Evgeniya Kirilina1, Alexnader Jelzow2, Ruediger Bruehl2, Angela Heine1, Michael Niessing1, Arthur M. Jacobs1, Bernd Ittermann2, Heidrun Wabnitz2, Rainer Macdonald2, Ilias Tachtsidis3
1Free University of Berlin, Berlin, Germany; 2Physikalisch-Technische Bundesanstalt, Berlin, Germany; 3Department Medical Physics & Bioengineering, University College London, London, United Kingdom
Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique for studying the functional organization of the human brain by measuring haemodynamic responses to stimuli in the cerebral cortex. A major challenge of fNIRS is its high sensitivity to haemodynamic fluctuations in the scalp. Here, we combined fNIRS, fMRI and peripheral physiological measurements in order to explore the physiological origin of superficial signals in fNIRS and develop a method to separate them from cortical signals. Using high resolution fMRI data, we show that the main origin of artifacts in fNIRS is task-evoked venous vasoconstriction in the scalp.