A strategy for mapping biophysical to abstract neuronal network models applied to primary visual cortex

Abstract

A fundamental challenge for the theoretical study of neuronal networks is to make the link between complex biophysical models based directly on experimental data, to progressively simpler mathematical models that allow the derivation of general operating principles. We present a strategy that successively maps a relatively detailed biophysical population model, comprising conductance-based Hodgkin-Huxley type neuron models with connectivity rules derived from anatomical data, to various representations with fewer parameters, finishing with a firing rate network model that permits analysis. We apply this methodology to primary visual cortex of higher mammals, focusing on the functional property of stimulus orientation selectivity of receptive fields of individual neurons. The mapping produces compact expressions for the parameters of the abstract model that clearly identify the impact of specific electrophysiological and anatomical parameters on the analytical results, in particular as manifested by specific functional signatures of visual cortex, including input-output sharpening, conductance invariance, virtual rotation and the tilt after effect. Importantly, qualitative differences between model behaviours point out consequences of various simplifications. The strategy may be applied to other neuronal systems with appropriate modifications.

Response retention and apparent motion effect in visual cortex models

“…This elongation creates an orientation bias in cortical responses. Since cortical neurons that receive thalamic inputs with similar orientation bias are localized in columns, the local interactions, structured by Gaussian connectivity, lead to intracortical sharpening of the orientation tuning [ 24 , 27 ]. This sharpening is not only driven by excitation but also by inhibition and voltage-gated mechanisms including shunting.…”