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Stoney vs. Histed: Quantifying the spatial effects of intracortical microstimulation
Karthik Kumaravelu1, Joseph Sombeck2, Lee E Miller3
1Department of Biomedical Engineering, Duke University, Durham, NC, USA.
Brain Stimulation
|December 3, 2021
Summary
Computational modeling reveals that increasing intracortical microstimulation (ICMS) intensity expands the area where action potentials are initiated, while the density of activated neurons increases within a stable somatic activation volume.
Area of Science:
- Neuroscience
- Computational modeling
- Neural engineering
Background:
- Intracortical microstimulation (ICMS) is crucial for mapping neural circuits and restoring sensory functions.
- Conflicting findings exist regarding how ICMS intensity affects spatial activation volumes versus neuronal activation density.
Purpose of the Study:
- To computationally model and quantify the spatial effects of ICMS intensity.
- To reconcile the divergent conclusions of previous studies on ICMS spatial effects.
Main Methods:
- Developed a biophysically-based computational model of a cortical column.
- Simulated single pulses and short trains of ICMS.
- Quantified neuronal activation volume and density as a function of stimulation intensity.
Main Results:
- Somatic activation primarily occurred via antidromic axonal propagation, not direct somatic/dendritic activation.
- The volume of action potential initiation increased with ICMS amplitude.
- Somatic activation volume showed minimal increase, while activation density within this volume rose with intensity.
Conclusions:
- Reconciles paradoxical findings by showing ICMS intensity expands initiation volume (Stoney) but increases density within a stable somatic volume (Histed).
- Highlights that action potential initiation volume and somatic activation volume/density respond differently to ICMS intensity.
