Relationship between neural activation and electric field distribution during deep brain stimulation

Area of Science:

• Neuroscience
• Biophysics
• Computational Modeling

Background:

• Deep brain stimulation (DBS) research commonly utilizes models and simulations.
• Simulated stimulation fields are often visualized using electric field isolevels or volumes of tissue activated (VTA).

Purpose of the Study:

• To evaluate the relationship between stimulation field strength (electric potential V, electric field E, and divergence of electric field ∇(2)V) and neural activation in DBS.
• To derive field thresholds for approximating neural activation in DBS models.

Main Methods:

• Developed and coupled axon cable models to three-dimensional (3-D) finite-element DBS models.
• Derived field thresholds (VT, ET, and ∇(2)VT) at the site of neural activation across varying stimulation amplitudes, pulse widths, and axon diameters.

Main Results:

• Thresholds for electric potential (VT) and divergence of electric field (∇(2)VT) were highly dependent on stimulation amplitude.
• Electric field (ET) thresholds showed approximate independence from amplitude for larger axons.
• Established field strength thresholds for neural activation in DBS.

Conclusions:

• The derived activation field strength thresholds can potentially approximate the VTA in model-based DBS investigations.
• This method may reduce the necessity for computationally intensive axon models in future DBS research.