Detection and characterization of single-trial fMRI bold responses: paradigm free mapping.
This work presents a novel method of mapping the brain's response to single stimuli in space and time without prior knowledge of the paradigm timing: paradigm free mapping (PFM). This method is based on deconvolution of the hemodynamic response from the voxel time series assuming a linear response and using a ridge-regression algorithm. Statistical inference is performed by defining a spatio-temporal t-statistic and by controlling for multiple comparisons using the false discovery rate procedure. The methodology was validated on five subjects who performed self-paced and visually cued finger tapping at 7 Tesla, with moderate (TR = 2 s) and high (TR = 0.4 s) temporal resolution. The results demonstrate that detection of single-trial BOLD events is feasible without a priori information on the stimulus paradigm. The proposed method opens up the possibility of designing temporally unconstrained paradigms to study the cortical response to unpredictable mental events.
Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham.
César Caballero
CC
Gaudes
Natalia
N
Petridou
Ian L
IL
Dryden
Li
L
Bai
Susan T
ST
Francis
Penny A
PA
Gowland
D000328:Adult; D000465:Algorithms; D001921:Brain / Q000098:blood supply* / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D004576:Electromyography; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D011597:Psychomotor Performance; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult