Mechanisms and Effects of Transcranial Direct Current Stimulation

Dose-Response: An International Journal January-March 2017:1-22 DOI: 10.1177/1559325816685467

James Giordano, Marom Bikson, Emily S. Kappenman, Vincent P. Clark, H. Branch Coslett, Michael R. Hamblin, Roy Hamilton, Ryan Jankord, Walter J. Kozumbo, R. Andrew McKinley, Michael A. Nitsche, J. Patrick Reilly, Jessica Richardson, Rachel Wurzman, and Edward Calabrese

Abstract: The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical popu- lations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising appli- cations include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged.

Download: Final OnLine Proceedings – Dose Response Journal

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Computational models of Bitemporal, Bifrontal and Right Unilateral ECT predict differential stimulation of brain regions associated with efficacy and cognitive side effects.

Bai S, Gálvez V, Dokos S, Martin D, Bikson M, Loo C.
Eur Psychiatry. 2016 Dec 29;41:21-29. doi: 10.1016/j.eurpsy.2016.09.005. [Epub ahead of print]
PMID: 28049077

Full paper: 10.1016@j.eurpsy.2016.09.005

Abstract: 

BACKGROUND: Extensive clinical research has shown that the efficacy and cognitive outcomes of electroconvulsive therapy (ECT) are determined, in part, by the type of electrode placement used. Bitemporal ECT (BT, stimulating electrodes placed bilaterally in the frontotemporal region) is the form of ECT with relatively potent clinical and cognitive side effects. However, the reasons for this are poorly understood.
OBJECTIVE: This study used computational modelling to examine regional differences in brain excitation between BT, Bifrontal (BF) and Right Unilateral (RUL) ECT, currently the most clinically-used ECT placements. Specifically, by comparing similarities and differences in current distribution patterns between BT ECT and the other two placements, the study aimed to create an explanatory model of critical brain sites that mediate antidepressant efficacy and sites associated with cognitive, particularly memory, adverse effects.
METHODS: High resolution finite element human head models were generated from MRI scans of three subjects. The models were used to compare differences in activation between the three ECT placements, using subtraction maps.
RESULTS AND CONCLUSION: In this exploratory study on three realistic head models, Bitemporal ECT resulted in greater direct stimulation of deep midline structures and also left temporal and inferior frontal regions. Interpreted in light of existing knowledge on depressive pathophysiology and cognitive neuroanatomy, it is suggested that the former sites are related to efficacy and the latter to cognitive deficits. We hereby propose an approach using binarised subtraction models that can be used to optimise, and even individualise, ECT therapies

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Thursday, February 09, 2017, 03:30PM, The City College of New York (CCNY) NAC 4/156

Prof. Luca Parra (CCNY Biomedical Engineering), On Brainwaves and Videos and Video Games 

What are the immediate neural response of the brain to natural stimuli, in particular audiovisual narratives and video games? To answer this question we record EEG while subjects are exposed to the identical audiovisual narratives and measure inter-subject correlation, which captures how similarly and reliably different people respond to the same natural stimulus. We find that inter-subject correlation of EEG is strongly modulated by attention, correlates with long term memory, and provides a quantitative estimate for “audience engagement”. In children and adolescents watching videos we find changes with age and gender that are consistent with an increase in diversity of brain responses as they mature. During video game play, which are unique experiences that preclude correlation across subjects, we measure the strength of stimulus-response correlations instead. We found that correlation with both auditory and visual responses drive the correlation observed between subjects for video and that they are are modulated by attention in video game play. Importantly, the strongest response to visual and auditory features had nearly identical neural origin suggesting that the dominant response of the brain to natural stimuli is supramodal.

Feb 1, 2017 9:00 AM-12:00 PM: CE Workshop 2. Best-Practices of Transcranial Direct Current
Stimulation (tDCS) for Effective and Reliable Outcomes
Presenter: Marom Bikson
Location: Salon D (Mardi Gras Ballroom)

Download slides: INS_tDCS_2017_Bikson_Final.compressed

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Feb 2, 2017. 9:00 AM-10:30 AM. Invited Symposium 1. Electrical Brain Stimulation and Cognitive Disorders
Chair: Marom Bikson
Presenters: Marom Bikson, Adam J. Woods, Leigh Charvet
Location: Carondelet (Grand Ballroom)

Download slides: INS_2017final2

 

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Human cochlear hydrodynamics: A high-resolution μCT-based finite element study

Annalisa De Paolis, Hirobumi Watanabe, Jeremy T. Nelson, Marom Bikson, Mark Packer, Luis Cardoso

Journal of Biomechanics 50 (2017) 209–216

PDF: Human cochlear hydrodynamics   Journal Link

Abstract: Measurements of perilymph hydrodynamics in the human cochlea are scarce, being mostly limited to the fluid pressure at the basal or apical turn of the scalae vestibuli and tympani. Indeed, measurements of fluid pressure or volumetric flow rate have only been reported in animal models. In this study we imaged the human ear at 6.7 and 3-mm resolution using mCT scanning to produce highly accurate 3D models of the entire ear and particularly the cochlea scalae. We used a contrast agent to better distinguish soft from hard tissues, including the auditory canal, tympanic membrane, malleus, incus, stapes, ligaments, oval and round window, scalae vestibule and tympani. Using a Computational Fluid Dynamics (CFD) approach and this anatomically correct 3D model of the human cochlea, we examined the pressure and perilymph flow velocity as a function of location, time and frequency within the auditory range. Perimeter, surface, hydraulic diameter, Womersley and Reynolds numbers were computed every 45° of rotation around the central axis of the cochlear spiral. CFD results showed both spatial and temporal pressure gradients along the cochlea. Small Reynolds number and large Womersley values indicate that the perilymph fluid flow at auditory frequencies is laminar and its velocity profile is plug-like. The pressure was found 102–106° out of phase with the fluid flow velocity at the scalae vestibule and tympani, respectively. The average flow velocity was found in the sub-mm/s to nm/s range at 20–100 Hz, and below the nm/s range at 1–20 kHz.

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Published in the same issue of Brain Stimulation.

 

—- Direct Current Stimulation Alters Neuronal Input/Output Function.

Lafon B, Rahman A, Bikson M, Parra LC. Brain Stimul. 2016 Sep 1. pii: S1935-861X(16)30248-0. doi: 10.1016/j.brs.2016.08.014.

PDF: IO_tDCS_2017

 

— Direct Current Stimulation Modulates LTP and LTD: Activity Dependence and Dendritic Effects

Kronberg G, Bridi M, Abel T, Bikson M, Parra LC Brain Stimul. 2016 10 (2017) 51–58

PDF: Dendrites_tDCS_2017

 

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Conference information

NYC Neuromodulation 2017 will focus on technologies and mechanism for advanced brain stimulation in areas that include transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial magnetic stimulation (TMS), high-definition transcranial direct current stimulation (HD-tDCS), electroconvulsive therapy (ECT), deep brain stimulation (DBS), and other emerging areas. Applications span treatment of neuropsychiatric disorders, neurorehabilitation, and performance enhancement. Interactive lectures from key opinion leaders and emerging young scientists, poster sessions with abstracts published in Brain Stimulation and extensive opportunities to network with colleagues, along with an exhibit showcase featuring the latest neuromodulation technologies are all part of the main conference agenda.

This conference is among the most forward-looking neuromodulation meetings with the goal of advancing innovation from bench-top to bedside and home. Given the increased media, public, and commercial interest in personal non-invasive brain stimulation, the 2017 meeting will emphasize emerging “consumer” technologies, and their scientific and regulatory barriers. The off-label use of new clinical protocols will be addressed from scientific, medical, and regulatory perspectives. The conference will also focus on timely and novel targets of neuromodulation including glia, as well as new waveforms including high-rate (10 kHz) stimulation. Representatives from funding agencies and journal editors will be available to discuss priorities. NYC Neuromodulation is the largest meeting focused on non-invasive neuromodulation in North America, but this year it considers the role of invasive and non-invasive techniques in the continuum of care.

Chair: Marom Bikson

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Front. Hum. Neurosci., 12 January 2017 | https://doi.org/10.3389/fnhum.2016.00695

Cerebellar tDCS: A Novel Approach to Augment Language Treatment Post-stroke

People with post-stroke aphasia may have some degree of chronic deficit for which current rehabilitative treatments are variably effective. Accumulating evidence suggests that transcranial direct current stimulation (tDCS) may be useful for enhancing the effects of behavioral aphasia treatment. However, it remains unclear which brain regions should be stimulated to optimize effects on language recovery. Here, we report on the therapeutic potential of right cerebellar tDCS in augmenting language recovery in SMY, who sustained bilateral MCA infarct resulting in aphasia and anarthria. We investigated the effects of 15 sessions of anodal cerebellar tDCS coupled with spelling therapy using a randomized, double-blind, sham controlled within-subject crossover trial. We also investigated changes in functional connectivity using resting state functional magnetic resonance imaging before and 2 months post-treatment. Both anodal and sham treatments resulted in improved spelling to dictation for trained and untrained words immediately after and 2 months post-treatment. However, there was greater improvement with tDCS than with sham, especially for untrained words. Further, generalization to written picture naming was only noted during tDCS but not with sham. The resting state functional connectivity data indicate that improvement in spelling was accompanied by an increase in cerebro-cerebellar network connectivity. These results highlight the therapeutic potential of right cerebellar tDCS to augment spelling therapy in an individual with large bilateral chronic strokes.

 

Full paper: fnhum-10-00695   Journal link: Link

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