Many aspects of high-level cognition take place on a timescale of hundreds of milliseconds, and measuring neural activity in this frequency range is important for cognitive neuroscience. However, current non-invasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. While fMRI has excellent spatial resolution, it has typically been limited to measuring slow timescale activity, as the hemodynamic response is generally thought to be sluggish. We used oscillating visual stimuli to drive a neural oscillation with known frequency, in order to test the temporal resolution of fMRI. We found that fast fMRI acquisition enables the direct detection of neural oscillations with frequencies of up to at least 0.75 Hz within single scan sessions. The amplitude of these oscillatory responses is an order of magnitude larger than predicted by canonical linear models, suggesting that the hemodynamic response can be surprisingly fast during ongoing neural activity. Our results suggest that fMRI can be used to localize 0.1–0.75 Hz oscillations in the human brain, and identify new aspects of neurovascular dynamics to take into account when using fast fMRI methods.

UPCOMING COG LUNCH TALKS

• 11/8/16 - Richard Futrell, Gibson/Levy Labs
• 11/22/16 - Malinda McPherson, McDermott Lab
• 11/29/16 - Lindsey Powell, Saxe Lab