Pierre LeVan1, Thimo Grotz1, Benjamin Zahneisen1, Maxim Zaitsev1, Juergen Hennig1
This study investigates the effect of respiratory and cardiac artifacts in the fMRI signal using very high-temporal resolution acquisitions (TR=80ms). It is shown that high-order harmonics of the respiratory (up to order 5) and cardiac (up to order 10) signals account for widespread, statistically significant effects in the fMRI signal (p<0.05). Moreover, the amplitude of the cardiac artifact is shown to be significantly modulated by the respiratory signal. This effect was seen in 81% of the studied brain volume in 7 healthy subjects. The proper modeling of these artifacts could increase the sensitivity of fMRI studies.