Source localization in the spinal cord: a modeling study

Intraspinal microstimulation of the spinal cord is being investigated as a means of eliciting coordinated motor responses for restoration of function. However, detailed maps of the neuroanatomy of the human spinal cord are lacking, and thus it is not clear where electrodes should be implanted. We are developing a method to map motor nuclei in the spinal cord using potentials recorded from the surface of the spinal cord and model-based optimization. We modeled this localization approach using an analytical volume conductor of the spinal cord and a two-step optimization algorithm. As a first approximation, neural activity was modeled as a current point source within the gray matter region of the volume conductor. Several recording arrays with various numbers of electrodes and electrode densities were implemented in the model. The results of the study indicate that the reconstruction approach is feasible, even in the presence of noise, using 16 appropriately positioned recording electrodes.