Journal of Vision - Comparison of contrast-response functions from multifocal visual-evoked potentials (mfVEPs) and functional MRI responses, by Park, Zhang, Ferrera, Hirsch, & Hood

Jason C. Park	Department of Psychology, Columbia University, New York, NY, USA
Xian Zhang	Department of Radiology, and Psychology, Columbia University, New York, NY, USA
John Ferrera	Functional MRI Research Center, Columbia University, Clinical Neuropsychology Program, CUNY Graduate Center, New York, NY, USA
Joy Hirsch	Departments of Radiology, Psychology, and Neuroscience, Functional MRI Research Center, Columbia University, New York, NY, USA
Donald C. Hood	Departments of Psychology and Ophthalmology, Columbia University, New York, NY, USA

Contrast response functions (CRFs) from multifocal visual-evoked potential (mfVEP) and BOLD fMRI responses were obtained using the same stimuli to test the hypothesis of a linear relationship between the mfVEP and BOLD fMRI responses. Monocular mfVEP and BOLD fMRI responses were obtained using an 8° in diameter, dartboard pattern stimulus with reversing checkerboards. Six contrast conditions (4%, 8%, 16%, 32%, 64%, and 90%) were run. The mfVEP, largely generated in V1, was compared to the BOLD fMRI signal from V1 and extrastriate cortex. Retinotopic maps of each subject were acquired and used to localize the V1 area. For all subjects, the CRFs for the mfVEPs and BOLD fMRI responses showed good agreement, suggesting that they both share the same functional relationship with underlying neural activity. In particular, this result is consistent with the assumption that the relationship between the BOLD response and underlying neural activity is linear, although the particular linear model proposed by D. J. Heeger, A. C. Huk, W. S. Geisler, and D. G. Albrecht (2000) does not fit the results.