Paper Info
Title
Targeting alpha-band oscillations in a cortical model with amplitude-modulated high-frequency transcranial electric stimulation.
Abstract
Non-invasive brain stimulation to target specific network activity patterns, e.g. transcranial alternating current stimulation (tACS), has become an essential tool to understand the causal role of neuronal oscillations in cognition and behavior. However, conventional sinusoidal tACS limits the ability to record neuronal activity during stimulation and lacks spatial focality. One particularly promising new tACS stimulation paradigm uses amplitude-modulated (AM) high-frequency waveforms (AM-tACS) with a slow signal envelope that may overcome the limitations. Moreover. AM-tACS using high-frequency carrier signals is more tolerable than conventional tACS, e.g. in terms of skin irritation and occurrence of phosphenes, when applied at the same current intensities (e.g. 1–2 mA). Yet, the fundamental mechanism of neuronal target-engagement by AM-tACS waveforms has remained unknown. We used a computational model of cortex to investigate how AM-tACS modulates endogenous oscillations and compared the target engagement mechanism to the case of conventional (unmodulated) low-frequency tACS. Analysis of stimulation amplitude and frequency indicated that cortical oscillations were phase-locked to the envelope of the AM stimulation signal, which thus exhibits the same target engagement mechanism as conventional (unmodulated) low frequency tACS. However, in the computational model substantially higher current intensities were needed for AM-tACS than for low-frequency (unmodulated) tACS waveforms to achieve pronounced phase synchronization. Our analysis of the carrier frequency suggests that there might be a trade-off between the use of high-frequency carriers and the stimulation amplitude required for successful entrainment. Together, our computational simulations support the use of slow-envelope high frequency carrier AM waveforms as a tool for noninvasive modulation of brain oscillations. More empirical data will be needed to identify the optimal stimulation parameters and to evaluate tolerability and safety of both, AM- and conventional tACS.
Year
DOI
Venue
2018
10.1016/j.neuroimage.2018.02.005
NeuroImage
Keywords
Field
DocType
Brain stimulation,Computer simulation,Target engagement,Transcranial alternating current stimulation,tACS,Amplitude modulation
Phosphene,Neuroscience,Premovement neuronal activity,Brain stimulation,Transcranial alternating current stimulation,Phase synchronization,Psychology,Cognitive psychology,Modulation,Amplitude,Stimulation
Journal
Volume
ISSN
Citations 
173
1053-8119
4
PageRank 
References 
Authors
0.51
6
4
Name
Order
Citations
PageRank
Ehsan Negahbani150.87
Florian H. Kasten250.87
Christoph Herrmann337344.21
Flavio Fröhlich492.62