Transcranial electrical stimulation devices
Dennis Q. Truong, Niranjan Khadka, Angel V. Peterchev, and Marom Bikson
Oxford University Press | (2021) | The Oxford Handbook of Transcranial Stimulation, Second Edition 2 2-55 | 10.1093/oxfordhb/9780198832256.013.2
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Abstract:
Transcranial electrical stimulation (tES) devices apply electrical waveforms through electrodes placed on the scalp to modulate brain function. This chapter describes the principles, types, and components of tES devices as well as practical considerations for their use. All tES devices include a waveform generator, electrodes, and an adhesive or headgear to position the electrodes. tES dose is defined by the size and position of electrodes, and the waveform, duration, and intensity of the current. Many sub-classes of tES are named based on dose. This chapter focuses on low intensity tES, which includes transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS). tES electrode types are reviewed, including electrolyte-soaked sponge, adhesive hydrogel, high-definition, hand-held solid metal, free paste on electrode, and dry. Computational models support device design and individual targeting. The tolerability of tES is protocol specific, and medical grade devices minimize risk.
New paper in Frontiers in Cell and Developmental Biology
Direct Current Stimulation Disrupts Endothelial Glycocalyx and Tight Junctions of the Blood-Brain Barrier in vitro
Yifan Xia, Yunfei Li, Wasem Khalid, Marom Bikson & Bingmei M. Fu
Frontiers in Cell and Developmental Biology | (2021) 9 | https://doi.org/10.3389/fcell.2021.731028
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Abstract: Transcranial direct current stimulation (tDCS) is a non-invasive physical therapy to treat many psychiatric disorders and to enhance memory and cognition in healthy individuals. Our recent studies showed that tDCS with the proper dosage and duration can transiently enhance the permeability (P) of the blood-brain barrier (BBB) in rat brain to various sized solutes. Based on the in vivo permeability data, a transport model for the paracellular pathway of the BBB also predicted that tDCS can transiently disrupt the endothelial glycocalyx (EG) and the tight junction between endothelial cells. To confirm these predictions and to investigate the structural mechanisms by which tDCS modulates P of the BBB, we directly quantified the EG and tight junctions of in vitro BBB models after DCS treatment. Human cerebral microvascular endothelial cells (hCMECs) and mouse brain microvascular endothelial cells (bEnd3) were cultured on the Transwell filter with 3 μm pores to generate in vitro BBBs. After confluence, 0.1–1 mA/cm2 DCS was applied for 5 and 10 min. TEER and P to dextran-70k of the in vitro BBB were measured, HS (heparan sulfate) and hyaluronic acid (HA) of EG was immuno-stained and quantified, as well as the tight junction ZO-1. We found disrupted EG and ZO-1 when P to dextran-70k was increased and TEER was decreased by the DCS. To further investigate the cellular signaling mechanism of DCS on the BBB permeability, we pretreated the in vitro BBB with a nitric oxide synthase (NOS) inhibitor, L-NMMA. L-NMMA diminished the effect of DCS on the BBB permeability by protecting the EG and reinforcing tight junctions. These in vitro results conform to the in vivo observations and confirm the model prediction that DCS can disrupt the EG and tight junction of the BBB. Nevertheless, the in vivo effects of DCS are transient which backup its safety in the clinical application. In conclusion, our current study directly elucidates the structural and signaling mechanisms by which DCS modulates the BBB permeability.
New Publication in Brain Stimulation
High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
Erica Kreisberg, Zeinab Esmaeilpoura, Devin Adair, Niranjan Khadka, Abhishek Datta, Bashar W. Badran, Douglas Bremner, Marom Bikson
Brain Stimulation | (2021) 14 1419- 1430 | https://doi.org/10.1016/j.brs.2021.09.001
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Abstract:
Background
Transcutaneous auricular Vagus Nerve Stimulation (taVNS) applies low-intensity electrical current to the ear with the intention of activating the auricular branch of the Vagus nerve. The sensitivity and selectivity of stimulation applied to the ear depends on current flow pattern produced by a given electrode montage (size and placement).
Objective
We compare different electrodes designs for taVNS considering both the predicted peak electric fields (sensitivity) and their spatial distribution (selectivity).
Methods
Based on optimized high-resolution (0.47 mm) T1 and T2 weighted MRI, we developed an anatomical model of the left ear and the surrounding head tissues including brain, CSF/meninges, skull, muscle, blood vessels, fat, cartilage, and skin. The ear was further segmented into 6 regions of interest (ROI) based on various nerve densities: cavum concha, cymba concha, crus of helix, tragus, antitragus, and earlobe. A range of taVNS electrode montages were reproduced spanning varied electrodes sizes and placements over the tragus, cymba concha, earlobe, cavum concha, and crus of helix. Electric field across the ear (from superficial skin to cartilage) for each montage at 1 mA or 2 mA taVNS, assuming an activation threshold of 6.15 V/m, 12.3 V/m or 24.6 V/m was predicted using a Finite element method (FEM). Finally, considering every ROI, we calculated the sensitivity and selectivity of each montage.
Results
Current flow patterns through the ear were highly specific to the electrode montage. Electric field was maximal at the ear regions directly under the electrodes, and for a given total current, increases with decreasing electrode size. Depending on the applied current and nerves threshold, activation may also occur in the regions between multiple anterior surface electrodes. Each considered montage was selective for one or two regions of interest. For example, electrodes across the tragus restricted significant electric field to the tragus. Stimulation across the earlobe restricted significant electric field to the earlobe and the antitragus. Because of this relative selectivity, use of control ear montages in experimental studies, support testing of targeting. Relative targeting was robust across assumptions of activation threshold and tissue properties.
Discussion
Computational models provide additional insight on how details in electrode shape and placement impact sensitivity (how much current is needed) and selectivity (spatial distribution), thereby supporting analysis of existing approaches and optimization of new devices. Our result suggest taVNS current patterns and relative target are robust across individuals, though (variance in) axon morphology was not represented.
Segmented anatomy of outer ear, the region of interests (ROIs) of ABVN, and simulated taVNS montages. A1-A5, B1-B3 represent segmentation of outer ear skin, outer ear cartilage, fat, muscle, blood vessels, CSF, brain/grey-matter, as well as color coded ROIs (B4). C1-C10 indicate montages simulated.
Dr. Marom Bikson will participate in the 2021 Neuroergonomics Conference online.
Dr. Bikson will speak on “Can Neuromodulation Make Us Better: Changing Brain Activity with Wearable Brain Stimulation Devices” on Sept 15th. Download slides PDF
Dr. Bikson will co-direct a workshop Introduction to practical methods in low-intensity transcranial Electrical Stimulation, Sep 12th. Slides from the tES Workshop PDF
New publication in Neuroimage: Reports
Investigating the brain regions involved in tDCS-Enhanced category learning using finite element modeling
Aaron P. Jones, Monica Goncalves-Garcia, Benjamin Gibson, Michael C.S. Trumbo, Brian A. Coffman, Bradley Robert, Hope A. Gill, Teagan Mullins, Michael A. Hunter, Charles S.H. Robinson, Angela Combs, Niranjan Khadka, Marom Bikson, Vincent P. Clark
Neuroimage Reports | (2021) 4(1):100048 | https://doi.org/10.1016/j.ynirp.2021.100048
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Abstract: Transcranial direct current stimulation (tDCS) influences performance in many cognitive domains. However, the question of which brain networks are involved in these effects is rarely examined. In prior experiments we identified tDCS protocols that produce a large improvement in category learning. Here we examined which brain regions were involved by modelling and comparing the behavioral effects of different electrode placements. In Experiment 1, we placed electrodes at two cephalic sites found the be most effective in our prior studies (F10 and T5/P7), expecting an increased combined effect. However, no effect was found, suggesting that stimulation of additional far field regions using extracephalic electrodes in our prior studies may have been necessary for producing these effects. In Experiment 2, we used finite element modeling (FEM) to compare the E-fields produced by these montages. One region with large differences and that is accessible to tDCS was the cerebellum. We then tested the involvement of the cerebellum by placing electrodes below the inion vs. the left arm in thirty-six participants who received anodal, cathodal, or sham stimulation during training. Neither anodal nor cathodal cerebellar tDCS led to significant changes when compared with sham. These results suggest that neither far-field stimulation of the cerebellum nor nearby cranial nerves played a large causal role in our previous tDCS studies. To our knowledge, this one of the first studies to systematically compare the behavioral and energetic effects produced by different montages to identify the specific brain regions involved in the behavioral responses to tDCS.
FEM of electrode placements used in previous studies (left 3 columns), and experiment 1 of the current study (rightmost columns). The first row shows an inferior view for each montage. The second row shows a left lateral view. The third row shows a right lateral view. Note that behavioral effects of tDCS were observed in the first three montages, but not in the fourth.
New publication in Brain Stimulation
Adaptive current-flow models of ECT: Explaining individual static impedance, dynamic impedance, and brain current density
Gozde Unal , Jaiti K. Swami, Carliza Canela, Samantha L. Cohen, Niranjan Khadka, Mohamad FallahRad, Baron Short, Miklos Argyelan, Harold A. Sackeim & Marom Bikson
Brain Stimulation | (2021) 14(5):1154-1168 | https://doi.org/10.1016/j.brs.2021.07.012
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Abstract: Background: Improvements in electroconvulsive therapy (ECT) outcomes have followed refinement in device electrical output and electrode montage. The physical properties of the ECT stimulus, together with those of the patient's head, determine the impedances measured by the device and govern current delivery to the brain and ECT outcomes. Objective: However, the precise relations among physical properties of the stimulus, patient head anatomy, and patient-specific impedance to the passage of current are long-standing questions in ECT research and practice. To this end, we develop a computational framework based on diverse clinical data sets. Methods: We developed anatomical MRI-derived models of transcranial electrical stimulation (tES) that included changes in tissue conductivity due to local electrical current flow. These “adaptive” models simulate ECT both during therapeutic stimulation using high current (~1 A) and when dynamic impedance is measured, as well as prior to stimulation when low current (~1 mA) is used to measure static impedance. We modeled two scalp layers: a superficial scalp layer with adaptive conductivity that increases with electric field up to a subject-specific maximum (sSS), and a deep scalp layer with a subject-specific fixed conductivity (sDS). Results: We demonstrated that variation in these scalp parameters may explain clinical data on subjectspecific static impedance and dynamic impedance, their imperfect correlation across subjects, their relationships to seizure threshold, and the role of head anatomy. Adaptive tES models demonstrated that current flow changes local tissue conductivity which in turn shapes current delivery to the brain in a manner not accounted for in fixed tissue conductivity models. Conclusions: Our predictions that variation in individual skin properties, rather than other aspects of anatomy, largely govern the relationship between static impedance, dynamic impedance, and ECT current delivery to the brain, themselves depend on assumptions about tissue properties. Broadly, our novel modeling pipeline opens the door to explore how adaptive-scalp conductivity may impact transcutaneous electrical stimulation (tES).
July 22, 2021 . (8-9 AM ET)n Prof. Marom Bikson speaks (online) to Justus-Liebig-University Gieße on “Technology and fundamentals of tACS”
Slides: PDF
New publication in Nature Scientific Reports
Acute effect of high‑definition and conventional tDCS on exercise performance and psychophysiological responses in endurance athletes: a randomized controlled trial
Daniel Gomes da Silva Machado, Marom Bikson, Abhishek Datta, Egas Caparelli‑Dáquer, Gozde Unal, Abrahão F. Baptista, Edilson Serpeloni Cyrino, Li Min Li , Edgard Morya, Alexandre Moreira & Alexandre Hideki Okano
Scientific Reports | (2021) 11:13911 | https://doi.org/10.1038/s41598-021-92670-6
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Abstract: Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called “conventional” tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg−1 min−1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.
Below please find information in regards to Psychology (Behavioral and Cognitive Neuroscience) PhD student lvan Iotzov’s second exam (defense of research proposal), which is open to all and will take place on Tuesday, May 25th at 11:00am via Zoom (email iiotzov@gradcenter.cuny.edu for Zoom ID). Ivan's abstract is also below.
Neural Speech Tracking: Mechanisms and Practical Applications
Speech signals have a strong and consistent effect on brain activity. Many previous studies have demonstrated the ability to find correlations between the amplitude envelope of ongoing speech and evoked responses measured through EEG or MEG. This correlation appears to be modulated by attention, as well as other high-level factors. It is of particular interest because of the possible practical applications of speech tracking in the steering of hearing aid devices and other assistive hearing devices. These devices are typically difficult to tune and the ability to use an objective neural signal as the basis for their tuning would be a great advancement in comfort and efficacy for their users. In this proposal, investigate the correlation between speech intelligibility and the neural tracking of a speech segment. We show a link between the neural tracking of speech and performance on a behavioral word-recognition task. We also develop a novel behavioral paradigm for the investigation of these effects and show preliminary data demonstrating the validity of this new paradigm. Additionally, we propose further experiments to illuminate the mechanisms behind this speech tracking phenomenon using novel manipulations of speech stimuli. Together, these aims and methods provide a basis for the use of speech tracking as an objective neural measure of intelligibility of speech and look to shed light on the oscillatory mechanisms that create the speech tracking phenomenon.
New publication in Frontiers in Neuroergonomics
Transcranial Direct Current Stimulation (tDCS) Augments the Effects of Gamified, Mobile Attention Bias Modification
Sarah Myruski, Hyein Cho, Marom Bikson, & Tracy A. Dennis-Tiwary
Frontiers in Neuroergonomics | (2021) | https://doi.org/10.3389/fnrgo.2021.652162
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Abstract: Anxiety-related attention bias (AB) is the preferential processing of threat observed in clinical and sub-clinical anxiety. Attention bias modification training (ABMT) is a computerized cognitive training technique designed to systematically direct attention away from threat and ameliorate AB, but mixed and null findings have highlighted gaps in our understanding of mechanisms underlying ABMT and how to design the most effective delivery systems. One neuromodulation technique, transcranial direct current stimulation (tDCS) across the pre-frontal cortex (PFC) may augment the effects of ABMT by strengthening top-down cognitive control processes, but the evidence base is limited and has not been generalized to current approaches in digital therapeutics, such as mobile applications. The present study was a single-blind randomized sham-controlled design. We tested whether tDCS across the PFC, vs. sham stimulation, effectively augments the beneficial effects of a gamified ABMT mobile app. Thirty-eight adults (Mage = 23.92, SD = 4.75; 18 females) evidencing low-to-moderate anxiety symptoms were randomly assigned to active or sham tDCS for 30-min while receiving ABMT via a mobile app. Participants reported on potential moderators of ABMT, including life stress and trait anxiety. ECG was recorded during a subsequent stressor to generate respiratory sinus arrhythmia (RSA) suppression as a metric of stress resilience. ABMT delivered via the app combined with tDCS (compared to sham) reduced AB and boosted stress resilience measured via RSA suppression, particularly for those reporting low life stress. Our results integrating tDCS with ABMT provide insight into the mechanisms of AB modulation and support ongoing evaluations of enhanced ABMT reliability and effectiveness via tDCS.
Dr. Mahima Sharma, Postdoctoral Fellow in Professor Parra's lab in the CCNY BME Department, is the speaker of the next BME seminar on Wednesday, May 12 at 3pm
Presentation: Synaptic evidence for the cumulative effects of weak DCS in spaced learning in rat hippocampus
Electric fields generated during direct current stimulation (DCS) are known to modulate activity dependent synaptic plasticity in-vitro. This provides a mechanistic explanation for the lasting behavioral effects observed with transcranial direct current stimulation (tDCS) in human learning experiments. However, previous in-vitro synaptic plasticity experiments show relatively small effects despite using strong fields compared to what is expected with conventional tDCS in humans (20 V/m vs. 1 V/m). We propose that effects of DCS on synaptic long-term potentiation (LTP) accumulate over time in a spaced learning paradigm, thus revealing effects at more realistic field intensities. As predicted, DCS applied during repeated bouts of theta burst stimulation (TBS) resulted in an increase of LTP. This spaced learning effect saturated quickly with strong TBS protocols and stronger fields. In contrast, weaker TBS and the weakest electric fields of 2.5 V/m resulted in the strongest relative efficacies (12% boost in LTP per 1 V/m applied). These results support the notion that the effects of weak fields during DCS accumulate through an increasing synaptic strength after repeated bouts of learning and bridge the gap in terms of efficacy between in-vitro DCS and human tDCS experiments.
Gozde Unal, a PhD student in the lab of Dr. Marom Bikson will present her defense of her research proposal on Tuesday, May 11, 2021 at 9am. A copy of her abstract is below. If you would like to attend, please contact Gozde at gunal000@citymail.cuny.edu for the Zoom meeting ID.
ADAPTIVE CURRENT-FLOW MODELS OF ECT:
EXPLAINING INDIVIDUAL STATIC IMPEDANCE, DYNAMIC IMPEDANCE, AND BRAIN CURRENT DENSITY
Abstract
Improvements in electroconvulsive therapy (ECT) outcomes have followed refinement in device electrical output and electrode montage. The physical properties of the ECT stimulus, together with those of the patient’s head, determine the impedances measured by the device and govern current delivery to the brain and ECT outcomes. However, the precise relations among physical properties of the stimulus, patient head anatomy, and patient-specific impedance to the passage of current are long-standing questions in ECT research and practice.
We developed anatomical MRI-derived models of transcranial electrical stimulation (tES) that included changes in tissue conductivity due to local electrical current flow. These “adaptive” models simulate ECT both during therapeutic stimulation using high (~1 A) current and when dynamic impedance is measured, as well as prior to stimulation when low (~1 mA) current is used to measure static impedance. We modeled two scalp layers: a superficial scalp layer with adaptive conductivity that increases with electric field up to a subject specific maximum,
(σSS),
and a deep scalp layer with a subject-specific fixed conductivity,
(σDS).
We demonstrate that variation in these scalp parameters explain clinical data on subject-specific static impedance and dynamic impedance, their imperfect correlation across subjects, their relationships to seizure threshold, and the role of head anatomy. Adaptive tES models demonstrate that current flow changes local tissue conductivity which in turn shapes current delivery to the brain in a manner not accounted for in fixed tissue conductivity models.
Our predictions that variation in individual skin properties, rather than other aspects of anatomy, largely govern the relationship between static impedance, dynamic impedance, and current delivery to the brain, are themselves subject to assumptions about tissue properties. Broadly, our novel pipeline for tES models is important in ongoing efforts to optimize devices, personalize interventions, and explain clinical findings.
Maximilian Nentwich, a PhD student in the lab of Dr. Lucas Parra will present his defense of her research proposal on Monday, May 2, 2021 at 1pm. A copy of his abstract is below. If you would like to attend, please contact Maximilian at mnentwi000@citymail.cuny.edu for the Zoom meeting ID.
NEURAL RESPONSES TO NATURALISTIC STIMULI
Maximilian Nentwich
Department of Biomedical Engineering
Mentor: Lucas C. Parra
Abstract
While experiments in neuroscience traditionally focus on well-defined static stimuli, the
results of these studies often fail to explain neural processes in naturalistic settings. Naturalistic
stimuli, like movies, allow for free eye movements and contain various complex visual, semantic
and narrative features. However, defining these features requires subjective and labor-intensive
manual annotations. Alternatively, the reliability of neural signals between brain areas or
subjects can be analyzed. This has led to the identification of brain areas that are correlated
between subjects, dependent on the narrative content of movies and the subjects attention.
Similarly, patterns of correlations between brain areas, termed ‘functional connectivity’ (FC), are
reliably activated during resting state and movie tasks.
FC has been studied extensively with fMRI, is reliable across methods and laboratories
and related to various psychiatric and demographic phenotypes. However, FC has not been
studied well in EEG. Therefore, aim 1 is to compare FC between fMRI and EEG. We
hypothesize that patterns of FC measured by fMRI and EEG are similar, and that FC in
both modalities is related to phenotypic variables. To test this, we analyzed a database of
EEG and fMRI recorded from over 1600 children and adolescents during resting state and
movie tasks. We computed FC matrices in fMRI with Pearson’s correlation, and in EEG with the
imaginary part of coherence (iCOH), a measure of phase-coupling. We then compared the
spatial patterns of FC by correlating connectivity matrices of EEG and fMRI. FC matrices of both
measures were related to phenotypes by multivariate distance matrix regression (MDMR), which
determines if differences of connectivity matrices correspond to differences in phenotypic
measures. Contrary to our hypothesis, we found that the spatial patterns of FC in EEG and fMRI
are distinct. However, FC in both modalities is related to phenotypes. We conclude that EEG
and fMRI FC reflect different neural processes.
To investigate which features of movies drive neural responses most reliably we
analyzed an additional dataset of intracranial EEG using the same movies as the FC dataset.
Movies contain several visual features, particularly temporal contrast, scene cuts, and elicit
saccades. Previous studies on fMRI and EEG suggest that motion, particularly of socially
relevant stimuli, elicits the strongest neural responses in movies. In aim 2 we test whether
motion in movies leads to neural responses in iEEG. We hypothesise that motion elicits
stronger responses than other visual features. Further, we predict that motion of
semantic objects, elicits stronger responses than other motion. We analysed the data with
a linear systems identification approach to identify the neural responses to stimuli extracted
from the movies. We could not find any significant response to optical flow, a measure of
motion. However, we found strong responses after scene cuts and saccades. Additionally,
scene cuts identified as semantic lead to different responses than scene cuts without semantic
content. We conclude that opposed to visual motion, salient novelty events drive neural
responses to movies. We further propose a recognition memory task to test whether semantic
scene cuts are better encoded in memory.
5th International Network of tES-fMRI (INTF) Webinar on Individually Optimized Non-Invasive Brain Stimulation
May 27th, 2021 for a two-hour webinar on individually optimized non-invasive brain stimulation co-hosted by Marom Bikson and Hamed Ekhtiari.
Registation and full details here
(Dr. Bikson’s presentation slides on “Closed looped stimulation: Why bother?” PDF)
In this online INTF Webinar exploring the Fundamentals & Challenges of Individually Optimized Non-Invasive Brain Stimulation, we are joined by Dr Marom Bikson (City University of New York), Dr Til Ole Bergman (University of Mainz), Dr Ines Violante (University of Surrey), Dr Romy Lorenz (University of Cambridge), Dr Alik Widge (University of Minnesota), Dr Flavio Frohlich (University of North Carolina), and Dr Hamed Ekhtiari (Laureate Institute for Brain Research) for two hours of lectures, discussions, and practical challenges, including:
• Closed-loop stimulation
• Brain-state dependent brain stimulation
• A framework for optimizing tES with closed-loop real-time fMRI
• Searching through the large brain stimulation parameter space
• What NIBS can learn from closed-loop invasive brain stimulation
• Closed-loop transcranial alternating current stimulation: Towards personalized treatments
• Online closed-loop real-time tES-fMRI: Potentials and challenges
The knowledge gained in this webinar will provide all attendees with the required knowledge to design, set up, and carry out their own optimized NIBS study, and is suitable for both new users of non-invasive brain stimulation techniques, and those with an existing knowledge of how to use these techniques
Dr. Marom Bikson speaks at Advances in Transcranial Direct Current Stimulation in Psychiatric Disorders on April 17, 2021 on “Best Practices and Latest Developments in tDCS”
Slides PDF
Zeinab Esmaeilpour, a PhD student in the lab of Dr. Marom Bikson will present her defense of her research proposal on Friday, April 2, 2021 at 3pm. A copy of her abstract is below. If you would like to attend, please contact Zeinab at zesmaei000@citymail.cuny.edu for the Zoom meeting ID.
Abstract
Understanding the cellular mechanism of direct current (DC) and kilohertz (kHz) electrical stimulation is of broad interest in neuromodulation in both invasive and noninvasive methods. More specifically there is large mismatch between enthusiasm to for clinical applications of the methods and understanding of DC and kHz mechanism of action. In the case of kilohertz stimulation, there is a well-established and validated low pass filtering characteristics of neuronal membrane. This feature attenuates sensitivity of nervous system to any waveforms with high frequency components. On the contrary, kilohertz stimulation has revolutionized spinal cord stimulation and even generated promising results in transcranial stimulation.
Effects DC stimulation have been studied in neuronal depolarization/hyperpolarization, synaptic plasticity and neuronal network modulation. Recent evidence suggests that DC stimulation can induce polarity dependent water exchange across blood brain barrier (BBB) in cell culture experiments through a mechanism called electroosmosis. Modulating water exchange rate across BBB is of broad interest in neurological disease such as dementia, Alzheimer’s, and stroke where brain clearance system is disrupted. Investigating effect of electrical stimulation on water exchange across BBB can potentially lead to therapeutic pathways.
This dissertation provides the first direct in vitro evidence on acute effects kilohertz electrical stimulation in central nervous system using both unmodulated and Amplitude-modulated waveforms. While supported by membrane characteristic of neurons, we uncovered that using low kilohertz stimulation diminishes the sensitivity of hippocampal neurons to electrical stimulation. Moreover, using Amplitude-Modulated waveform can generate a different pattern of modulation and even higher sensitivity to stimulation. However, required electric field in this case is significantly higher than low frequency stimulation methods such as tACS. We plan to study effect of direct current stimulation on water exchange rate across blood brain barrier (BBB) as new avenue of mechanism for electrical stimulation. We will investigate whether tDCS can increase water exchange rate and blood flow in healthy population using and advanced MR imaging technique.
Below please find information in regards to BME PhD student Jason Ki’s dissertation defense, which is open to all and will take place on Tuesday, March 30th at 3:00pm via Zoom. Please email Jason at jki00@citymail.cuny.edu for the Zoom link. Jason’s abstract is also below.
When the Brain Plays a Game:
Neural responses to visual dynamics during naturalistic visual tasks.
Department of Biomedical Engineering
Jason Ki
Mentor: Lucas C Parra
ABSTRACT
Many day-to-day tasks involve processing of complex visual information in a continuous stream. While much of our knowledge on visual processing has been established from reductionist approaches in lab-controlled settings, very little is known about the processing of complex dynamic stimuli experienced in everyday scenarios. Traditional investigations employ event-related paradigms that involve presentation of simple stimuli at select locations in visual space or discrete moments in time. In contrast, visual stimuli in real-life are highly dynamic, spatially-heterogeneous, and semantically rich. Moreover, traditional experiments impose unnatural task constraints (e.g. inhibited saccades), thus, it is unclear whether theories developed under the reductionist approach apply in naturalistic settings. Given these limitations, alternative experimental paradigms and analysis methods are necessary. Here, we introduce a new approach for investigating visual processing, applying the system identification (SI) framework. We investigate the modulation of stimulus-evoked responses during a naturalistic task (i.e. kart race game) using non-invasive scalp recordings.
In recent years, multivariate modeling approaches have become increasingly popular for assessing neural response to naturalistic stimulus. Encoding models use stimulus patterns to predict brain responses and decoding models use patterns of brain responses to predict stimulus that drove these responses. In this dissertation, we employ a hybrid method that “encodes” the stimulus to predict “decoded” brain responses. With this approach, we measure the stimulus-response correlation (SRC, i.e. temporal correlation of neural response and dynamic stimulus) to assess the strength of stimulus-evoked activity to uniquely experienced naturalistic stimulus. To demonstrate this, we measured the SRC during a kart race videogame. We find that SRC increased with active play of the game, suggesting that stimulus-evoked activity is modulated by the visual task demands. Furthermore, we analyzed the selectivity of neural response across the visual space. While it is well-established that neural response is spatially selective to discrete stimulus, it is unclear whether this is true during naturalistic stimulus presentation. To assess this, we measured the correlation of neural response with optical flow magnitude at individual locations on the screen during the videogame. We find that the SRC is greater for locations in space that are task-relevant, enhancing during active play. Moreover, the spatial selectivity differs across scalp locations, which suggest that individual brain regions are spatially selective to different visual dynamics.
Overall, we leveraged the SI framework to investigate visual processing during a naturalistic stimulus presentation, extending visual research to ecologically valid paradigms. Our findings shed new insights about the stimulus-evoked neural response to visual dynamics during a uniquely experienced naturalistic visual task. We show that selectivity of neural response can be spatially-resolved at pixel-level from a low-SNR EEG. In the future, by further probing other spatial and temporal dimensions of the stimuli (beyond optical flow), we may gain new insights into how neural signals convey visual processing during dynamic natural visual experiences.
New publication in frontiers in Human Neuroscience
International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)
Adam D. Farmer, Adam Strzelczyk, Alessandra Finisguerra, Alexander V. Gourine, Alireza Gharabaghi, Alkomiet Hasan, Andreas M. Burger, Andrés M. Jaramillo, Ann Mertens, Arshad Majid, Bart Verkuil, Bashar W. Badran, Carlos Ventura-Bort, Charly Gaul, Christian Beste, Christopher M. Warren, Daniel S. Quintana, Dorothea Hämmerer, Elena Freri, Eleni Frangos, Eleonora Tobaldini, Eugenijus Kaniusas, Felix Rosenow, Fioravante Capone, Fivos Panetsos, Gareth L. Ackland, Gaurav Kaithwas, Georgia H. O'Leary, Hannah Genheimer, Heidi I. L. Jacobs, Ilse Van Diest, Jean Schoenen, Jessica Redgrave, Jiliang Fang, Jim Deuchars, Jozsef C. Széles, Julian F. Thayer, Kaushik More, Kristl Vonck, Laura Steenbergen, Lauro C. Vianna, Lisa M. McTeague, Mareike Ludwig, Maria G. Veldhuizen, Marijke De Couck, Marina Casazza, Marius Keute, Marom Bikson, Marta Andreatta, Martina D'Agostini, Mathias Weymar, Matthew Betts, Matthias Prigge, Michael Kaess, Michael Roden, Michelle Thai, Nathaniel M. Schuster, Nicola Montano, Niels Hansen, Nils B. Kroemer, Peijing Rong, Rico Fischer, Robert H. Howland, Roberta Sclocco, Roberta Sellaro, Ronald G. Garcia, Sebastian Bauer, Sofiya Gancheva, Stavros Stavrakis, Stefan Kampusch, Susan A. Deuchars, Sven Wehner, Sylvain Laborde, Taras Usichenko, Thomas Polak, Tino Zaehle, Uirassu Borges, Vanessa Teckentrup, Vera K. Jandackova, Vitaly Napadow, & Julian Koenig
Frontiers in Human Neuroscience | (2021) 14:568051 | https://doi.org10.3389/fnhum.2020.568051
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Abstract: Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice.
A subject in Marom Bikson’s research group using the taVNS device with telemedicine support.
While COVID’s often deadly outcome has resulted in the worst pandemic in a century, studies are unveiling a post-COVID phase for survivors during which neuropsychiatric symptoms, such as fatigue, anxiety and depression, can occur. How to treat this debilitating phase, called NeuroCOVID, is the challenge City College of New York biomedical engineer Marom Bikson and his team are tackling.
The first stage of COVID is characterized by fever, heart or lung problems. NeuroCOVID is second stage, characterized by one or a combination of symptoms like vertigo, loss of smell, headaches, fatigue and irritability, as well as anxiety and depression, said Bikson, professor in the Grove School of Engineering. These second stage symptoms can persist, leaving patients with ongoing mental health complications.
Bikson is leading a multi-center trial utilizing a revolutionary noninvasive technology developed in his neural engineering lab. It involves stimulating the vagus nerve in an attempt to both directly activate brain healing mechanisms and also reduce inflammation in participants with reported neuroCOVID symptoms. Using this two-prong approach, which aims to reverse neuropathic changes in brain function while also reducing inflammation (which is known to cause a host of problems in the body) it is hoped that some or all of the patients’ neuroCOVID symptoms will subside.
In addition to state-of-the-art technology to activate the nervous system, the clinical trial incorporates advanced home-based real-time monitoring of patient vitals, and a clinician-patient portal for real-time assessment of progress and remote-control of the technology. “This is truly personalized medicine, with the ability for physicians to adjust therapy in real-time and monitor patient progress at-home with rigor usually reserved for advanced medical centers. The trial is one example of hundreds of medical treatments developed at CCNY being tested or in use,” said Bikson.
The device used in the trial includes a small clip placed on the ear. A hand-held stimulator provides barely perceptible electrical stimulation to the ear to stimulate the auricula branch of the vagus nerve. The technique is generally called transcutaneous Auricular Nerve Stimulation or tAVNS. The Bikson group worked with clinicians at the Medical University of South Carolina (MUSC) to optimize tAVNS so it can be used reliably and easily in patients’ homes. The partners also designed a trial allowing entirely home-based treatment for NeuroCOVID.
Bikson directs one of the most productive medical device design labs in the country with support from the National Institutes of Health and numerous corporate partners. It develops medical devices to treat neurological and psychiatric disorders, including devices that apply minute levels of energy to activate the brain and nervous system.
The devices for the NeuroCOVID trial are built by Soterix Medical, a medical device company co-founded by Bikson as a spin-off from CCNY research.
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