Fast multimodal neuroimaging for tracking whole-brain dynamics

Seminar | July 3 | 1-2:30 p.m. | 125 Li Ka Shing Center

 Laura Lewis, Harvard MGH

 Neuroscience Institute, Helen Wills

Many aspects of cognition take place on a timescale of hundreds of milliseconds, and measuring neural activity in this frequency range is essential for neuroscience. However, current non-invasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. We show 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. By integrating fast fMRI with simultaneous EEG at ultra high field (7 Tesla), we can detect local thalamic correlates of spontaneously varying cortical dynamics. Our preliminary results also demonstrate that this approach can identify new cortical and thalamic dynamic patterns that appear at the transition between wakefulness and sleep states. Our results identify new aspects of neural activity that can be measured through fast fMRI methods, and use this approach to track whole-brain dynamics across arousal states.