- Email: [email protected]
Effects of propranolol on cortical excitability: a TMS study
478
Abstracts / Brain Stimulation 10 (2017) 346e540
distribution in an attempt to characterise variance in tDCS response. To better quantify the interindividual variability rooted in anatomical differences, we used finite-element modelling (SimNIBS software package; Thielscher, Antunes, & Saturnino, 2015) to calculate individual current distribution based on participant-specific T1- and T2-weighted structural MRI scans. We adapted a psychophysical visual perimetry task in order to reduce participant performance to a single metric and measured the behavioural performance of young, healthy participants while anodal, cathodal and sham tDCS was applied to the visual cortex. Contrast sensitivity was then assessed at multiple visual field positions before, during and after tDCS. Thus, the present study relates the findings from individual electric field modelling to behavioural results obtained in the same participants. Future implications for the development of dose-dependent approaches to transcranial electrical stimulation are discussed. Keywords: transcranial direct current stimulation, visual cortex, finiteelement modelling, contrast sensitivity
on the selected electrode, an appropriate stimulation output in real time. Thus, the device is able to perform closed loop algorithms on local electrodes. Results: The ECoG MEAs have a total device thickness as low as 6 mm and adhere tightly to the brain surface. The PEDOT-CNT coating has very low impedance (7.2±2.2 kU @ 100Hz for 50mm diameter electrodes), allowing high signal to noise ratio signal recording. It also shows high charge transfer capability (>30mC/cm2), enabling high current density stimulation on ultrathin polymeric supports without delamination. The electronic board allows to record up to 32 channels at a maximum sampling rate of 1 MSample/s shared on the selected inputs or inject up to 2 mA current through the electrodes. Finally, the synergy of recording and stimulation on a single board allows the implementation of low latency closed loop algorithm (<500 ms). Discussion: The presented stimulation/recording platform is a powerful and flexible tool for brain-computer interfaces for clinical applications. Keywords: ECoG, PEDOT-CNT, MEA, closed-loop
[0548] THE INFLUENCE OF THETA BURST STIMULATION ON COGNITIVE FUNCTIONS AS ASSESSED BY FMRI STROOP TASK
[0552] SUCCESSFUL TREATMENT OF BIPOLAR DEPRESSIVE DISORDER PATIENTS USING TRANSCRANIAL MAGNETIC STIMULATION: RESULTS FROM AN URBAN TMS CLINIC
L. Anderkova*, M. Gajdos, E. Koritakova, I. Rektorova. Masaryk University, Czech Republic
R. McMullen*, S. Agarwal. 1 TMS Brain Care, USA; Center, USA
Introduction: The aim of this study was to investigate the effects of theta burst stimulation (TBS) on cognitive functions as assessed by fMRI Stroop task. Methods: Twelve healthy young subjects participated in the TBS-fMRI study. Each participant received a session of stimulation of the right inferior frontal gyrus (IFG), the left superior parietal lobule (SPL), and the vertex (VTX) using continuous TBS (cTBS) or intermittent TBS (iTBS) protocol in a randomized order. Altogether 6 sessions of stimulation were completed by each subject. Prior to and right after each stimulation session each participant performed an fMRI Stroop task a resting state fMRI measurement in 3T Siemens Prisma. Results: The reaction times (RTs) of incongruent stimuli were generally longer than the RTs of congruent stimuli across all conditions. Using paired sample t-test we have seen that after stimulation of IFG using iTBS subjects improved (decrease in RTs) in congruent condition (from 403.6 ms ± 88.8 to 396.4 ms ± 68.3) more than in incongruent one (from 409.4 ms ± 82.7 to 406.1 ms ± 71.9; p ¼ 0.014). Discussion: Our results reveal that iTBS over the right IFG may improve the cognitive speed especially in easier congruent condition in healthy young subjects. We plan to look at the imaging data and analyse the pre- to post- stimulation changes in the fMRI Stroop task and also resting state fMRI protocols. Keywords: theta burst stimulation, cognitive functions, functional magnetic resonance imaging, Stroop task
Introduction: Repetitive Transcranial Magnetic Stimulation (rTMS) is an emerging novel treatment being used for a variety of psychiatric and neurological disorders. It has been studied extensively in Major Depressive Disorder (MDD) but only a few studies have been conducted on Bipolar Depressive Disorder (BDD) patients. Methods: We conducted retrospective chart review of BDD patients at an urban TMS clinic. These patients received TMS as an adjunct treatment after they had failed treatment with multiple medications e antidepressants, mood stabilizers and psychotherapy. TMS targets were left and right dorsolateral prefrontal cortex (DLPFC). 14 patients received TMS treatment on left DLPFC at 120% MT, 10Hz, 3000 pulses and 26 patients received treatment on right DLPFC at 1 Hz, 2000 pulses. 22 patients received left sided high frequency treatment initially but were later switched to right side low frequency treatment. 16 patients received bilateral treatment with both left sided high frequency and right sided low frequency TMS. Results: A total of 78 BDD patients (mean age ¼ 47.2 years; 39 males and 39 females) were included in the analysis. 10 patients had Bipolar I, 35 had Bipolar II and 33 patients had Bipolar NOS. Patients received an average of 30 sessions. Montgomery-Asberg Depression Scale (MADRS) scores decreased an average of 21.2 points before (average MADRS score ¼ 33.3) and after (average MADRS score ¼ 12.1) the TMS treatments. All the patients tolerated the treatment well and there were no serious adverse events in any patient that were reported. Discussion: In this chart review we demonstrate that TMS was effective and safe for successful treatment of bipolar depressive symptoms in BDD patients. All the patients tolerated the treatment well with no severe adverse side effects. Larger randomized double blind sham controlled trials are needed to provide further data on its efficacy. Keywords: bipolar depressive disorder
[0551] BRAIN STIMULATION AND RECORDING WITH ULTRA-FLEXIBLE PEDOTCNT-COATED MICRO-ECOG ELECTRODE ARRAYS L. Pazzini*1, D. Polese 1, L. Maiolo 1, E. Castagnola 2, E. Maggiolini 2, E. Zucchini 2, M. Marrani 1, G. Fortunato 1, L. Fadiga 2, 3, D. Ricci 2. 1 IMM-CNR, Italy; 2 CTNS@UniFe, Istituto Italiano di Tecnologia, Italy; 3 University of Ferrara, Italy Introduction: To understand the cortical organization and the underlying brain computational principles, experiments based on simultaneous stimulation and recording from electrode arrays are a straightforward approach. Nevertheless, several technological problems need to be solved in order to be able to implement complex experimental protocols: spatial and temporal recording accuracy, noise, latency, compatibility, signal transmission and material durability. In this work, we propose a novel complete system for electrocorticography (ECoG) applications able to perform local recording and stimulation. Methods: High-density polyimide-based ECoG MEAs with submillimetre recording/stimulation sites were micro-fabricated, using electrodeposited PEDOT-CNT as neural interface material. To manage recording and stimulation, an ad-hoc electronics is introduced. The system is able to acquire, filter and digitalize the signals, perform signal processing algorithms and produce,
2
NYU Langone Medical
[0554] EFFECTS OF PROPRANOLOL ON CORTICAL EXCITABILITY: A TMS STUDY n 1. 1 Hospital General A. Miguel-Puga*1, 2, G. Villafuerte 1, 2, O. Arias-Carrio Dr Manuel Gea Gonzalez, Mexico; 2 Universidad Nacional Autonoma de Mexico, Mexico Introduction: Transcranial magnetic stimulation (TMS) is a well-established tool to explore the effects of drugs on different measurements of human cortical excitability. Propranolol is an unspecific beta adrenergic blocker that has the capability to cross the blood brain barrier and therefore, to act on the central nervous system. However, its effects have not been completely studied yet. Propranolol's clinical effectiveness on the control of migraine and essential tremor implies potential effects on central nervous system. Here, we explored the effects of propranolol over cortical excitability parameters in a TMS pilot study.
Abstracts / Brain Stimulation 10 (2017) 346e540
Methods: We designed a randomized, double blind, placebo controlled, cross over study. We recruited 6 healthy subjects (non smokers, without known central nervous disease and non-consumers of central nervous related drugs). After taking written informed consent, we measured cortical excitability parameters (motor threshold, latency, motor evocated potential (MEP) amplitude, MEP duration, cortical induced silent period (CSP) and recruitment curves). Afterwards, propranolol or placebo was administered and measurements were repeated at 2, 4, 6 and 8 hours. Clearance time between drugs was at least 1 week. After a clearance time of 1 week, proceedings were repeated. Results: Subjects (3 male, 3 female) had a mean age of 23.66±2.94 years. We found no significant differences between propranolol and placebo groups for motor threshold, latency, MEP amplitude, CSP and recruitment curves. Statistical analysis by mixed ANOVA indicated a significant group x time interaction for MEP duration (F4,40¼5.212, p¼0.006) and significant differences for all hours after baseline (with subsidiary ANOVA). Discussion: Propranolol increased the MEP duration, which can be associated with less intracortical inhibition of motor activity. The small size of the sample may have influenced the non significant differences on other cortical excitability parameters. Keywords: Transcranial magnetic stimulation, Propranolol, Cortical excitability [0555] SCALP-BASED HEURISTICS FOR LOCATING THE NODES OF THE SALIENCE NETWORK FOR USE IN NEUROSTIMULATION A. Mir-Moghtadaei 1, K. Dunlop 1, F. Mansouri 2, P. Giacobbe 3, S.H. Kennedy 1, 3, R.H. Lam 4, F. Vila-Rodriguez 4, Z.J. Daskalakis 1, 3, D.M. Blumberger 1,3, J. Downar*1,3. 1 Institute of Medical Sciences, Canada; 2 Institute of Biomaterials and Biomedical Engineering, Canada; 3 University Health Network, Canada; 4 University of British Columbia, Canada Introduction: The nodes of the Salience Network (SN) present potential therapeutic targets for non-invasive brain stimulation. For SN nodes in dorsolateral and dorsomedial prefrontal cortex (DLPFC, DMPFC), scalpbased heuristics were recently validated against MRI-guided neuronavigation. However, other SN nodes in anterior insula and inferior parietal lobule await validated scalp-based heuristics. Methods: We used resting-state fMRI from 303 MDD patients obtained prior to rTMS, and performed independent components analysis to identify SN node peak coordinates for left and right DLPFC, DMPFC, anterior insula, and inferior parietal lobule. We then located the scalp point closest to the peak coordinate for each node peak. Finally, we developed empirical heuristics for locating each point using the 3 cardinal scalp measurements of the 10-20 EEG system. Results: The DMPFC scalp site was at 31.16% of the Nasion-Inion (NI) line measuring from the nasion posteriorly. The right and left DLPFC were at 28.72% and 26.46% of the length of a line from Cz to the head circumference (HC) at 9.95% and 12.46% of the HC size, measured from Fpz to the right and left respectively. The right and left inferior parietal lobule (IPL) were at 29.88% and 30.25% of the length of a line originating at Cz and intersecting the HC at 19.39% and 18.91% of the HC from Oz to the right and left respectively. The right and left anterior insula (AI) were at 36.08% and 35.89% of the distance along a line originating at Cz and intersecting the HC at 18.68% and 19.40% of the HC from Fpz to the right and left respectively. Discussion: The empirically derived scalp-based heuristics for these SN nodes may facilitate future rTMS studies targeting these nodes for therapeutic purposes, in settings where it is infeasible to perform MRI-guided neuronavigation in all subjects. Keywords: Salience Network, Transcranial Magnetic Stimulation, Neuronavigation, Scalp [0558] VENTRAL MEDIAL PREFRONTAL CORTEX THETA BURST STIMULATION DECREASES SALIENCE NETWORK ACTIVITY IN COCAINE USERS AND ALCOHOL USERS C. Hanlon*, L. Dowdle, R. Anton, M. George. Medical University of South Carolina, USA
479
Background: Preclinical research has established that attenuating activity in the ventral striatum can decrease cocaine self-administration. Clinical neuroscientists are now attempting to translate those data to a neural circuit-based intervention for substance dependence, through non-invasive brain stimulation (NIBS). The goal of this study was to determine if continuous theta burst stimulation (cTBS; an attenuating form of NIBS) to the medial prefrontal cortex (mPFC) could reliably decrease frontal-striatal connectivity in cocaine-dependent and alcohol-dependent individuals. Methods: Fifty participants were enrolled in this single-blind, shamcontrolled, crossover study (25 cocaine dependent, 25 alcohol dependent). Frontal-striatal connectivity was measured with multimodal interleaved TMS/BOLD imaging immediately before and after 6 sessions of cTBS (110% resting motor threshold, FP1 location, 6 sessions/day). The effects of real versus sham cTBS on BOLD response to single pulses of TMS were measured for both groups (full factorial, scalp-to-cortex distance covariate, false discovery rate-corrected clusters reported, p<0.05) Results: Among cocaine users, real cTBS induced a significant decrease in bilateral BOLD response in mPFC, medial temporal gyrus, and precentral gyrus. Relative to sham, real cTBS induced a significant decrease in BOLD response in anterior cingulate cortex, mPFC, and temporal pole. Among alcohol users, real cTBS induced a significant decrease in BOLD response in left mPFC and middle temporal gyrus. Relative to sham, real cTBS induced a significant decrease in BOLD response in left mPFC, temporal pole, and parahippocampal gyrus. There was no significant effect of sham cTBS on BOLD response in any brain region. The brain response, as measured by BOLD activity, to real versus sham cTBS was not significantly different between cocaine and alcohol users. Conclusions: These data suggest that 6 sessions of mPFC cTBS delivered in a single day reliably decreases BOLD response to single pulses of TMS in the mPFC, anterior insula, and parahippocampal gyrusdall regions monosynaptically connected to one another, which regulate salience and limbic tone. The reliability of this pattern across cocaine- and alcohol-dependent individuals suggests that this may be an effective treatment target for multiple substance-dependent populations postulated to have dysregulated connectivity between infralimbic and cortical brain regions. Effects of TBS on cognitive control and reward responsivity in substance abusing populations needs to be evaluated. Keywords: interleaved TMS, alcohol, cocaine, theta burst stimulation [0559] ENHANCEMENT OF PROCESSING SPEED AND FRUSTRATION TOLERANCE WITH ANODAL TDCS C. Plewnia*. University of Tübingen, Germany Introduction: Deficits in executive functions, particularly in the control of attention, memory and information processing is critical for various psychiatric disorders. Effects of transcranial direct current stimulation (tDCS) on these functions have been demonstrated but the findings are still inconsistent. More detailed investigation and a better understanding of the mechanisms could be useful to guide the development of new treatment approaches. We have recently provided first evidence for an improved cognitive control over negative external stimuli (Plewnia et al. Lancet Psychiatry 2015;2:351) and task-induced negative emotions by anodal electric stimulation of the left dlPFC (Plewnia et al. PLoSOne 2015;10:e0122578). Methods and Results: To strengthen the evidence for a malleability of cognitive control on distractive negative information and the beneficial effects of tDCS on the training of these functions, two complementary experiments were performed. First. we reproduced our previous results in a more challenging adaptive 2-back Paced Auditory Serial Addition Task (PASAT) by demonstrating a facilitatory effect of concurrent anodal tDCS (1mA) to the left dorsolateral prefrontal cortex (n¼22) on processing speed in healthy young subjects. Most importantly, the increase of negative and the decrease of positive affects observed after the task with sham stimulation differed from active tDCS where no affective change was detected. Second, we tested the effect of anodal and cathodal tDCS to the left dlPFC concurrent to a 6-sessions 2-back PASAT training in a sham-controlled parallel-group study (n¼45) and observed an increased learning curve under anodal as compared to cathodal and sham stimulation. However, in this training trial, the effects on the affective state were less conclusive.
Abstracts / Brain Stimulation 10 (2017) 346e540
distribution in an attempt to characterise variance in tDCS response. To better quantify the interindividual variability rooted in anatomical differences, we used finite-element modelling (SimNIBS software package; Thielscher, Antunes, & Saturnino, 2015) to calculate individual current distribution based on participant-specific T1- and T2-weighted structural MRI scans. We adapted a psychophysical visual perimetry task in order to reduce participant performance to a single metric and measured the behavioural performance of young, healthy participants while anodal, cathodal and sham tDCS was applied to the visual cortex. Contrast sensitivity was then assessed at multiple visual field positions before, during and after tDCS. Thus, the present study relates the findings from individual electric field modelling to behavioural results obtained in the same participants. Future implications for the development of dose-dependent approaches to transcranial electrical stimulation are discussed. Keywords: transcranial direct current stimulation, visual cortex, finiteelement modelling, contrast sensitivity
on the selected electrode, an appropriate stimulation output in real time. Thus, the device is able to perform closed loop algorithms on local electrodes. Results: The ECoG MEAs have a total device thickness as low as 6 mm and adhere tightly to the brain surface. The PEDOT-CNT coating has very low impedance (7.2±2.2 kU @ 100Hz for 50mm diameter electrodes), allowing high signal to noise ratio signal recording. It also shows high charge transfer capability (>30mC/cm2), enabling high current density stimulation on ultrathin polymeric supports without delamination. The electronic board allows to record up to 32 channels at a maximum sampling rate of 1 MSample/s shared on the selected inputs or inject up to 2 mA current through the electrodes. Finally, the synergy of recording and stimulation on a single board allows the implementation of low latency closed loop algorithm (<500 ms). Discussion: The presented stimulation/recording platform is a powerful and flexible tool for brain-computer interfaces for clinical applications. Keywords: ECoG, PEDOT-CNT, MEA, closed-loop
[0548] THE INFLUENCE OF THETA BURST STIMULATION ON COGNITIVE FUNCTIONS AS ASSESSED BY FMRI STROOP TASK
[0552] SUCCESSFUL TREATMENT OF BIPOLAR DEPRESSIVE DISORDER PATIENTS USING TRANSCRANIAL MAGNETIC STIMULATION: RESULTS FROM AN URBAN TMS CLINIC
L. Anderkova*, M. Gajdos, E. Koritakova, I. Rektorova. Masaryk University, Czech Republic
R. McMullen*, S. Agarwal. 1 TMS Brain Care, USA; Center, USA
Introduction: The aim of this study was to investigate the effects of theta burst stimulation (TBS) on cognitive functions as assessed by fMRI Stroop task. Methods: Twelve healthy young subjects participated in the TBS-fMRI study. Each participant received a session of stimulation of the right inferior frontal gyrus (IFG), the left superior parietal lobule (SPL), and the vertex (VTX) using continuous TBS (cTBS) or intermittent TBS (iTBS) protocol in a randomized order. Altogether 6 sessions of stimulation were completed by each subject. Prior to and right after each stimulation session each participant performed an fMRI Stroop task a resting state fMRI measurement in 3T Siemens Prisma. Results: The reaction times (RTs) of incongruent stimuli were generally longer than the RTs of congruent stimuli across all conditions. Using paired sample t-test we have seen that after stimulation of IFG using iTBS subjects improved (decrease in RTs) in congruent condition (from 403.6 ms ± 88.8 to 396.4 ms ± 68.3) more than in incongruent one (from 409.4 ms ± 82.7 to 406.1 ms ± 71.9; p ¼ 0.014). Discussion: Our results reveal that iTBS over the right IFG may improve the cognitive speed especially in easier congruent condition in healthy young subjects. We plan to look at the imaging data and analyse the pre- to post- stimulation changes in the fMRI Stroop task and also resting state fMRI protocols. Keywords: theta burst stimulation, cognitive functions, functional magnetic resonance imaging, Stroop task
Introduction: Repetitive Transcranial Magnetic Stimulation (rTMS) is an emerging novel treatment being used for a variety of psychiatric and neurological disorders. It has been studied extensively in Major Depressive Disorder (MDD) but only a few studies have been conducted on Bipolar Depressive Disorder (BDD) patients. Methods: We conducted retrospective chart review of BDD patients at an urban TMS clinic. These patients received TMS as an adjunct treatment after they had failed treatment with multiple medications e antidepressants, mood stabilizers and psychotherapy. TMS targets were left and right dorsolateral prefrontal cortex (DLPFC). 14 patients received TMS treatment on left DLPFC at 120% MT, 10Hz, 3000 pulses and 26 patients received treatment on right DLPFC at 1 Hz, 2000 pulses. 22 patients received left sided high frequency treatment initially but were later switched to right side low frequency treatment. 16 patients received bilateral treatment with both left sided high frequency and right sided low frequency TMS. Results: A total of 78 BDD patients (mean age ¼ 47.2 years; 39 males and 39 females) were included in the analysis. 10 patients had Bipolar I, 35 had Bipolar II and 33 patients had Bipolar NOS. Patients received an average of 30 sessions. Montgomery-Asberg Depression Scale (MADRS) scores decreased an average of 21.2 points before (average MADRS score ¼ 33.3) and after (average MADRS score ¼ 12.1) the TMS treatments. All the patients tolerated the treatment well and there were no serious adverse events in any patient that were reported. Discussion: In this chart review we demonstrate that TMS was effective and safe for successful treatment of bipolar depressive symptoms in BDD patients. All the patients tolerated the treatment well with no severe adverse side effects. Larger randomized double blind sham controlled trials are needed to provide further data on its efficacy. Keywords: bipolar depressive disorder
[0551] BRAIN STIMULATION AND RECORDING WITH ULTRA-FLEXIBLE PEDOTCNT-COATED MICRO-ECOG ELECTRODE ARRAYS L. Pazzini*1, D. Polese 1, L. Maiolo 1, E. Castagnola 2, E. Maggiolini 2, E. Zucchini 2, M. Marrani 1, G. Fortunato 1, L. Fadiga 2, 3, D. Ricci 2. 1 IMM-CNR, Italy; 2 CTNS@UniFe, Istituto Italiano di Tecnologia, Italy; 3 University of Ferrara, Italy Introduction: To understand the cortical organization and the underlying brain computational principles, experiments based on simultaneous stimulation and recording from electrode arrays are a straightforward approach. Nevertheless, several technological problems need to be solved in order to be able to implement complex experimental protocols: spatial and temporal recording accuracy, noise, latency, compatibility, signal transmission and material durability. In this work, we propose a novel complete system for electrocorticography (ECoG) applications able to perform local recording and stimulation. Methods: High-density polyimide-based ECoG MEAs with submillimetre recording/stimulation sites were micro-fabricated, using electrodeposited PEDOT-CNT as neural interface material. To manage recording and stimulation, an ad-hoc electronics is introduced. The system is able to acquire, filter and digitalize the signals, perform signal processing algorithms and produce,
2
NYU Langone Medical
[0554] EFFECTS OF PROPRANOLOL ON CORTICAL EXCITABILITY: A TMS STUDY n 1. 1 Hospital General A. Miguel-Puga*1, 2, G. Villafuerte 1, 2, O. Arias-Carrio Dr Manuel Gea Gonzalez, Mexico; 2 Universidad Nacional Autonoma de Mexico, Mexico Introduction: Transcranial magnetic stimulation (TMS) is a well-established tool to explore the effects of drugs on different measurements of human cortical excitability. Propranolol is an unspecific beta adrenergic blocker that has the capability to cross the blood brain barrier and therefore, to act on the central nervous system. However, its effects have not been completely studied yet. Propranolol's clinical effectiveness on the control of migraine and essential tremor implies potential effects on central nervous system. Here, we explored the effects of propranolol over cortical excitability parameters in a TMS pilot study.
Abstracts / Brain Stimulation 10 (2017) 346e540
Methods: We designed a randomized, double blind, placebo controlled, cross over study. We recruited 6 healthy subjects (non smokers, without known central nervous disease and non-consumers of central nervous related drugs). After taking written informed consent, we measured cortical excitability parameters (motor threshold, latency, motor evocated potential (MEP) amplitude, MEP duration, cortical induced silent period (CSP) and recruitment curves). Afterwards, propranolol or placebo was administered and measurements were repeated at 2, 4, 6 and 8 hours. Clearance time between drugs was at least 1 week. After a clearance time of 1 week, proceedings were repeated. Results: Subjects (3 male, 3 female) had a mean age of 23.66±2.94 years. We found no significant differences between propranolol and placebo groups for motor threshold, latency, MEP amplitude, CSP and recruitment curves. Statistical analysis by mixed ANOVA indicated a significant group x time interaction for MEP duration (F4,40¼5.212, p¼0.006) and significant differences for all hours after baseline (with subsidiary ANOVA). Discussion: Propranolol increased the MEP duration, which can be associated with less intracortical inhibition of motor activity. The small size of the sample may have influenced the non significant differences on other cortical excitability parameters. Keywords: Transcranial magnetic stimulation, Propranolol, Cortical excitability [0555] SCALP-BASED HEURISTICS FOR LOCATING THE NODES OF THE SALIENCE NETWORK FOR USE IN NEUROSTIMULATION A. Mir-Moghtadaei 1, K. Dunlop 1, F. Mansouri 2, P. Giacobbe 3, S.H. Kennedy 1, 3, R.H. Lam 4, F. Vila-Rodriguez 4, Z.J. Daskalakis 1, 3, D.M. Blumberger 1,3, J. Downar*1,3. 1 Institute of Medical Sciences, Canada; 2 Institute of Biomaterials and Biomedical Engineering, Canada; 3 University Health Network, Canada; 4 University of British Columbia, Canada Introduction: The nodes of the Salience Network (SN) present potential therapeutic targets for non-invasive brain stimulation. For SN nodes in dorsolateral and dorsomedial prefrontal cortex (DLPFC, DMPFC), scalpbased heuristics were recently validated against MRI-guided neuronavigation. However, other SN nodes in anterior insula and inferior parietal lobule await validated scalp-based heuristics. Methods: We used resting-state fMRI from 303 MDD patients obtained prior to rTMS, and performed independent components analysis to identify SN node peak coordinates for left and right DLPFC, DMPFC, anterior insula, and inferior parietal lobule. We then located the scalp point closest to the peak coordinate for each node peak. Finally, we developed empirical heuristics for locating each point using the 3 cardinal scalp measurements of the 10-20 EEG system. Results: The DMPFC scalp site was at 31.16% of the Nasion-Inion (NI) line measuring from the nasion posteriorly. The right and left DLPFC were at 28.72% and 26.46% of the length of a line from Cz to the head circumference (HC) at 9.95% and 12.46% of the HC size, measured from Fpz to the right and left respectively. The right and left inferior parietal lobule (IPL) were at 29.88% and 30.25% of the length of a line originating at Cz and intersecting the HC at 19.39% and 18.91% of the HC from Oz to the right and left respectively. The right and left anterior insula (AI) were at 36.08% and 35.89% of the distance along a line originating at Cz and intersecting the HC at 18.68% and 19.40% of the HC from Fpz to the right and left respectively. Discussion: The empirically derived scalp-based heuristics for these SN nodes may facilitate future rTMS studies targeting these nodes for therapeutic purposes, in settings where it is infeasible to perform MRI-guided neuronavigation in all subjects. Keywords: Salience Network, Transcranial Magnetic Stimulation, Neuronavigation, Scalp [0558] VENTRAL MEDIAL PREFRONTAL CORTEX THETA BURST STIMULATION DECREASES SALIENCE NETWORK ACTIVITY IN COCAINE USERS AND ALCOHOL USERS C. Hanlon*, L. Dowdle, R. Anton, M. George. Medical University of South Carolina, USA
479
Background: Preclinical research has established that attenuating activity in the ventral striatum can decrease cocaine self-administration. Clinical neuroscientists are now attempting to translate those data to a neural circuit-based intervention for substance dependence, through non-invasive brain stimulation (NIBS). The goal of this study was to determine if continuous theta burst stimulation (cTBS; an attenuating form of NIBS) to the medial prefrontal cortex (mPFC) could reliably decrease frontal-striatal connectivity in cocaine-dependent and alcohol-dependent individuals. Methods: Fifty participants were enrolled in this single-blind, shamcontrolled, crossover study (25 cocaine dependent, 25 alcohol dependent). Frontal-striatal connectivity was measured with multimodal interleaved TMS/BOLD imaging immediately before and after 6 sessions of cTBS (110% resting motor threshold, FP1 location, 6 sessions/day). The effects of real versus sham cTBS on BOLD response to single pulses of TMS were measured for both groups (full factorial, scalp-to-cortex distance covariate, false discovery rate-corrected clusters reported, p<0.05) Results: Among cocaine users, real cTBS induced a significant decrease in bilateral BOLD response in mPFC, medial temporal gyrus, and precentral gyrus. Relative to sham, real cTBS induced a significant decrease in BOLD response in anterior cingulate cortex, mPFC, and temporal pole. Among alcohol users, real cTBS induced a significant decrease in BOLD response in left mPFC and middle temporal gyrus. Relative to sham, real cTBS induced a significant decrease in BOLD response in left mPFC, temporal pole, and parahippocampal gyrus. There was no significant effect of sham cTBS on BOLD response in any brain region. The brain response, as measured by BOLD activity, to real versus sham cTBS was not significantly different between cocaine and alcohol users. Conclusions: These data suggest that 6 sessions of mPFC cTBS delivered in a single day reliably decreases BOLD response to single pulses of TMS in the mPFC, anterior insula, and parahippocampal gyrusdall regions monosynaptically connected to one another, which regulate salience and limbic tone. The reliability of this pattern across cocaine- and alcohol-dependent individuals suggests that this may be an effective treatment target for multiple substance-dependent populations postulated to have dysregulated connectivity between infralimbic and cortical brain regions. Effects of TBS on cognitive control and reward responsivity in substance abusing populations needs to be evaluated. Keywords: interleaved TMS, alcohol, cocaine, theta burst stimulation [0559] ENHANCEMENT OF PROCESSING SPEED AND FRUSTRATION TOLERANCE WITH ANODAL TDCS C. Plewnia*. University of Tübingen, Germany Introduction: Deficits in executive functions, particularly in the control of attention, memory and information processing is critical for various psychiatric disorders. Effects of transcranial direct current stimulation (tDCS) on these functions have been demonstrated but the findings are still inconsistent. More detailed investigation and a better understanding of the mechanisms could be useful to guide the development of new treatment approaches. We have recently provided first evidence for an improved cognitive control over negative external stimuli (Plewnia et al. Lancet Psychiatry 2015;2:351) and task-induced negative emotions by anodal electric stimulation of the left dlPFC (Plewnia et al. PLoSOne 2015;10:e0122578). Methods and Results: To strengthen the evidence for a malleability of cognitive control on distractive negative information and the beneficial effects of tDCS on the training of these functions, two complementary experiments were performed. First. we reproduced our previous results in a more challenging adaptive 2-back Paced Auditory Serial Addition Task (PASAT) by demonstrating a facilitatory effect of concurrent anodal tDCS (1mA) to the left dorsolateral prefrontal cortex (n¼22) on processing speed in healthy young subjects. Most importantly, the increase of negative and the decrease of positive affects observed after the task with sham stimulation differed from active tDCS where no affective change was detected. Second, we tested the effect of anodal and cathodal tDCS to the left dlPFC concurrent to a 6-sessions 2-back PASAT training in a sham-controlled parallel-group study (n¼45) and observed an increased learning curve under anodal as compared to cathodal and sham stimulation. However, in this training trial, the effects on the affective state were less conclusive.