intensity- and frequency-specific effects of transcranial alternating current stimulation are explained by network
Zhihe Zhao1, Sina Shirinpour1, Harry Tran1
1Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America.
Journal of Neural Engineering
|March 26, 2024
Summary
Transcranial alternating current stimulation (tACS) effects are intensity- and frequency-dependent. Computational models reveal tACS non-linearly modulates neural oscillations, entraining neurons at higher intensities and specific frequencies.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Computational Biology
Background:
- Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique.
- tACS aims to entrain neural activity and alter neural oscillatory power.
- The precise mechanisms underlying tACS effects remain incompletely understood.
Purpose of the Study:
- To investigate the fundamental mechanisms of tACS.
- To explore how tACS modulates endogenous neural oscillations.
- To understand the intensity- and frequency-dependent effects of tACS on neuronal networks.
Main Methods:
- Developed a computational neuronal network model of pyramidal (PY) and inhibitory interneurons.
- Modeled tACS with human-achievable electric field strengths.
- Simulated intrinsic network activity and measured neural entrainment.
Main Results:
- tACS effects are non-linear and intensity-dependent.
- Low tACS intensities (<0.3 mV mm⁻¹) desynchronize neural firing.
- Higher tACS intensities (>0.3 mV mm⁻¹) entrain neurons to the electric field.
- Entrainment follows an Arnold tongue based on stimulation frequency.
- Neuronal networks can amplify tACS-induced entrainment.
- PY neurons are directly entrained and drive inhibitory neurons.
Conclusions:
- Provides a mechanistic framework for tACS effects on neuronal networks.
- Highlights the importance of intensity and frequency in tACS parameter selection.
- Crucial for optimizing tACS in cognitive neuroscience and clinical applications.
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