Electric Field Dynamics in the Brain During Multi-Electrode Transcranial Electric Stimulation

Alekseichuk, Ivan; Falchier, Arnaud; Linn, Gary; Xu, Ting; Milham, Michael P.; Schroeder, Charles E.; Opitz, Alexander

doi:10.1101/340224

Cited by 8 publications

(6 citation statements)

References 58 publications

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“…Future studies systematically manipulating the TACS parameter range (frequency, electric field orientation, duration) will be important to identify the most effective stimulation parameters for immediate and lasting physiological effects. These studies will be facilitated by our increasing understanding of the underlying biophysics of TACS 12,53 and sophisticated models to predict intracranial electric fields 41 .…”

Section: Discussionmentioning

confidence: 99%

Dose-Dependent Effects of Transcranial Alternating Current Stimulation on Spike Timing in Awake Nonhuman Primates

Johnson

Alekseichuk

Krieg

et al. 2019

Preprint

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Weak extracellular electric fields can influence spike timing in neural networks. Approaches to impose such fields on the brain in a noninvasive manner have high potential for novel treatments of neurological and psychiatric disorders. One of these methods, transcranial alternating current stimulation (TACS), is hypothesized to affect spike timing and cause neural entrainment. However, the conditions under which these effects occur in-vivo are unknown. Here, we show that TACS modulates spike timing in awake nonhuman primates (NHPs) in a dose-dependent fashion. Recording single-unit activity from pre-and post-central gyrus regions in NHPs during TACS, we found that a larger population of neurons became entrained to the stimulation waveform for higher stimulation intensities. Performing a cluster analysis of changes in interspike intervals, we identified two main types of neural responses to TACS -increased burstiness and phase entrainment. Our results demonstrate the ability of TACS to affect spike-timing in the awake primate brain and identify fundamental neural mechanisms. Concurrent electric field recordings demonstrate that spike-timing changes occur with stimulation intensities readily achievable in humans. These results suggest that novel TACS protocols tailored to ongoing brain activity may be a potent tool to normalize spike-timing in maladaptive brain networks and neurological disease.

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Section: Discussionmentioning

confidence: 99%

Dose-Dependent Effects of Transcranial Alternating Current Stimulation on Spike Timing in Awake Nonhuman Primates

Johnson

Alekseichuk

Krieg

et al. 2019

Preprint

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“…Monkey: We used an individual FEM model of a normal adult male capuchin monkey (from Alekseichuk et al, 2018). In short, structural MR imaging (T1 and T2) was performed at the Nathan Kline Institute for Psychiatric Research, USA with approval of the local Institutional Animal Care and Use Committee.…”

Section: Fem Modelsmentioning

confidence: 99%

Comparative Modeling of Transcranial Magnetic and Electric Stimulation in Mouse, Monkey, and Human

Alekseichuk

Mantell

Shirinpour

et al. 2018

Preprint

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Transcranial magnetic stimulation (TMS) and transcranial electric stimulation (TES) are increasingly popular methods to noninvasively affect brain activity. However, their mechanism of action and doseresponse characteristics remain under active investigation. Translational studies in animals play a pivotal role in these efforts due to a larger neuroscientific toolset enabled by invasive recordings. In order to translate knowledge gained in animal studies to humans, it is crucial to generate comparable stimulation conditions with respect to the induced electric field in the brain. Here, we conduct a finite element method (FEM) modeling study of TMS and TES electric fields in a mouse, capuchin monkey, and human model.We systematically evaluate the induced electric fields and analyze their relationship to head and brain anatomy. We find that with increasing head size, TMS-induced electric field strength first increases and then decreases according to a two-term exponential function. TES-induced electric field strength strongly decreases from smaller to larger specimen with up to 100x fold differences across species. Our results can serve as a basis to compare and match stimulation parameters across studies in animals and humans. KEYWORDSTranscranial magnetic stimulation; transcranial electric stimulation; finite element modeling; animal models HIGHLIGHTS • Translational research in brain stimulation should account for large differences in induced electric fields in different organisms • We simulate TMS and TES electric fields using anatomically realistic finite element models in three species: mouse, monkey, and human• TMS with a 70 mm figure-8 coil creates an approximately 2-times weaker electric field in a mouse brain than in monkey and human brains, where electric field strength is comparable • Two-electrode TES creates an approximately 100-times stronger electric field in a mouse brain and 3.5-times stronger electric field in a monkey brain than in a human brain

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“…This previous experimental work, both in vivo and in silico , has yielded scarce evidence of asymmetrical travelling wave propagation or reliable wave generation analogous to that reported here. To the extent that previous work has focused on travelling wave propagation initiated by stimulation 42 , these studies examined stimulation through the skull and meninges, and are thus not directly comparable to this model of intracranial stimulation of the cortical surface. Many computational models exist that model the effects of stimulation on the brain, including some that have constructed Hodgkin-Huxley microcircuits 43,44 and modeled cortical surface stimulation 45 .…”

Section: Discussionmentioning

confidence: 99%

Multielectrode Cortical Stimulation Selectively Induces Unidirectional Wave Propagation

A¹,

Z²,

Golden³

et al. 2020

Preprint

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Cortical stimulation is emerging as an experimental tool in basic research and a promising therapy for a range of neuropsychiatric conditions. As multielectrode arrays enter clinical practice, the possibility of using spatiotemporal patterns of electrical stimulation to induce desired physiological patterns has become theoretically possible, but in practice can only be implemented by trial-and-error because of a lack of predictive models. Experimental evidence increasingly establishes travelling waves as fundamental to cortical information-processing, but we lack understanding how to control wave properties despite rapidly improving technologies. This study uses a hybrid biophysical-anatomical and neural-computational model to predict and understand how a simple pattern of cortical surface stimulation could induce directional traveling waves in excitatory cells via asymmetric activation of inhibitory cells. The ability to induce such activity via stimulation suggests the potential to treat a broad range of cognitive disorders and to shed light on the electrical nature of cortical functioning.

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Electric Field Dynamics in the Brain During Multi-Electrode Transcranial Electric Stimulation

Cited by 8 publications

References 58 publications

Dose-Dependent Effects of Transcranial Alternating Current Stimulation on Spike Timing in Awake Nonhuman Primates

Dose-Dependent Effects of Transcranial Alternating Current Stimulation on Spike Timing in Awake Nonhuman Primates

Comparative Modeling of Transcranial Magnetic and Electric Stimulation in Mouse, Monkey, and Human

Multielectrode Cortical Stimulation Selectively Induces Unidirectional Wave Propagation

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