How the Cortex generates a sparse and reliable code

Does the cortex use a dense code in which neurons discharge to lots of stimuli (e.g. like a photoreceptor) or is the code more sparse, with spikes representing more rare events? A related question is: how energy efficient is the cortex? Do cortical neurons generate high rates of activity or are they more quiet than active? (A sparse code is typically associated with fewer spikes over prolonged periods.)

Introduction

Fig. 1. Here we examine the cellular mechanisms of sparseness, reliability, and precision in visual cortical neurons by recording intracellularly from visual cortical neurons in V1 from anesthetized animals while presenting natural scenes on a computer monitor.

This seminar is based upon a study published here: Haider, B., Krause, M.R., Duque, A., Yu, Y., Touryan, J., Mazer, J.A., McCormick, D.A. (2010) Synaptic and network mechanisms of sparse and reliable visual cortical activity during nonclassical receptive field stimulation. Neuron, 65: 107-121.

This work was done in collaboration with the laboratory of Jamie Mazer at Yale.