A biophysical model linking cortical scalar potentials and polarization waves to slow traveling activity in vision

Recent experimental studies indicate that visual cognition is accompanied by slowly propagating biophysical traveling waves in cortical tissue. Here, we propose that polarization waves within the visual cortex provide the biophysical basis for the observed slowly propagating traveling waves. For this, we first compute the propagation speed of scalar potential fields generated by impressed ionic currents in primary visual cortex using a theoretically derived telegraph-type model equation. On the basis of the linear convolution framework, we then show that the scalar potential field $$\varvec{\phi\:}(\varvec{x},\varvec{t})$$ and the polarization wave $$\varvec{P}(\varvec{x},\varvec{t})$$, arising from slowly oscillating neuronal dipoles, propagate with the same velocity. Remarkably, the predicted speed is consistent with the independently estimated propagation speed of an effective cortical modulation wave (~ 1.5 cm/s). Since each parallel retinal/LGN/geniculocortical pathway gathers signals from more than a hundred photoreceptors, the resulting response is likely to cover a range of effective cortical wave numbers. In this multi-$$\varvec{k}$$ regime, we show that dispersive spreading naturally emerges over time, which may reduce cross-channel interference and help stabilize perceptual processing.