Prof. Bikson quoted on "Brain Hacking" in Chicago Tribune

Scientists, entrepreneurs in Chicago area tackle ‘brain hacking’

March 3, 2017, by Ted Gregory

Link to article

Selection: “Marom Bikson is optimistic and pragmatic. A biomedical engineering professor and co-director of Neural Engineering at the City College of New York, Bikson said it is clear that tDCS can change the brain. Many prospective users are unwilling to wait for lengthy human trials and related research before trying the technology.

“Among scientists who are incredulous or skeptical, the concern is often that we’re moving too fast,” Bikson said. But people who are suffering from depression, chronic pain and cognitive decline “have a different time scale,” he said. “They don’t have 10 years, and I don’t blame them for looking for alternatives.”

 

Shown equipment by Soterix Medical.

Neural Engineering
Brain-Hackers Vie to Enhance Human Performance

Wall Street Journal, Feb 24, 2017

By TOMIO GERON

Full article link

Abridged article:

Hacking software or network-connected devices is so 21st century. A new crop of forward-thinking entrepreneurs wants to hack the ultimate computer: the brain.

Enhancing or altering the brain with technology may sound like a concept for the cyborgs of science fiction, but Silicon Valley startups are already at it—with venture capitalists’ backing. A range of noninvasive wearable devices have hit the consumer market using electrical stimulation to sharpen physical and mental performance or to improve relaxation….

Interest in brain devices fits squarely within Silicon Valley’s ever-growing do-it-yourself biohacking and quantified-self movement, where people obsessively measure everything from their carbohydrate intake to mental acuity to sleep patterns. And the trend ties in with popular millennial pursuits like meditation, mindfulness and nontraditional remedies including nootropics.

In Silicon Valley, where tech executives are always seeking an edge, brain hackers have found a willing market for experimentation as a natural extension of that impulse.

Los Gatos, Calif.-based Thync has raised about $23 million from Noosphere Ventures, Khosla Ventures and Andreessen Horowitz, according to PitchBook. The company says its $199 device can improve sleep and reduce stress. It second version, due out this spring, attaches to the back of the neck instead of the head….

Several startups’ devices rely on sending electric pulses into the brain, a process called tDCS that hasn’t been approved for medical use in the U.S. While that stimulation has been found safe in a laboratory environment, the benefits in consumer devices are unclear because of a lack of independent studies, according to Rachel Wurzman, a researcher at the University of Pennsylvania’s Laboratory for Cognition and Neural Stimulation….

Startup Halo Neuroscience’s headset aims to improve athletic performance. The device sends electric fields into the brain’s motor cortex, creating a state of “hyperplasticity” which, when combined with athletic training, helps the brain more quickly build circuitry to interact with muscles, improving technique and explosiveness, said co-founder and Chief Executive Daniel Chao.

Users wear the $749 device, which looks like a pair of headphones, for 20 minutes before a workout. The San Francisco company has raised $9 million from Lux Capital, Andreessen Horowitz, Jazz Venture Partners, SoftTech VC and Xfund. Its athlete-endorsers include Demario Davis of the Cleveland Browns and T.J. Carrie of the Oakland Raiders.

Halo has focused on professional athletes but is targeting consumers who are performance athletes or enthusiasts, as opposed to casual athletes, said Mr. Chao, who previously worked at a medical-device startup that used electric stimulation to treat epilepsy….

While the use of brain stimulation is based on genuine science, it doesn’t necessarily back up marketing by consumer brands, said Marom Bikson, a professor of biomedical engineering at the City College of New York, who has done studies on Thync and co-founded medical-device startup Soterix Medical.

“There’s unquestionably scientific studies done in controlled environments that suggest that tDCS can change cognition and change how people think or can change learning,” Mr. Bikson said. “Some claims may be made by some companies that are maybe more advanced than where a lot of the scientists may be comfortable.”

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Neural Engineering
New paper: Model of ECT

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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Neural Engineering
New Paper: Mechanisms of tDCS and dose response

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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Neural Engineering
Lucas Parra lectures at CCNY – Feb 9

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.

Neural Engineering
New Paper- Human cochlear hydrodynamics: high-resolution μCT-based model

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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Neural Engineering
New Paper: Minimal heating at the Skin surface during transcranial direct current stimulation (tDCS)

Khadka N, Zannou AL, Zunura F,  Truong DQ,  Dmochowski J, Bikson M
______________________________________
Download PDF Published in Neuromodulation  DOI

Abstract

Objective: To assess if transcranial direct current stimulation (tDCS) produces a temperature change at the skin surface, if any change is stimulation polarity (anode or cathode) specific, and the contribution of passive heating (joule heat) or blood flow on such change.

Material and Methods: Temperature differences (ΔTs) in an agar phantom study and an in vivo study (forearm stimulation) including 20 volunteers with both experimental measures and finite element method (FEM) multiphysics prediction (current flow and bioheat) models of skin comprising three tissue layers (epidermis, dermis, and subcutaneous layer with blood perfusion) or of the phantom for active stimulation and control cases were compared. Temperature was measured during pre, post, and stimulation phases for both phantom and subject’s forearms using thermocouples.

Results: In the phantom, ΔT under both anode and cathode, compared to control, was not significantly different and less than 0.1°C. Stimulation of subjects resulted in a gradual increase in temperature under both anode and cathode electrodes, compared to control (at t = 20 min: ΔTanode = 0.9°C, ΔTcathode = 1.1°C, ΔTcontrol = 0.05°C). The FEM phantom model predicted comparable maximum ΔT of 0.27°C and 0.28°C (at t = 20 min) for the control and anode/cathode cases, respectively. The FEM skin model predicted a maximum ΔT at t = 20 min of 0.98°C for control and 1.36°C under anode/cathode electrodes.

Conclusions: Taken together, our results indicate a moderate and nonhazardous increase in temperature at the skin surface during 2 mA tDCS that is independent of polarity, and results from stimulation induced blood flow rather than joule heat.

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Neural Engineering
Two new papers on cellular mechanisms of tDCS

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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Neural Engineering
New paper: Cerebellar tDCS post-Stroke

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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Neural Engineering
Dr. Bikson chairs NYC Neuromodulation 2017 – Jan 13-15

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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Neural Engineering
New paper: Cerebellar tDCS post-Stroke

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

Journal Link

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Neural Engineering
News paper on tDCS and Post-Stroke Aphasia

Use of Computational Modeling to Inform tDCS Electrode Montages for the Promotion of Language Recovery in Post-stroke Aphasia.

Galletta EE, Cancelli A, Cottone C, Simonelli I, Tecchio F, Bikson M, Marangolo P.
Brain Stimul. 2015 Nov-Dec;8(6):1108-15. doi: 10.1016/j.brs.2015.06.018.

Download PDF

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Neural Engineering
New Paper: Transcranial direct current stimulation transiently increases the blood-brain barrier solute permeability in vivo

Shin D, Khadka N, Fan J, Bikson M, Fu B. 2016
___________________________________________
Download: PDF published in  SPIE Medical Imaging– DOI

Abstract
Transcranial Direct Current Stimulation (tDCS) is a non-invasive electrical stimulation technique investigated for a broad range of medical and performance indications. Whereas prior studies have focused exclusively on direct neuron polarization, our hypothesis is that tDCS directly modulates endothelial cells leading to transient changes in blood-brain-barrier (BBB) permeability (P) that are highly meaningful for neuronal activity. For this, we developed state-of-the-art imaging and animal models to quantify P to various sized solutes after tDCS treatment. tDCS was administered using a constant current stimulator to deliver a 1mA current to the right frontal cortex of rat (approximately 2 mm posterior to bregma and 2 mm right to sagittal suture) to obtain similar physiological outcome as that in the human tDCS application studies. Sodium fluorescein (MW=376), or FITC-dextrans (20K and 70K), in 1% BSA mammalian Ringer was injected into the rat (SD, 250-300g) cerebral circulation via the ipsilateral carotid artery by a syringe pump at a constant rate of ~3 ml/min. To determine P, multiphoton microscopy with 800-850 nm wavelength laser was applied to take the images from the region of interest (ROI) with proper microvessels, which are 100-200 micron below the pia mater. It shows that the relative increase in P is about 8-fold for small solute, sodium fluorescein, ~35-fold for both intermediate sized (Dex-20k) and large (Dex-70k) solutes, 10 min after 20 min tDCS pretreatment. All of the increased permeability returns to the control after 20 min post treatment. The results confirmed our hypothesis.

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Neural Engineering
Seminar on FDA: Dr. Caicedo, Johnson & Johnson

Fall 2016 Seminar Series Fall 2016 Seminar Series Department of Biomedical Engineering Wednesday, Nov. 30 @ 3PM in Steinman Hall Rm 402

Patient-centric innovation intersection

Dr. Hugo Caicedo

Janssen-Johnson & Johnson Pharmaceutical R&D

Abstract: The current FDA-based roadmap to drug and product development as well as regulatory decision- making and labeling, is based on four Clinical outcome assessments (COAs): Patient-reported outcome (PRO) measures, Clinician-reported outcome (ClinRO) measures, Observer-reported outcome (ObsRO) measures, and Performance outcome (PerfO) measures. In general, COAs are used to determine whether or not a therapy has demonstrated a net clinical benefit in a disease or health condition, in other words COAs assess safety and efficacy of a therapy. Under these conditions, individuals are subjected to “adequate and well-controlled studies”. The gap, however, is that in real life patients, in their natural environments, are under neither adequate nor well-controlled conditions, which limits both our capacity to understand the patient experience and our ability to develop innovated & targeted healthcare solutions. Additionally, current highly homogeneous and randomized clinical trials (RCTs) do not shed light on patient adherence to those therapies; about 50% of the patients with chronic diseases do not comply with medication therapy. During my presentation, I will talk about how three paradigms (Real World Evidence (RWE), Digital Analytics and Design Thinking) can converge and form a model that I created, the “Patient-centric innovation intersection”, to enable actionable insights for the development of targeted healthcare solutions, with particular focus in Diabetes therapy adherence.

Biosketch: Dr. Hugo Caicedo is a scientist subject matter expert in microfluidics, biomedical engineering and consumer healthcare at Janssen-Johnson & Johnson Pharmaceutical R&D in the Philadelphia area. There, he conducts preclinical research on drug discovery as well as strategic design on healthcare innovation to translate relevant science and technology into high-value partnerships that enable differentiated healthcare solutions. Currently, he is also a scholar trainee at the Corporate Sustainability and Innovation program at Harvard University. Dr. Caicedo holds a B.S in Electronics Engineering from the Universidad del Valle (Cali-Colombia) and a Ph.D. in Biomedical Engineering from the University of Illinois at Chicago (UIC). He was the recipient of MIT, Bogazicy University, Antalya University (Turkey) and UniversitéPierre and Marie Curie (France) pre-doctoral fellowships as well as one Harvard-MIT/HST post-doctoral fellowship. Dr. Caicedo has multiple publications including several peer-reviewed papers, two book chapters and a provisional patent application. Additionally, he has been awarded more than 20 recognition awards including: 2011, Ph.D student, African Colombian of the year in academia; 2012, Mayor’s Civic Merit Medal of Cali given directly by the President of Colombia; 2012, Distinguished PhD Student speaker at the 3rd US-Turkey Advanced Study Institute on Global Healthcare Challenges; 2015, BMES4SUCCESS, highlighted by the US Biomedical Engineering Society, as one of three —and the only member from industry— successful earlier career members in biomedical engineering; and 2016 Honorable Speaker invitation at the Biotechnology World Convention in Sao Paulo, Brazil.

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Neural Engineering
Now Available for Download: Two chapters from Neuromodulation Textbook

Textbook of Neuromodulation
Principles, Methods and Clinical Applications

Springer. ISBN: 978-1-4939-1407-4 

 

Methods and Technologies for Low-Intensity Transcranial Electrical Stimulation: Waveforms, Terminology, and Historical Notes
Page 7-16. Berkan Guleyupoglu, Pedro Schestatsky, Felipe Fregni, Marom Bikson

PDF: 10-1007978-1-4939-1408-12

 

A Role of Computational Modeling in Customization of Transcranial Direct Current Stimulation for Susceptible Populations
Dennis Truong, Preet Minhas, Albert Mokrejs, Marom Bikson

PDF: 10-1007978-1-4939-1408-110

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Neural Engineering
New Paper (and cover): Semantic Processing in Primary Progressive Aphasia

Direct current stimulation over the anterior temporal areas boosts semantic processing in primary progressive aphasia.

Teichmann M, Lesoil C, Godard J, Vernet M, Bertrand A, Levy R, Dubois B, Lemoine L, Truong DQ, Bikson M, Kas A, Valero-Cabré A. Ann Neurol. 2016 Nov;80(5):693-707. doi: 10.1002/ana.24766.

Download PDF

Abstract: Objective: Noninvasive brain stimulation in primary progressive aphasia (PPA) is a promising approach. Yet, applied to single cases or insufficiently controlled small-cohort studies, it has not clarified its therapeutic value. We here address the effectiveness of transcranial direct current stimulation (tDCS) on the semantic PPA variant (sv-PPA), applying a rigorous study design to a large, homogeneous sv-PPA cohort. Methods: Using a double-blind, sham-controlled counterbalanced cross-over design, we applied three tDCS condi- tions targeting the temporal poles of 12 sv-PPA patients. Efficiency was assessed by a semantic matching task orthogonally manipulating “living”/”nonliving” categories and verbal/visual modalities. Conforming to predominantly left-lateralized damage in sv-PPA and accounts of interhemispheric inhibition, we applied left hemisphere anodal- excitatory and right hemisphere cathodal-inhibitory tDCS, compared to sham stimulation. Results: Prestimulation data, compared to 15 healthy controls, showed that patients had semantic disorders predomi- nating with living categories in the verbal modality. Stimulation selectively impacted these most impaired domains: Left- excitatory and right-inhibitory tDCS improved semantic accuracy in verbal modality, and right-inhibitory tDCS improved processing speed with living categories and accuracy and processing speed in the combined verbal 3 living condition. Interpretation: Our findings demonstrate the efficiency of tDCS in sv-PPA by generating highly specific intrasemantic effects. They provide “proof of concept” for future applications of tDCS in therapeutic multiday regimes, potentially driv- ing sustained improvement of semantic processing. Our data also support the hotly debated existence of a left temporal- pole network for verbal semantics selectively modulated through both left-excitatory and right-inhibitory brain stimulation.

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Neural Engineering