Effects of transcranial Direct Current Stimulation (tDCS) on cortical activity: a computational modeling study

Area of Science:

• Neuroscience
• Computational Neuroscience
• Computational Modeling

Background:

• Transcranial Direct Current Stimulation (tDCS) is known to modulate brain rhythms, but its precise neural mechanisms are not fully understood.
• Investigating the local effects of tDCS on neuronal populations requires sophisticated models that capture complex neural dynamics.

Purpose of the Study:

• To develop and validate a novel computational neural mass model of the cerebral cortex.
• To investigate the local effects of anodal and cathodal tDCS on neuronal populations using the model.
• To elucidate the mechanisms by which tDCS influences neural activity and evoked potentials.

Main Methods:

• Elaboration of a neural mass model incorporating pyramidal cells and inhibitory interneurons with slow and fast synaptic kinetics.
• Adjustment of model parameters to accurately reproduce in-vivo evoked potentials (EPs) recorded from the rabbit somatosensory cortex.
• Simulation of EPs under control, anodal, and cathodal tDCS conditions.

Main Results:

• Inclusion of a feed-forward inhibition mechanism was crucial for accurately simulating EP peaks and latencies.
• Simulated EPs more closely matched experimental data when interneurons were affected by the applied tDCS fields.
• Anodal tDCS simulations yielded more realistic EPs when pyramidal cells were depolarized and slow/fast interneurons exhibited specific polarization changes.

Conclusions:

• The computational model provides insights into the local effects of tDCS on cortical neuronal populations.
• Interneurons play a significant role in mediating the effects of tDCS on neural activity.
• Neuronal geometry may influence how interneurons respond to externally applied electric fields, impacting tDCS efficacy.