NIRS-EEG joint imaging during transcranial direct current stimulation: Online parameter estimation with an autoregressive model.
Transcranial direct current stimulation (tDCS) has been shown to perturb both cortical neural activity and hemodynamics during (online) and after the stimulation, however mechanisms of these tDCS-induced online and after-effects are not known. Here, online resting-state spontaneous brain activation may be relevant to monitor tDCS neuromodulatory effects that can be measured using electroencephalography (EEG) in conjunction with near-infrared spectroscopy (NIRS).



We present a Kalman Filter based online parameter estimation of an autoregressive (ARX) model to track the transient coupling relation between the changes in EEG power spectrum and NIRS signals during anodal tDCS (2mA, 10min) using a 4×1 ring high-definition montage.



Our online ARX parameter estimation technique using the cross-correlation between log (base-10) transformed EEG band-power (0.5-11.25Hz) and NIRS oxy-hemoglobin signal in the low frequency (≤0.1Hz) range was shown in 5 healthy subjects to be sensitive to detect transient EEG-NIRS coupling changes in resting-state spontaneous brain activation during anodal tDCS. Conventional sliding window cross-correlation calculations suffer a fundamental problem in computing the phase relationship as the signal in the window is considered time-invariant and the choice of the window length and step size are subjective. Here, Kalman Filter based method allowed online ARX parameter estimation using time-varying signals that could capture transients in the coupling relationship between EEG and NIRS signals.



Our new online ARX model based tracking method allows continuous assessment of the transient coupling between the electrophysiological (EEG) and the hemodynamic (NIRS) signals representing resting-state spontaneous brain activation during anodal tDCS.
Electronics and Communication Engineering, International Institute of Information Technology, Hyderabad, India.
Mehak
M
Sood
EUROMOV, Université de Montpellier, Montpellier, France.
Pierre
P
Besson
EUROMOV, Université de Montpellier, Montpellier, France.
Makii
M
Muthalib
Electronics and Communication Engineering, International Institute of Information Technology, Hyderabad, India.
Utkarsh
U
Jindal
EUROMOV, Université de Montpellier, Montpellier, France.
Stephane
S
Perrey
INRIA and Université de Montpellier, Montpellier, France. Electronic address: adutta@ieee.org.
Anirban
A
Dutta
INRIA and Université de Montpellier, Montpellier, France.
Mitsuhiro
M
Hayashibe
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000502:physiology; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D004569:Electroencephalography; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007874:Leghemoglobin / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009862:Online Systems; D019265:Spectroscopy, Near-Infrared; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
D007874:Leghemoglobin; C095131:oxyleghemoglobin
ARX model; Autoregulation; Cross-correlation; EEG; Hemodynamics; NIRS; Neurovascular coupling; tDCS