BOLD response to images formed from random placement of Gabor patches.

This project was motivated by the following question: is specification of RMS contrast and spatial frequency content sufficient to predict the V1 BOLD response? A simple thought experiment, illustrated by the images shown below (which all have the same RMS contrast and spatial frequency content), gives the answer - no! The problem is in the posing of the question: global contrast and global BOLD response are the wrong questions to be asking in V1. In V1, it's all about local contrast.

low density 1 cpd Gabor patches     high density 1 cpd Gabors     scrambled image (1 cpd noise)

At VSS 2004 I presented preliminary work testing our ability to predict and quantify local BOLD responses to local image features (abstract published in JOV). This line of research has progressed in two directions. One direction is my obsession with localized responses to individual Gabor patches, with and without near neighbors. The other direction is a collaboration with Katja Doerschner, looking at V1 responses to positive and negative contrast. Part of this experiment manipulates the density of the patterns (VSS 2009).





tutorials & data

hall of shame

© 2008, C. A. Olman
date of last update: June 25, 2011