Power spectrum of spontaneous cerebral homodynamic oscillation shows a distinct pattern in autism spectrum disorder

Abstract

Spontaneous hemodynamic fluctuations recorded by functional near-infrared spectroscopy (fNIRS) from bilateral temporal lobes were analyzed on 25 children with autism spectrum disorder (ASD) and 22 typically developing (TD) children. By frequency domain analysis, a new characteristic was uncovered that the power spectrum of low frequency cerebral hemodynamic oscillation showed a distinct pattern in ASD. More specifically, at the frequency of 0.0200 Hz, the power of oxygenated hemoglobin was larger for TD than ASD, whereas in the band of 0.0267-0.0333 Hz, the power of deoxygenated hemoglobin was larger for ASD than TD. Using these new features and those identified previously together as feature variables for the support vector machine (SVM) classifier, accurate classification between ASD and TD was achieved with a sensitivity of 90.2%, specificity of 95.1% and accuracy of 92.7%.

Fig. 1

Schematic representation of the brain and locations of measurement channels over the bilateral temporal lobes, with 12 channels on each hemisphere [21].

Fig. 2

Power spectrum of HbO₂ and Hb on the left and right temporal lobe, for TD (blue line) and ASD (red line), respectively. The error bars are standard error of mean calculated from each group.

Fig. 3

The average (a) and the distribution (b) of power of HbO₂ at 0.0200 Hz, Hb at 0.0267 and 0.0333 Hz, for TD and ASD group, all on the right hemisphere. The differences are significant with p = 0.0023, 0.0049 and 0.0125, respectively. The effect size for the differences in power is 0.9361, 0.8540 and 0.7573, respectively.