Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.013
Franz Roman Schmid, Julia Sophia Crone
{"title":"A shift towards more precision: Addressing the profound implications of brain shift in model-based planning for ultrasonic brain stimulation","authors":"Franz Roman Schmid, Julia Sophia Crone","doi":"10.1016/j.brs.2025.02.013","DOIUrl":"10.1016/j.brs.2025.02.013","url":null,"abstract":"","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 276-277"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143490755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.018
Xiwei She , Wendy Qi , Kerry C. Nix , Miguel Menchaca , Christopher C. Cline , Wei Wu , Zihuai He , Fiona M. Baumer
Objective
Self-limited epilepsy with centrotemporal spikes (SeLECTS) is a common pediatric syndrome in which interictal epileptiform discharges (IEDs) emerge from the motor cortex and children often develop language deficits. IEDs may induce these language deficits by pathologically enhancing brain connectivity. Using a sham-controlled design, we test the impact of inhibitory low-frequency repetitive transcranial magnetic stimulation (rTMS) on connectivity and IEDs in SeLECTS.
Methods
Nineteen children participated in a cross-over study comparing active vs. sham motor cortex rTMS. Single pulses of TMS combined with EEG (spTMS-EEG) were applied to the motor cortex before and after rTMS to probe connectivity. Connectivity was quantified by calculating the weighted phase lag index (wPLI) between six regions of interest: bilateral motor cortices (implicated in SeLECTS) and bilateral inferior frontal and superior temporal regions (important for language). IED frequency before and after rTMS was also quantified.
Results
Active, but not sham, rTMS decreased wPLI connectivity between multiple regions, with the greatest reductions seen in superior temporal connections in the stimulated hemisphere. IED frequency decreased after active but not sham rTMS.
Significance
Low-frequency rTMS reduces pathologic hyperconnectivity and IEDs in children with SeLECTS, making it a promising avenue for therapeutic interventions for SeLECTS and potentially other pediatric epilepsy syndromes.
{"title":"Repetitive transcranial magnetic stimulation modulates brain connectivity in children with self-limited epilepsy with centrotemporal spikes","authors":"Xiwei She , Wendy Qi , Kerry C. Nix , Miguel Menchaca , Christopher C. Cline , Wei Wu , Zihuai He , Fiona M. Baumer","doi":"10.1016/j.brs.2025.02.018","DOIUrl":"10.1016/j.brs.2025.02.018","url":null,"abstract":"<div><h3>Objective</h3><div>Self-limited epilepsy with centrotemporal spikes (SeLECTS) is a common pediatric syndrome in which interictal epileptiform discharges (IEDs) emerge from the motor cortex and children often develop language deficits. IEDs may induce these language deficits by pathologically enhancing brain connectivity. Using a sham-controlled design, we test the impact of inhibitory low-frequency repetitive transcranial magnetic stimulation (rTMS) on connectivity and IEDs in SeLECTS.</div></div><div><h3>Methods</h3><div>Nineteen children participated in a cross-over study comparing active vs. sham motor cortex rTMS. Single pulses of TMS combined with EEG (spTMS-EEG) were applied to the motor cortex before and after rTMS to probe connectivity. Connectivity was quantified by calculating the weighted phase lag index (wPLI) between six regions of interest: bilateral motor cortices (implicated in SeLECTS) and bilateral inferior frontal and superior temporal regions (important for language). IED frequency before and after rTMS was also quantified.</div></div><div><h3>Results</h3><div>Active, but not sham, rTMS decreased wPLI connectivity between multiple regions, with the greatest reductions seen in superior temporal connections in the stimulated hemisphere. IED frequency decreased after active but not sham rTMS.</div></div><div><h3>Significance</h3><div>Low-frequency rTMS reduces pathologic hyperconnectivity and IEDs in children with SeLECTS, making it a promising avenue for therapeutic interventions for SeLECTS and potentially other pediatric epilepsy syndromes.</div></div>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 287-297"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.014
Isha Vora , Baothy P. Huynh , David J. Lin , Teresa J. Kimberley
{"title":"MEP status revisited: Potential value of the MEP trichotomy to distinguish arm motor behavior","authors":"Isha Vora , Baothy P. Huynh , David J. Lin , Teresa J. Kimberley","doi":"10.1016/j.brs.2025.02.014","DOIUrl":"10.1016/j.brs.2025.02.014","url":null,"abstract":"","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 262-264"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143476324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.011
Daniel T. Corp , Hannah G.K. Bereznicki , Michael P. Barham , Gillian M. Clark , Benjamin J. Chadwick , Saksham Jain , Hourieh Khalajzadeh , Alvaro Pascual-Leone , Peter G. Enticott
{"title":"Big non-invasive brain stimulation data (Big NIBS data): An open-access platform and repository for NIBS data","authors":"Daniel T. Corp , Hannah G.K. Bereznicki , Michael P. Barham , Gillian M. Clark , Benjamin J. Chadwick , Saksham Jain , Hourieh Khalajzadeh , Alvaro Pascual-Leone , Peter G. Enticott","doi":"10.1016/j.brs.2025.02.011","DOIUrl":"10.1016/j.brs.2025.02.011","url":null,"abstract":"","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 278-279"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143476322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.012
Shan H. Siddiqi , Leo Chen , Nicholas T. Trapp , Noreen Bukhari-Parlakturk , Joseph J. Taylor , Aaron D. Boes , Joshua C. Brown , Tracy Barbour , Joan A. Camprodon , Michael D. Fox , Brian H. Kopell , Carlene MacMillan , Alfonso Fasano , Robert S. Fisher , Ziad Nahas , Gonzalo J. Revuelta , Patricio Riva-Posse , John D. Rolston , Katherine Scangos , Mouhsin M. Shafi , Nolan R. Williams
The rapid development and clinical use of brain stimulation has renewed debates about whether to define and accredit a pathway for clinical subspecialty training. To address this, the Brain Stimulation Subspecialty Summits (BraSSS) were convened in 2023 and 2024, featuring international leaders in brain stimulation across psychiatry, neurology, neurosurgery, psychology, and neuroscience. Both meetings included two days of lectures and debates focused on clinical content, emerging science, and educational standards. The 2023 meeting was held at Brigham & Women's Hospital and Harvard University, where 54 attendees reached a consensus that the subspecialty is adequately developed to warrant formal recognition and initiated debates regarding the name and scope of the subspecialty. The 2024 meeting was held at Stanford University, where 56 attendees developed a content outline, organized committees, and reached a consensus to form an independent society focused on developing and maintaining unbiased accreditation standards. “Brain stimulation” was chosen democratically as the name of the subspecialty. Clinicians from multiple primary specialties may enter this subspecialty training track. While individual programs may have a specific area of focus (e.g. interventional psychiatry or epilepsy), our expectation is that accredited brain stimulation programs will provide training experiences that cross specialties and stimulation modalities. Several potential unintended consequences were discussed, and plans were developed to address them. Overall, subspecialty recognition was deemed to be beneficial to the brain stimulation field, with a goal to launch an associated society and start the process of accrediting existing US and Canadian programs in 2025.
{"title":"Towards accredited clinical training in brain stimulation: Proceedings from the brain stimulation subspecialty summits","authors":"Shan H. Siddiqi , Leo Chen , Nicholas T. Trapp , Noreen Bukhari-Parlakturk , Joseph J. Taylor , Aaron D. Boes , Joshua C. Brown , Tracy Barbour , Joan A. Camprodon , Michael D. Fox , Brian H. Kopell , Carlene MacMillan , Alfonso Fasano , Robert S. Fisher , Ziad Nahas , Gonzalo J. Revuelta , Patricio Riva-Posse , John D. Rolston , Katherine Scangos , Mouhsin M. Shafi , Nolan R. Williams","doi":"10.1016/j.brs.2025.02.012","DOIUrl":"10.1016/j.brs.2025.02.012","url":null,"abstract":"<div><div>The rapid development and clinical use of brain stimulation has renewed debates about whether to define and accredit a pathway for clinical subspecialty training. To address this, the Brain Stimulation Subspecialty Summits (BraSSS) were convened in 2023 and 2024, featuring international leaders in brain stimulation across psychiatry, neurology, neurosurgery, psychology, and neuroscience. Both meetings included two days of lectures and debates focused on clinical content, emerging science, and educational standards. The 2023 meeting was held at Brigham & Women's Hospital and Harvard University, where 54 attendees reached a consensus that the subspecialty is adequately developed to warrant formal recognition and initiated debates regarding the name and scope of the subspecialty. The 2024 meeting was held at Stanford University, where 56 attendees developed a content outline, organized committees, and reached a consensus to form an independent society focused on developing and maintaining unbiased accreditation standards. “Brain stimulation” was chosen democratically as the name of the subspecialty. Clinicians from multiple primary specialties may enter this subspecialty training track. While individual programs may have a specific area of focus (e.g. interventional psychiatry or epilepsy), our expectation is that accredited brain stimulation programs will provide training experiences that cross specialties and stimulation modalities. Several potential unintended consequences were discussed, and plans were developed to address them. Overall, subspecialty recognition was deemed to be beneficial to the brain stimulation field, with a goal to launch an associated society and start the process of accrediting existing US and Canadian programs in 2025.</div></div>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 298-305"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143482145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.016
Wan-wa Wong , D. Rangaprakash , Joel P. Diaz-Fong , Hayden J. Peel , Reza Tadayonnejad , Andrew F. Leuchter , Jamie D. Feusner
{"title":"Effects of noninvasive neuromodulation combined with rapid, short-duration self-image stimuli in body dysmorphic disorder","authors":"Wan-wa Wong , D. Rangaprakash , Joel P. Diaz-Fong , Hayden J. Peel , Reza Tadayonnejad , Andrew F. Leuchter , Jamie D. Feusner","doi":"10.1016/j.brs.2025.02.016","DOIUrl":"10.1016/j.brs.2025.02.016","url":null,"abstract":"","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 259-261"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143490674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.015
Umair Hassan , Prince Okyere , Milad Amini Masouleh , Christoph Zrenner , Ulf Ziemann , Til Ole Bergmann
Thalamocortical sleep spindles, i.e., oscillatory bursts at ∼12–15 Hz of waxing and waning amplitude, are a hallmark feature of non-rapid eye movement (NREM) sleep and believed to play a key role in memory reactivation and consolidation. Generated in the thalamus and projecting to neocortex and hippocampus, they are phasically modulated by neocortical slow oscillations (<1 Hz) and in turn phasically modulate hippocampal sharp-wave ripples (>80 Hz). This hierarchical cross-frequency nesting, where slower oscillations group faster ones into certain excitability phases, may enable phase-dependent plasticity in the neocortex, and spindles have thus been considered windows of plasticity in the sleeping brain. However, the assumed phasic excitability modulation had not yet been demonstrated for spindles. Utilizing a recently developed real-time spindle detection algorithm, we applied spindle phase-triggered transcranial magnetic stimulation (TMS) to the primary motor cortex (M1) hand area to characterize the corticospinal excitability profile of spindles via motor evoked potentials (MEP). MEPs showed net suppression during spindles, driven by a “pulse of inhibition” during its falling flank with no inhibition or facilitation during its peak, rising flank, or trough. This unidirectional (“asymmetric”) modulation occurred on top of the general sleep-related inhibition during spindle-free NREM sleep and did not extend into the refractory post-spindle periods. We conclude that spindles exert “asymmetric pulsed inhibition" on corticospinal excitability. These findings and the developed real-time spindle targeting methods enable future studies to investigate the causal role of spindles in phase-dependent synaptic plasticity and systems memory consolidation during sleep by repetitively targeting relevant spindle phases.
{"title":"Pulsed inhibition of corticospinal excitability by the thalamocortical sleep spindle","authors":"Umair Hassan , Prince Okyere , Milad Amini Masouleh , Christoph Zrenner , Ulf Ziemann , Til Ole Bergmann","doi":"10.1016/j.brs.2025.02.015","DOIUrl":"10.1016/j.brs.2025.02.015","url":null,"abstract":"<div><div>Thalamocortical sleep spindles, i.e., oscillatory bursts at ∼12–15 Hz of waxing and waning amplitude, are a hallmark feature of non-rapid eye movement (NREM) sleep and believed to play a key role in memory reactivation and consolidation. Generated in the thalamus and projecting to neocortex and hippocampus, they are phasically modulated by neocortical slow oscillations (<1 Hz) and in turn phasically modulate hippocampal sharp-wave ripples (>80 Hz). This hierarchical cross-frequency nesting, where slower oscillations group faster ones into certain excitability phases, may enable phase-dependent plasticity in the neocortex, and spindles have thus been considered windows of plasticity in the sleeping brain. However, the assumed phasic excitability modulation had not yet been demonstrated for spindles. Utilizing a recently developed real-time spindle detection algorithm, we applied spindle phase-triggered transcranial magnetic stimulation (TMS) to the primary motor cortex (M1) hand area to characterize the corticospinal excitability profile of spindles via motor evoked potentials (MEP). MEPs showed net suppression during spindles, driven by a “pulse of inhibition” during its falling flank with no inhibition or facilitation during its peak, rising flank, or trough. This unidirectional (“asymmetric”) modulation occurred on top of the general sleep-related inhibition during spindle-free NREM sleep and did not extend into the refractory post-spindle periods. We conclude that spindles exert “asymmetric pulsed inhibition\" on corticospinal excitability. These findings and the developed real-time spindle targeting methods enable future studies to investigate the causal role of spindles in phase-dependent synaptic plasticity and systems memory consolidation during sleep by repetitively targeting relevant spindle phases.</div></div>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 265-275"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143476332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.021
Xin Li, Kenneth B Baker, Kyle O'Laughlin, Yin-Liang Lin, Kelsey Baker, Robert Chen, Jacqueline Chen, Andre G Machado, Ela B Plow
Background: Deep brain stimulation of the dentate nucleus (DN-DBS) is an emerging therapy to improve upper extremity (UE) motor function after stroke. This study sought to investigate the physiologic mechanisms of acute DN-DBS in chronic stroke survivors enrolled in a phase I trial for DN-DBS.
Methods: Twelve chronic stroke participants with moderate-to-severe UE impairment received (acute) single sessions (≥45 min) of active DBS and sham DBS in a sham-controlled, double-blind, cross-over experiment (order randomized). Transcranial magnetic stimulation (TMS) was used to evaluate corticomotor physiology. We also characterized the relationship between acute DBS effects on physiology and baseline clinical and neuroimaging measures, and chronic DBS effects on motor function.
Results: Acute active DBS led to an increase in ipsilesional corticomotor excitability evident as a 5.2% maximal stimulator output (MSO) reduction in active motor threshold (p=0.017, d=0.28), but there was no effect of acute sham DBS. Increases in corticomotor excitability observed with acute DBS were associated with higher microstructural integrity of ipsilesional corticospinal tract (r>0.70, p<0.017) and dentato-thalamo-cortical pathways (ρ>0.69, p<0.022). Gains in corticomotor excitability with acute DBS were associated with higher dexterity gains made with chronic DBS plus rehabilitation (r>0.65, p<0.028).
Conclusions: Acute DN-DBS leads to heightened ipsilesional corticomotor excitability in moderate-to-severe chronic stroke survivors. Effects of acute DN-DBS on physiology are contingent upon structural preservation of key white matter tracts and associated with motor gains made with chronic DN-DBS. Findings provide mechanistic support of DN-DBS as a potential therapy for post-stroke motor recovery and potential of TMS to monitor responses.
{"title":"Acute dentate nucleus deep brain stimulation modulates corticomotor excitability in chronic stroke survivors.","authors":"Xin Li, Kenneth B Baker, Kyle O'Laughlin, Yin-Liang Lin, Kelsey Baker, Robert Chen, Jacqueline Chen, Andre G Machado, Ela B Plow","doi":"10.1016/j.brs.2025.02.021","DOIUrl":"https://doi.org/10.1016/j.brs.2025.02.021","url":null,"abstract":"<p><strong>Background: </strong>Deep brain stimulation of the dentate nucleus (DN-DBS) is an emerging therapy to improve upper extremity (UE) motor function after stroke. This study sought to investigate the physiologic mechanisms of acute DN-DBS in chronic stroke survivors enrolled in a phase I trial for DN-DBS.</p><p><strong>Methods: </strong>Twelve chronic stroke participants with moderate-to-severe UE impairment received (acute) single sessions (≥45 min) of active DBS and sham DBS in a sham-controlled, double-blind, cross-over experiment (order randomized). Transcranial magnetic stimulation (TMS) was used to evaluate corticomotor physiology. We also characterized the relationship between acute DBS effects on physiology and baseline clinical and neuroimaging measures, and chronic DBS effects on motor function.</p><p><strong>Results: </strong>Acute active DBS led to an increase in ipsilesional corticomotor excitability evident as a 5.2% maximal stimulator output (MSO) reduction in active motor threshold (p=0.017, d=0.28), but there was no effect of acute sham DBS. Increases in corticomotor excitability observed with acute DBS were associated with higher microstructural integrity of ipsilesional corticospinal tract (r>0.70, p<0.017) and dentato-thalamo-cortical pathways (ρ>0.69, p<0.022). Gains in corticomotor excitability with acute DBS were associated with higher dexterity gains made with chronic DBS plus rehabilitation (r>0.65, p<0.028).</p><p><strong>Conclusions: </strong>Acute DN-DBS leads to heightened ipsilesional corticomotor excitability in moderate-to-severe chronic stroke survivors. Effects of acute DN-DBS on physiology are contingent upon structural preservation of key white matter tracts and associated with motor gains made with chronic DN-DBS. Findings provide mechanistic support of DN-DBS as a potential therapy for post-stroke motor recovery and potential of TMS to monitor responses.</p>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":" ","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.brs.2025.02.007
Konstantin Weise , Sergey N. Makaroff , Ole Numssen , Marom Bikson , Thomas R. Knösche
Introduction
Notwithstanding advances in computational models of neuromodulation, there are mismatches between simulated and experimental activation thresholds. Transcranial Magnetic Stimulation (TMS) of the primary motor cortex generates motor evoked potentials (MEPs). At the threshold of MEP generation, whole-head models predict macroscopic (at millimeter scale) electric fields (50–70 V/m) which are considerably below conventionally simulated cortical neuron thresholds (175–350 V/m).
Methods
We hypothesize that this apparent contradiction is in part a consequence of electrical field warping by brain microstructure. Classical neuronal models ignore the physical presence of neighboring neurons and microstructure and assume that the macroscopic field directly acts on the neurons. In previous work, we performed advanced numerical calculations considering realistic microscopic compartments (e.g., cells, blood vessels), resulting in locally inhomogeneous (micrometer scale) electric field and altered neuronal activation thresholds. Here we combine detailed neural threshold simulations under homogeneous field assumptions with microscopic field calculations, leveraging a novel statistical approach.
Results
We show that, provided brain-region specific microstructure metrics, a single statistically derived scaling factor between microscopic and macroscopic electric fields can be applied in predicting neuronal thresholds. For the cortical sample considered, the statistical method matches TMS experimental thresholds.
Conclusions
Our approach can be broadly applied to neuromodulation models, where fully coupled microstructure scale simulations may not be computationally tractable.
{"title":"Statistical method accounts for microscopic electric field distortions around neurons when simulating activation thresholds","authors":"Konstantin Weise , Sergey N. Makaroff , Ole Numssen , Marom Bikson , Thomas R. Knösche","doi":"10.1016/j.brs.2025.02.007","DOIUrl":"10.1016/j.brs.2025.02.007","url":null,"abstract":"<div><h3>Introduction</h3><div>Notwithstanding advances in computational models of neuromodulation, there are mismatches between simulated and experimental activation thresholds. Transcranial Magnetic Stimulation (TMS) of the primary motor cortex generates motor evoked potentials (MEPs). At the threshold of MEP generation, whole-head models predict macroscopic (at millimeter scale) electric fields (50–70 V/m) which are considerably below conventionally simulated cortical neuron thresholds (175–350 V/m).</div></div><div><h3>Methods</h3><div>We hypothesize that this apparent contradiction is in part a consequence of electrical field warping by brain microstructure. Classical neuronal models ignore the physical presence of neighboring neurons and microstructure and assume that the macroscopic field directly acts on the neurons. In previous work, we performed advanced numerical calculations considering realistic microscopic compartments (e.g., cells, blood vessels), resulting in locally inhomogeneous (micrometer scale) electric field and altered neuronal activation thresholds. Here we combine detailed neural threshold simulations under homogeneous field assumptions with microscopic field calculations, leveraging a novel statistical approach.</div></div><div><h3>Results</h3><div>We show that, provided brain-region specific microstructure metrics, a single statistically derived scaling factor between microscopic and macroscopic electric fields can be applied in predicting neuronal thresholds. For the cortical sample considered, the statistical method matches TMS experimental thresholds.</div></div><div><h3>Conclusions</h3><div>Our approach can be broadly applied to neuromodulation models, where fully coupled microstructure scale simulations may not be computationally tractable.</div></div>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":"18 2","pages":"Pages 280-286"},"PeriodicalIF":7.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143405730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-28DOI: 10.1016/j.brs.2025.02.020
Işıl Uluç, Mohammad Daneshzand, Mainak Jas, Parker Kotlarz, Kaisu Lankinen, Jennifer L Fiedler, Fahimeh Mamashli, Netri Pajankar, Tori Turpin, Lucia Navarro de Lara, Padmavathi Sundaram, Tommi Raij, Aapo Nummenmaa, Jyrki Ahveninen
Working memory (WM), short term maintenance of information for goal directed behavior, is essential to human cognition. Identifying the neural mechanisms supporting WM is a focal point of neuroscientific research. One prominent theory hypothesizes that WM content is carried in "activity-silent" brain states involving short-term synaptic changes. Information carried in such brain states could be decodable from content-specific changes in responses to unrelated "impulse stimuli". Here, we used single-pulse transcranial magnetic stimulation (spTMS) as the impulse stimulus and then decoded content maintained in WM from EEG using multivariate pattern analysis (MVPA) with robust non-parametric permutation testing. The decoding accuracy of WM content significantly enhanced after spTMS was delivered to the posterior superior temporal cortex during WM maintenance. Our results show that WM maintenance involves brain states, which are activity silent relative to other intrinsic processes visible in the EEG signal.
{"title":"Decoding auditory working memory content from EEG responses to auditory-cortical TMS.","authors":"Işıl Uluç, Mohammad Daneshzand, Mainak Jas, Parker Kotlarz, Kaisu Lankinen, Jennifer L Fiedler, Fahimeh Mamashli, Netri Pajankar, Tori Turpin, Lucia Navarro de Lara, Padmavathi Sundaram, Tommi Raij, Aapo Nummenmaa, Jyrki Ahveninen","doi":"10.1016/j.brs.2025.02.020","DOIUrl":"10.1016/j.brs.2025.02.020","url":null,"abstract":"<p><p>Working memory (WM), short term maintenance of information for goal directed behavior, is essential to human cognition. Identifying the neural mechanisms supporting WM is a focal point of neuroscientific research. One prominent theory hypothesizes that WM content is carried in \"activity-silent\" brain states involving short-term synaptic changes. Information carried in such brain states could be decodable from content-specific changes in responses to unrelated \"impulse stimuli\". Here, we used single-pulse transcranial magnetic stimulation (spTMS) as the impulse stimulus and then decoded content maintained in WM from EEG using multivariate pattern analysis (MVPA) with robust non-parametric permutation testing. The decoding accuracy of WM content significantly enhanced after spTMS was delivered to the posterior superior temporal cortex during WM maintenance. Our results show that WM maintenance involves brain states, which are activity silent relative to other intrinsic processes visible in the EEG signal.</p>","PeriodicalId":9206,"journal":{"name":"Brain Stimulation","volume":" ","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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