Chapter 14 - Exploring Cortical Microcircuits: A Combined Anatomical, Physiological, and Computational Approach

Abstract

This chapter discusses a simple model of neurons that can abstract the most important anatomical and physiological properties required for exploring cortical circuits. The diversity of neuron types in the visual cortex to three essential types: layer 3 small pyramidal neurons, layer 5 large pyramidal neurons, and nonspiny inhibitory neurons. These neurons are combined in a canonical microcircuit. Microcircuit modeling is a fine form of explanation and prediction. The chapter also presents the evidence derived from experimental data and computer simulations showing that the predominant communication within the cortex is among the excitatory pyramidal neurons, which form a recurrent cortical amplifier. Simulations with abstract neurons were used to examine the possibility that inhibition of the axon initial segment might provide an alternative source of strong inhibition. Inhibition functions both to control access to this amplifier and control the gain of the neurons to suprathreshold excitatory inputs. The chapter also explains the way feature selectivity operates in such a system and contrasts it with the Barlow–Levick model of directional selectivity.