therapy (group A, TBS+ST); 2) group B, TBS only; or 3) group C, ST only. The intervention was performed one session per day. We assessed language ability by Western Aphasic Battery at baseline and after 10 consecutive sessions of intervention. Results: Language ability was improved significantly in all three groups after intervention (pa¼0.028, pb¼0.043, pc¼0.005, Wilcoxon Signed Ranks Test). No difference in treatment effects was found among the three groups (p¼0.15, Kruskal-Wallis Test). In the subgroup of patients with stroke onset more than three months (n¼12), one-way ANOVA showed significant