Intensity- and frequency-specific effects of transcranial alternating current stimulation are explained by network...

Area of Science:

• Computational Neuroscience
• Neuroimaging and Stimulation Techniques

Background:

• Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique used to modulate neural activity and oscillatory power.
• The precise mechanisms underlying tACS effects on neural networks remain incompletely understood, hindering optimal application in cognitive and clinical neuroscience.

Approach:

• Developed a computational neuronal network model simulating two-compartment pyramidal neurons and inhibitory interneurons to mimic cortical circuits.
• Modeled tACS with physiologically relevant electric field strengths to investigate neural entrainment to ongoing endogenous oscillations.
• Simulated intrinsic network activity and analyzed neural firing patterns under varying tACS intensities and frequencies.

Key Points:

• tACS exhibits non-linear, intensity-dependent effects: low intensities (<0.3 mV/mm) desynchronize neural firing, while higher intensities entrain neurons to the electric field.
• Neural entrainment to tACS follows an Arnold tongue, indicating frequency-dependent effects on cortical oscillations.
• Neuronal networks can amplify tACS-induced entrainment through excitation-inhibition balance, with pyramidal neurons directly entrained and driving inhibitory neurons.

Conclusions:

• The study provides a mechanistic framework for understanding the intensity- and frequency-specific effects of oscillating electric fields on neuronal networks.
• Findings are crucial for selecting rational stimulation parameters for tACS in cognitive research and clinical interventions.
• The computational model elucidates how tACS modulates endogenous neural oscillations and highlights the role of network dynamics in tACS efficacy.