title: NEUROFEEDBACK USING FUNCTIONAL SPECTROSCOPY.
abstract: Neurofeedback based on real-time measurement of the blood oxygenation level-dependent (BOLD) signal has potential for treatment of neurological disorders and behavioral enhancement. Commonly employed methods are based on functional magnetic resonance imaging (fMRI) sequences that sacrifice speed and accuracy for whole-brain coverage, which is unnecessary in most applications. We present multi-voxel functional spectroscopy (MVFS): a system for computing the BOLD signal from multiple volumes of interest (VOI) in real-time that improves speed and accuracy of neurofeedback. MVFS consists of a functional spectroscopy (FS) pulse sequence, a BOLD reconstruction component, a neural activation estimator, and a stimulus system. The FS pulse sequence is a single-voxel, magnetic resonance spectroscopy sequence without water suppression that has been extended to allow acquisition of a different VOI at each repetition and real-time subject head motion compensation. The BOLD reconstruction component determines the T2* decay rate, which is directly related to BOLD signal strength. The neural activation estimator discounts nuisance signals and scales the activation relative to the amount of ROI noise. Finally, the neurofeedback system presents neural activation-dependent stimuli to experimental subjects with an overall delay of less than 1s. Here we present the MVFS system, validation of certain components, examples of its usage in a practical application, and a direct comparison of FS and echo-planar imaging BOLD measurements. We conclude that in the context of realtime BOLD imaging, MVFS can provide superior accuracy and temporal resolution compared with standard fMRI methods.
authors.affiliation: Athinoula A. Martinos Imaging Center at the McGovern Institute for Brain Research, Massachusetts Institute of Technology.
authors.forename: Oliver
authors.initials: O
authors.lastname: Hinds
authors.affiliation: Athinoula A. Martinos Imaging Center, Department of Radiology, Massachusetts General Hospital ; Harvard Medical School.
authors.forename: Paul
authors.initials: P
authors.lastname: Wighton
authors.affiliation: Athinoula A. Martinos Imaging Center, Department of Radiology, Massachusetts General Hospital ; Harvard Medical School.
authors.forename: M Dylan
authors.initials: MD
authors.lastname: Tisdall
authors.affiliation: Department of Human Biology, MRC/UCT Medical Imaging Research Unit, University of Cape Town, South Africa.
authors.forename: Aaron
authors.initials: A
authors.lastname: Hess
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital ; Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine.
authors.forename: Hans
authors.initials: H
authors.lastname: Breiter
authors.affiliation: Athinoula A. Martinos Imaging Center, Department of Radiology, Massachusetts General Hospital ; Harvard Medical School.
authors.forename: André
authors.initials: A
authors.lastname: van der Kouwe
keywords: Biofeedback; Spectroscopy; fMRI