Up
Previous
Next
Using natural images to study the relationship between the activity of
neural populations and the BOLD signal
Gregor Rainer, Mark Augath, Torsten Trinath and Nikos K. Logothetis
Max-Planck-Institute for Biological Cybernetics, Tübingen (Germany)
The relationship between the blood-oxygenation-level-dependent (BOLD)
signal measured using functional-magnetic-resonance-imaging (fMRI) and
the activity of neural populations remains incompletely understood.
The recording of BOLD activity in monkeys permits us to formulate
experimentally testable hypotheses about the relationship between
these signals. Here, we used parametric sets of images that were
generated by interpolation between natural images and noise patterns
matched for luminance and spatial frequency. We thus assembled
noise-tuning characteristics of the BOLD signal for image sets with
natural second-order statistics. We found that these noise-tuning
curves were non-monotonic in occipital visual areas, and based on this
finding we formulate some predictions about the activity of the
underlying neural ensembles. Future recordings of the electrical
activity in monkeys will allow us to experimentally refute or verify
these hypotheses, and thus promise to advance our understanding of the
relationship between BOLD levels and neural ensemble activity.