title: On multiple alternating steady states induced by periodic spin phase perturbation waveforms.
abstract: Direct measurement of neural currents by means of MRI can potentially open a high temporal resolution (10-100 ms) window applicable for monitoring dynamics of neuronal activity without loss of the high spatial resolution afforded by MRI. Previously, we have shown that the alternating balanced steady state imaging affords high sensitivity to weak periodic currents owing to its amplification of periodic spin phase perturbations. This technique, however, requires precise synchronization of such perturbations to the radiofrequency pulses. Herein, we extend alternating balanced steady state imaging to multiple balanced alternating steady states for estimation of neural current waveforms. Simulations and phantom experiments show that the off-resonance profile of the multiple alternating steady state signal carries information about the frequency content of driving waveforms. In addition, the method is less sensitive than alternating balanced steady state to precise waveform timing relative to radiofrequency pulses. Thus, multiple alternating steady state technique is potentially applicable to MR imaging of the waveforms of periodic neuronal activity.
authors.affiliation: Center for Functional MRI, Department of Radiology, University of California, San Diego, La Jolla, California 92037, USA. gburacas@ucsd.edu
authors.forename: Giedrius T
authors.initials: GT
authors.lastname: Buračas
authors.forename: Youngkyoo
authors.initials: Y
authors.lastname: Jung
authors.forename: Jongho
authors.initials: J
authors.lastname: Lee
authors.forename: Richard B
authors.initials: RB
authors.lastname: Buxton
authors.forename: Eric C
authors.initials: EC
authors.lastname: Wong
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Liu
mesh_terms: D000465:Algorithms; D001921:Brain / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels