Computed potentials of cortically arranged populations of neurons

Abstract

The distribution of electric potential was computed for simplified neuronal populations arranged as idealized cortics: a closed spherical cortex composed of 50,000 synchronously active neurons, and several open cortices designated as a punctured sphere, a hemisphere, and a cap. The closed, radially symmetrical field (millivolt magnitudes) of the closed cortex, contrasted with the approximately dipolar field (microvolt magnitudes) of a single neuron having 1 cylindrical dendrite. The open cortices produced fields which had much more in common with the closed sphere case than with the single neuron: within each active cortical region the equipotential surfaces remained essentially spherical (with the gradient of potential essentially radial); relative to a distant reference, these potentials were shifted (and slightly reduced) in good agreement with the potential divider model (lumped parameter circuit) which provides a simple relation between the potentials in the closed cortex and those in an open cortex. Applications [to the rabbit] and modifications were discussed.