Fig. 1.

Linear canonical models predict that the fMRI response to oscillatory neural activity will decrease exponentially as the oscillation frequency increases. (A) Diagram of the visual stimulus. The luminance contrast of a flickering radial checkerboard was modulated at 0.2, 0.33, 0.5, or 0.75 Hz. (B) Time course of the HRFs used for simulations. (C) Example of the predicted fMRI response to sinusoidally oscillating neural activity. As the frequency increases, the predicted response reaches a stable plateau, and the oscillation amplitude around that plateau becomes small. (D) Predicted fMRI response across stimulation frequencies. The predicted response declines exponentially for all HRFs. (E) The predicted fMRI response on a log scale for a linear system and for a sample set of nonlinear parameters shows that nonlinear adaptation effects would be expected to reduce the fMRI response amplitude further at high stimulus frequencies.