A Two-Stage Cascade Model of BOLD Responses in Human Visual Cortex

Kendrick N. Kay, Jonathan Winawer, Ariel Rokem, Aviv Mezer, Brian A. Wandell

Research output: Contribution to journalArticle

Abstract

Visual neuroscientists have discovered fundamental properties of neural representation through careful analysis of responses to controlled stimuli. Typically, different properties are studied and modeled separately. To integrate our knowledge, it is necessary to build general models that begin with an input image and predict responses to a wide range of stimuli. In this study, we develop a model that accepts an arbitrary band-pass grayscale image as input and predicts blood oxygenation level dependent (BOLD) responses in early visual cortex as output. The model has a cascade architecture, consisting of two stages of linear and nonlinear operations. The first stage involves well-established computations-local oriented filters and divisive normalization-whereas the second stage involves novel computations-compressive spatial summation (a form of normalization) and a variance-like nonlinearity that generates selectivity for second-order contrast. The parameters of the model, which are estimated from BOLD data, vary systematically across visual field maps: compared to primary visual cortex, extrastriate maps generally have larger receptive field size, stronger levels of normalization, and increased selectivity for second-order contrast. Our results provide insight into how stimuli are encoded and transformed in successive stages of visual processing.

Original languageEnglish (US)
Article numbere1003079
JournalPLoS computational biology
Volume9
Issue number5
DOIs
StatePublished - May 2013

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Modeling and Simulation
  • Ecology
  • Molecular Biology
  • Genetics
  • Cellular and Molecular Neuroscience
  • Computational Theory and Mathematics

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    Kay, K. N., Winawer, J., Rokem, A., Mezer, A., & Wandell, B. A. (2013). A Two-Stage Cascade Model of BOLD Responses in Human Visual Cortex. PLoS computational biology, 9(5), [e1003079]. https://doi.org/10.1371/journal.pcbi.1003079