A spatial and temporal comparison of hemodynamic signals measured using optical and functional magnetic resonance imaging during activation in the human primary visual cortex

Abstract

Functional near infrared spectro-imaging (fNIRSI) is potentially a very useful technique for obtaining information about the underlying physiology of the blood oxygenation level dependent (BOLD) signal used in functional magnetic resonance imaging (fMRI). In this paper the temporal and spatial statistical characteristics of fNIRSI data are compared to those of simultaneously acquired fMRI data in the human visual cortex during a variable-frequency reversing checkerboard activation paradigm. Changes in the size of activated volume caused by changes in checkerboard reversal frequency allowed a comparison of the behavior of the spatial responses measured by the two imaging methods. fNIRSI and fMRI data were each analyzed using standard correlation and fixed-effect group analyses of variance pathways. The statistical significance of fNIRSI data was found to be much lower than that of the fMRI data, due mainly to the low signal-to-noise of the measurements. Reconstructed images also showed that, while the time-course of changes in the oxy-, deoxy-, and total hemoglobin concentrations all exhibit high correlation with that of the BOLD response, the changes in the volume of tissue measured as "activated" by the BOLD response demonstrate a closer similarity to the corresponding changes in the oxy-and total hemoglobin concentrations than to that of the deoxyhemoglobin.

Characterization of autism spectrum disorder with spontaneous hemodynamic activity

“…<0.1 Hz) resting-state fMRI signal correlates with the delta band spontaneous electric signal recorded from brain [30]. Given that HbO 2 and Hb are correlated with fMRI signal [31], the higher power of HbO 2 and Hb fluctuations recorded from ASD in the present work is in line with the MEG studies. In an effort to improve previous efforts at functional imaging diagnostic classification, we constructed a SVM model using salient components of our findings including bilateral correlation coefficients of HbO 2 , HbO 2 power and Hb power to differentiate between ASD and TD.…”

Stimulus and optode placement effects on functional near-infrared spectroscopy of visual cortex

“…Greatest levels of activation, and therefore increase in HbO, as a result of visual stimuli, have been observed from optodes that overlie the primary visual cortex [3][4][5] with a greater response typically seen in the left hemisphere. [6][7][8] The amount of activation measured tends to decrease with radial distance from this location. Using the International 10-20 System of Electrode Placement, 9 Wijeakumar et al 7 showed that the largest changes in hemoglobin concentration occurred at O1 and O2 as well as locations vertically between O1, O2, PO3, and PO4.…”

Detection of primary RGB colors projected on a screen using fNIRS

“…[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] It can provide both topographic 15,16,[34][35][36] and tomographic 14,37 brain images. Speci¯cally, fNIRS monitors regional cerebral blood°ow (rCBF) variations by measuring, at wavelengths between 700 nm and 1000 nm, the near-infrared-lightabsorption changes caused by concentration variations of HbO and HbR, the two primary absorbing chromophores in brain capillary blood.…”