Marta Bianciardi1, Masaki Fukunaga1, Peter van Gelderen1, Silvina G. Horovitz1, Jacco A. de Zwart1, Karin Shmueli1, Jeff H. Duyn1
1Advanced MRI Section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, USA, Bethesda, MD, USA
To exploit the increased BOLD contrast available at 7T for fMRI studies, it is crucial to identify the various noise sources. We determined the contribution of noise to fMRI signal fluctuations in the visual cortex and in the gray matter at 7T during rest. The following noise sources were considered: scanner instability, motion and BOLD effects due to respiration and cardiac cycles, thermal noise, and other sources, tentatively attributed to spontaneous neuronal activity. Our findings demonstrate that at 7T with a resolution of 3mm3 spontaneous fMRI activity is still one of the major contributors to the total fMRI signal fluctuations.