Publications (2)2.3 Total impact
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Article: Real-time artifact filtering in continuous VEPs/fMRI recording.
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ABSTRACT: Continuous recording of Visual Evoked Potentials (VEPs) and functional Magnetic Resonance Imaging (fMRI) exploits the VEPs high temporal resolution and the fMRI high spatial resolution. In this work, we present a new method of continuous VEPs/fMRI recording to study visual function in seven normal subjects. Our real-time artifact filtering is characterized by a procedure based on an analytical study of echo-planar imaging (EPI) sequence parameters related electro-encephalogram (EEG)-artifact shapes. The magnetic field artifacts were minimized by using a dedicated amagnetic device and by a subtraction algorithm that takes into account the EPI sequence parameters. No significant decrease in signal-to-noise ratio was observed in case of EEG recording simultaneously with MR acquisition; similarly, transient and steady-state VEPs parameters were comparable during fMRI acquisition and in the off-phase of fMRI recording. We also applied this method to one patient with optic neuritis, and, compared with controls, found different results. We suggest that our technique can be reliably used to investigate the function of human visual cortex and properly correlate the electrophysiological and functional neuroimaging related changes.Journal of neuroscience methods 09/2009; 184(2):213-23. · 2.30 Impact Factor -
Article: Simultaneous recording of VEP and fMRI to study optic neuritis in multiple sclerosis
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ABSTRACT: Multiple sclerosis (MS) is a chronic, inflammatory disease that affects the central nervous system and causes gradual destruction of myelin. Inflammation of the optic nerve (optic neuritis, ON) is a common symptom at the onset of MS. Visual evoked potentials (VEPs) have been widely used as diagnostic tools for ON as they can detect the malfunctioning of visual pathways. Functional Magnetic Resonance Imaging (fMRI) has also been used to identify impaired visual brain function in ON patients. As VEPs and fMRI have complementary features (high temporal resolution and high spatial resolution, respectively), the integration of simultaneously recorded VEP and fMRI might provide more detailed information on the cortical representation of the visual stimulus, thus improving the diagnosis of ON. In this work, we present a method for simultaneous acquisition of EEG signals and fMRI. More specifically, we show that reliable VEPs can be obtained during fMRI acquisition and, conversely, sequences of MR images of good quality can be obtained in presence of EEG electrodes in the MRI bore. On the basis of these preliminary results, we suggest that the simultaneous recording of VEP and fMRI is feasible and can be used in studying ON.
