Grosshagauer, S.

Linhardt, D.

Nohava, L.

Schuler, A. 

Tik, M.

Vasileiadi, M.

Williams, N.

Windischberger, C.

Woletz, M.

English

MPG.PuRe

Abstracts Brain Stimulation 18 (2025) 208e617However, its neurophysiological effects on functional recovery remainlargely unexplored, which forms the primary aim of the current study.MethodsThe study included eight patients with Unresponsive Wakefulness Syn-drome (UWS) and twelve patients with Minimally Conscious State (MCS).Initial assessments were conducted using the Coma Recovery Scale-Revised (CRS-R) and electroencephalographic recordings during an audi-tory oddball paradigm to detect MMN and P300 components, as well astheir oscillatory characteristics. Participants received forty 30-minutetaVNS sessions twice daily for an average of 30±4 days, followed by a CRS-R and electroencephalographic reassessment. A control group of six UWSand three MCS patients underwent identical assessments withoutstimulation.ResultsCRS-R improvements following taVNS were observed exclusively in MCS.Moreover, an increase in MMN amplitude was observed in the MCSfollowing taVNS. This effect was also reflected in the spectral character-istics of the MMN component, including alterations in total power and inDelta and Theta modulation. Regarding the P300 component, an increasein amplitude was also detected for the MCS after taVNS. In addition, al-terations in Alpha and Beta modulation of the P300 component were alsodetected after stimulation.DiscussionThe findings suggest that taVNS may facilitate the recovery of specificexecutive and attentional functions in MCS, aligning with previous studiesusing other non-invasive techniques like tDCS. These results could beattributed to preserved neural substrates and suggest that taVNS mayregulate the Default Mode Network and the External Fronto-ParietalNetwork. However, the study has limitations, including a small controlgroup and a lack of follow-up. Further research is needed to determine thephysiological effects of taVNS in DoCs patients, in order to provide themwith accurate care and treatment.Research Category and Technology and MethodsClinical Research: 12. Vagus Nerve Stimulation (VNS)KeywordsDisorders of Consciousness (DoCs), Cognitive evoked potentials, Trans-auricular Vagus Nerve Stimulation (taVNS), Waveletshttp://dx.doi.org/10.1016/j.brs.2024.12.622P1.184E-FIELD-GUIDED INTENSITY ADJUSTMENT FOR MOTIONCOMPENSATION IN CONCURRENT TMS-FMRISarah Grosshagauer 1, Michael Woletz 1, Dominik Zeman 1,2, AnjaRejc 1,2, Bernardo Campilho 1, Dominik Zuschlag 1,3, DavidLinhardt 1, Martin Tik 1,4, Christian Windischberger 1. 1Center for MedicalPhysics and Biomedical Engineering, Medical University of Vienna, Austria;2University of Vienna, Austria; 3 Technical University of Vienna, Austria;4Department of Psychiatry and Behavioral Sciences, Stanford University, USAAbstractSubject motion is a significant challenge in concurrent TMS-fMRI, as it canimpact stimulation location and intensity. While previous motion-compensation techniques primarily focus on coil-cortex distance, coilrotation and tilt also significantly influence the induced electric field (E-field). To address these issues, we developed a framework for online in-tensity adjustment based on a-priori E-field simulations to compensate formotion-induced changes in coil position.Our framework integrates real-time motion tracking with precomputed E-field simulations, considering various positions and coil orientations usingSimNIBS 4.0.0. Coil and subject tracking are performed using an NDI Polariscamera and retroreflective trackers mounted on coil and a mouthpieceattached to the participant. Using Python-tools the estimated E-field in thetarget region is interpolated from pre-computed simulations and TMSamplitude is adjusted accordingly. In pilot experiments, we applied thisnovel approach in volunteers during TMS/fMRI targeting the hand knob ofthe primary motor cortex. Measurements were conducted on a 3T SiemensPrisma Fit scanner using dedicated surface-coil-arrays and an MR-compatible TMS coil. The TMS coil was positioned near the optimal425position according to SimNIBS optimization. Stimulationwas performed inblocks of 5 pulses (1 Hz), separated by 30 seconds, aiming for 100% rMTwith or without E-field-guided adjustments in two subsequent runs. Tosimulate exaggerated movement, the participant was asked to move atspecific timepoints between blocks.Our approach allowed us to successfully use motion tracking for stimula-tion intensity adjustment during TMS-fMRI. Consistent engagement of M1despite excessive motion was validated by BOLD activation in the targetedarea, which was absent in the non-adjusted run.This demonstrates that real-time E-field-guided intensity adjustments cancompensate for the stimulation intensity reduction at the target locationfrom subject motion during TMS-fMRI, enhancing the reliability of TMSprotocols and making it a valuable tool for concurrent TMS-fMRI.ĂResearch Category and Technology and MethodsBasic Research: 10. Transcranial Magnetic Stimulation (TMS)KeywordsTranscranial Magnetic Stimulation, Motion Tracking, Electric FieldModelling, Concurrent TMS-fMRIhttp://dx.doi.org/10.1016/j.brs.2024.12.623P1.185CHRONOMETRIC TMS-FMRI FOR EXPLORING WHOLE-BRAIN STATE-DEPENDENT EFFECTS OF DLPFC STIMULATIONSarah Grosshagauer 1, Michael Woletz 1, Maria Vasileiadi 1, DavidLinhardt 1, Lena Nohava 1, Anna-Lisa Schuler 2, ChristianWindischberger 1, Nolan Williams 3, Martin Tik 1,3. 1Center for MedicalPhysics and Biomedical Engineering, Medical University of Vienna, Austria;2Max Planck Institute for Human Cognitive and Brain Sciences, Germany;3Department for Psychiatry and Behavioral Sciences, Stanford University,USAAbstractTranscranial magnetic stimulation (TMS) to the left dorsolateral prefrontalcortex (DLPFC) is a highly effective treatment option for major depressivedisorder. Recently, the individualization of targets based on functionalconnectivity to the subgenual anterior cingulate cortex (sgACC) has beendefined as a major aspect in increasing treatment effectiveness. However,among therapy plans and individuals, variability in TMS efficacy still re-mains a significant challenge. One aspect which might contribute to thisbut is currently not considered in clinical treatments is the underlyingbrain state. Therefore, we applied interleaved TMS-fMRI to the DLPFCAbstracts Brain Stimulation 18 (2025) 208e617during rest and task to visualize the influence of brain state on TMS effectson a whole-brain level.Twenty healthy participants were included in this study. We employed anadvanced chronometric TMS-fMRI design stimulating individualized tar-gets in the left DLPFC (based on sgACC anti-correlation). 10 Hz triplets ofTMS were delivered either during rest or at precisely defined timepoints(in a chronometric fashion) during an N-back task during continuousimaging, allowing to interfere with different cognitive processes and thusunderlying brain states. Electric fields based on neuronavigation data werepost-hoc calculated for each participant and used to estimate the stimu-lated network, which was compared across participants as well as to thedetected BOLD response.Differential effects for only small changes in stimulation timing could bedetected in clinically relevant brain regions, most importantly the sgACC.Also, task-based stimulation showed higher consistency in sgACC activa-tion compared to TMS during rest.In conclusion, these results highlight the complexity of TMS interventions.Especially if TMS is applied to higher cognitive areas like the DLPFC,already small differences in stimulation timing can change how TMS af-fects deeper brain regions. Incorporating this knowledge into clinicalpractice could lead to more consistent and effective outcomes, potentiallyreducing the variability in TMS efficacy observed across individuals.Research Category and Technology and MethodsTranslational Research: 10. Transcranial Magnetic Stimulation (TMS)Keywordsinterleaved TMS-fMRI, brain state dependency, cognitive states, TMSdepression treatmenthttp://dx.doi.org/10.1016/j.brs.2024.12.624P1.186MULTI-POLAR TEMPORAL INTERFERENCE STIMULATION: COMPARINGELECTRIC FIELDS IN-SILICO VS IN-VIVO IN THE RHESUS MACAQUESarah Kearsley, Sebastian Lehmann, Lyle Muller, Brian Corneil. WesternUniversity, CanadaAbstractTemporal interference stimulation (TI) is a non-invasive stimulationtechnique that may be able to modulate neural activity in subcorticalstructures. During TI, two high-frequency (> 1kHz) carrier fields aredelivered, that on their own, do not recruit neural activity. These carrierfrequencies are offset by a small difference (the ‘envelope’). In a smallregion that depends on stimulation locations and intensities the interac-tion of the carrier fields creates an amplitude modulated waveform at theenvelope frequency that can influence neural activity. The focality andelectric field strengths achieved by TI can be increased by adding electricfields at different carrier frequencies that are offset by the same envelope(‘multi-polar TI’). Multi-polar TI is dependent on having the overlappingregions targeted by each envelope, highlighting the need for accurateelectric field estimations. While these fields can be estimated withcomputational modeling, whether the accuracy achieved with these sim-ulations are sufficient for accurate targeting needs to be verified. Weaddress this question through modelling the electric fields arising frommulti-polar TI in the macaque brain and comparing these simulated fieldsto electric fields recorded in vivo. We estimate the electric field strengthsusing finite-difference modelling in a personalized tissue-segmentedmodel of the experimental macaque in Sim4Life. For each electric field, weadjusted the current amplitude to target the region of interest. We chose totarget a cortical (frontal eye fields) and subcortical (superior colliculus)target. We found our simulations provided accurate estimations of thecortical and subcortical recorded electric fields in vivo. This work suggeststhat the simulations provide sufficient accuracy, bolstering the applicationof multi-polar TI as a feasible stimulation technique.Research Category and Technology and MethodsBasic Research: 5. Other Transcranial Electrical Stimulation (tES)KeywordsTemporal Interference Stimulation, Electric Field Simulation, Non-InvasiveBrain Stimulation, Rhesus Macaque426http://dx.doi.org/10.1016/j.brs.2024.12.625P1.187THE PROFILE OF SYMPTOM CHANGE WITH TRANSCRANIAL MAGNETICSTIMULATION FOR MAJOR DEPRESSIVE DISORDERTodd Hutton 1, Scott Aaronson 2, Linda Carpenter 3, KennethPages 4, Harold Sackeim 5. 1 Southern California TMS Center, Los Angeles,CA, USA; 2 Sheppard Pratt Health System, USA; 3Brown University WarrenAlpert Medical School, USA; 4 TMS of South Tampa, Tampa, FL, USA;5Medical University of South Carolina, USAAbstractBackground: Antidepressant treatments can differ in the depressivesymptoms least and most responsive. The profile of symptom change withTMS has yet to be characterized.Methods: The PHQ-9 and QIDS-SR were administered to 578 patients withMDD who scored 10 on both instruments at baseline and received 36TMS sessions. For both instruments, differences in severity among symp-toms were characterized before and following TMS. The extent to whichTMS produced a non-specific, generalized improvement across symptomsor a symptom-specific profile of improvement was evaluated.Results: Symptoms differed markedly in average severity at baseline, withthe profiles consistent across the two instruments. Comparisons ofsymptom severity before and after TMS produced very large main effectsof time (Pre vs Post) and inventory Item, but only small interaction effects,indicating limited symptom specificity in improvement. There was wide-spread improvement across symptoms, and the limited apparent symptomspecificity was largely due to floor effects resulting at baseline in specificsymptoms. Comparisons of three TMS protocols, Left Only, SequentialBilateral, and Mixture, revealed no differences in profile of symptomchange. Following TMS, the severity of residual symptoms in responderswho did not remit, while substantially improved, largely mirrored thebaseline profile.Conclusions: Treatment of depression with TMS results in a markeddownward shift of the baseline profile of symptom severity. There is large,generalized improvement across symptoms and limited symptomspecificity.Research Category and Technology and MethodsClinical Research: 10. Transcranial Magnetic Stimulation (TMS)KeywordsTMS, Depression, Symptom propfile, Effectivenesshttp://dx.doi.org/10.1016/j.brs.2024.12.626P1.188INVESTIGATING A TRUNCATED VERSION OF SAINT IN TREATMENT-NAIVE ADOLESCENTS WITH DEPRESSION: AN OPEN-LABELACCEPTABILITY TRIALSean O'Sullivan 1, Elyse Lemke 1, Trinh Ha 1, Arjun Srivastava 1, MicheleLaGrone 1,2, Grant Marshall 3, Katarina Jakimier 3, Ila Kamath 1, ManviMutyala 1, Charles Nemeroff 1. 1Dell Medical School at University of Texasat Austin, USA; 2Dell Children's Medical Center of Central Texas, USA; 3 TheUniversity of Texas at Austin, USAAbstractDeveloping novel treatments for adolescent depression is imperative asrates of adolescent depression have reached crisis levels while pharma-cotherapies with limited efficacy and an increased risk of suicidalityremain first-line. Stanford Accelerated Intelligent Neuromodulation Ther-apy (SAINT), an optimized form of transcranial magnetic stimulation(TMS), is FDA-cleared for treatment-resistant depression (TRD) in adults,and could support in ameliorating this crisis. SAINT, however, remainsunderstudied in adolescents and poses a considerable time commitmentas ten treatments are given per day. We are conducting a two-arm open-label trial investigating the safety, efficacy, and convenience of standardSAINT compared to a truncated version in antidepressant-free treatment-naive adolescents in their first major depressive episode. Truncated SAINT

Chronometric TMS-fMRI for exploring whole-brain state-dependent effects of DLPFC stimulation

http://hdl.handle.net/21.11116/0000-0010-D1BD-D

Chronometric TMS-fMRI for exploring whole-brain state-dependent effects of DLPFC stimulation

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