Novel flexible cap for application of transcranial electric stimulation: a usability study

Mapping Intimacies ◽

10.21203/rs.3.rs-19650/v1 ◽

2020 ◽

Author(s):

Alexander Hunold ◽

Daniela Ortega ◽

Klaus Schellhorn ◽

Jens Haueisen

Keyword(s):

Healthy Volunteers ◽

Electric Stimulation ◽

Electrode Configuration ◽

Electrode Position ◽

Usability Study ◽

Subjective Evaluations ◽

Transcranial Electric Stimulation ◽

New Applications

Abstract BackgroundAdvances in transcranial electric stimulation (TES) were hampered by the conventional rubber electrodes manually attached to the head with rubber bands. This procedure limited montages to a few electrodes, was error prone with respect to electrode configurations and was burdensome for participants and operators. A newly developed flexible cap with integrated textile stimulation electrodes was compared to the conventional setup of rubber electrodes fixated by rubber bands, with respect to usability and reliability. Two operators applied both setups to twenty healthy volunteers participating in the study. Electrode position and impedance measures as well as subjective evaluations from participants and operators were obtained throughout the stimulation sessions. ResultsOur results demonstrated the superiority of the flexible cap by means of significantly higher electrode configuration reproducibility and a more efficient application. Both, operators and volunteers evaluated the flexible cap as easier to use and more comfortable to wear when compared to the conventional setup. ConclusionIn conclusion, the new cap improves existing and opens new applications scenarios for TES.

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Bioelectromagnetism in Human Brain Research: New Applications, New Questions

The Neuroscientist ◽

10.1177/10738584211054742 ◽

2021 ◽

pp. 107385842110547

Author(s):

Joachim Gross ◽

Markus Junghöfer ◽

Carsten Wolters

Keyword(s):

Transcranial Magnetic Stimulation ◽

Human Brain ◽

Clinical Studies ◽

Electric Stimulation ◽

Magnetic Stimulation ◽

Common Ground ◽

Brain Research ◽

Fundamental Principle ◽

Transcranial Electric Stimulation ◽

New Applications

Bioelectromagnetism has contributed some of the most commonly used techniques to human neuroscience such as magnetoencephalography (MEG), electroencephalography (EEG), transcranial magnetic stimulation (TMS), and transcranial electric stimulation (TES). The considerable differences in their technical design and practical use give rise to the impression that these are quite different techniques altogether. Here, we review, discuss and illustrate the fundamental principle of Helmholtz reciprocity that provides a common ground for all four techniques. We show that, more than 150 years after its discovery by Helmholtz in 1853, reciprocity is important to appreciate the strengths and limitations of these four classical tools in neuroscience. We build this case by explaining the concept of Helmholtz reciprocity, presenting a methodological account of this principle for all four methods and, finally, by illustrating its application in practical clinical studies.

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Human Sensation of Transcranial Electric Stimulation

Scientific Reports ◽

10.1038/s41598-019-51792-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Fan-Gang Zeng ◽

Phillip Tran ◽

Matthew Richardson ◽

Shuping Sun ◽

Yuchen Xu

Keyword(s):

Auditory Nerve ◽

Electric Stimulation ◽

Stimulus Frequency ◽

Low Frequency ◽

Electrode Position ◽

Computer Interfaces ◽

Transcranial Alternating Current Stimulation ◽

Transcranial Electric Stimulation ◽

Somatic Sensation ◽

Deep Brain

Abstract Noninvasive transcranial electric stimulation is increasingly being used as an advantageous therapy alternative that may activate deep tissues while avoiding drug side-effects. However, not only is there limited evidence for activation of deep tissues by transcranial electric stimulation, its evoked human sensation is understudied and often dismissed as a placebo or secondary effect. By systematically characterizing the human sensation evoked by transcranial alternating-current stimulation, we observed not only stimulus frequency and electrode position dependencies specific for auditory and visual sensation but also a broader presence of somatic sensation ranging from touch and vibration to pain and pressure. We found generally monotonic input-output functions at suprathreshold levels, and often multiple types of sensation occurring simultaneously in response to the same electric stimulation. We further used a recording circuit embedded in a cochlear implant to directly and objectively measure the amount of transcranial electric stimulation reaching the auditory nerve, a deep intercranial target located in the densest bone of the skull. We found an optimal configuration using an ear canal electrode and low-frequency (<300 Hz) sinusoids that delivered maximally ~1% of the transcranial current to the auditory nerve, which was sufficient to produce sound sensation even in deafened ears. Our results suggest that frequency resonance due to neuronal intrinsic electric properties need to be explored for targeted deep brain stimulation and novel brain-computer interfaces.

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