Decoding the neural representation of size using multivariate pattern analyses and high density electroencephalography

Abstract

The perception of object size is not a simple process. The retinal size of an object scales with distance to the observer, and human beings lack a dedicated system for accurately measuring object distance outside a limited range. Here, we seek to answer three general questions about size perception: Which regions of visual cortex represent the perceived size of an object? What are the feedforward and feedback interactions that underlie the neural representation of object size? What are the domain specific and domain general characteristics of the neural representation of object size? Previous research, using principally fMRI techniques, has indicated primary visual cortex (V1) as playing a primary role in representing perceived object size. Here we examine the neural representation of perceived size using High Definition Electroencephalography (HD EEG) and Multivariate Pattern Analysis (MVPA) techniques in an attempt to characterize the time course and localization of perceived size processing within the brain. We find that perceived size is represented throughout the visual system in a largely domain specific fashion, and that processing perceived size does not take place in a simple feedforward fashion originating in early visual areas.