Transcranial Alternating Current Stimulation with Sawtooth Waves: Simultaneous Stimulation and EEG Recording

Area of Science:

• Neuroscience
• Neuromodulation
• Brain Stimulation Techniques

Background:

• Transcranial alternating current stimulation (tACS) traditionally uses sinusoidal waveforms.
• Modern tACS devices can generate arbitrary waveforms, but systematic exploration is lacking.
• Investigating novel tACS waveforms may reveal superior or complementary effects to sinusoidal stimulation.

Purpose of the Study:

• To investigate the effects of sawtooth wave tACS on individual alpha power.
• To compare the impact of positive and negative ramp sawtooth waves on neural activity.
• To assess the potential of non-sinusoidal waveforms for tACS applications.

Main Methods:

• tACS was applied using positive and negative ramp sawtooth waveforms.
• Electroencephalogram (EEG) was used to measure alpha power.
• Sham stimulation was used as a control condition.
• Alpha oscillations were analyzed during and after stimulation.

Main Results:

• Positive ramp sawtooth tACS significantly enhanced alpha power during stimulation compared to sham (p < 0.01).
• Negative ramp sawtooth tACS did not significantly affect alpha power.
• No significant after-effect on alpha power was observed for either sawtooth or sinusoidal tACS.

Conclusions:

• Positive ramp sawtooth waveform tACS is a viable method for enhancing alpha power.
• The direction of current flow in tACS may influence its efficacy.
• Further research into non-sinusoidal tACS waveforms is warranted to optimize neuromodulation.