Changes in Cytochrome-C-Oxidase Account for Changes in Attenuation of Near-Infrared Light in the Healthy Infant Brain

Abstract

A novel multi-wavelength broadband near infrared spectroscopy (NIRS) system has been employed to simultaneously measure haemodynamic changes alongside changes in cellular oxygen utilization by measurement of oxidation state of mitochondrial enzyme cytochrome-c-oxidase (oxCCO). The aim of this study was to investigate the role of oxCCO in neural responses to functional activation in infants. Studies were performed using a NIRS broadband system in 33 typically developing infants aged between 4 and 6 months. Responses were recorded over the right temporal lobe while infants were presented with engaging videos containing social and non-social content. Changes in the concentration of oxyhaemoglobin (Δ[HbO]), deoxyhaemoglobin (Δ[HHb]) and Δ[oxCCO] were calculated using changes in attenuation of light at 120 wavelengths between 780 and 900 nm using the UCLn algorithm. The algorithm was also used to fit (a) HbO and HHb spectra (2 component fit) and (b) HbO, HHb and oxCCO (3 component fit) to the change in attenuation occurring within an experimental block in different participants. Residuals resulting from these two fits were compared with oxidized-minus reduced CCO spectrum, calculated using the CCO specific extinction coefficient. A significant increase in oxCCO was found in response to the social stimuli (maximum increase 0.238 ± 0.13 μM). Residuals analysis showed that the best fits were achieved when oxCCO was included as a tissue chromophore. These results are the first reported significant change in oxCCO to stimulus-evoked activation in infants and may reveal vital information about oxygen metabolism during functional activation in the developing human brain.

Reference Ranges for Regional Cerebral Oxygen Saturation with Masimo O3 after Birth and Differences with Other Devices

“…The choice of the number of wavelengths should be based on the clinical application sought, because for detecting crSO 2 changes in hypoxia or hypercapnia conditions numerous wavelengths were not required. 37 In patients with conjugated hyperbilirubinemia, NIRS devices with more wavelengths provided higher crSO 2 values reducing bilirubin interference. 38,39 This study has several limitations.…”

“…However, increasing the number of wavelengths led to more complex algorithms, greater difficulty in signal processing and, in the end, more sophisticated and expensive devices. The choice of the number of wavelengths should be based on the clinical application sought, because for detecting crSO2 changes in hypoxia or hypercapnia conditions numerous wavelengths were not required 36 . In patients with conjugated hyperbilirubinemia, NIRS devices with more wavelengths provided higher crSO2 values reducing bilirubin interference 37,38 .…”

Attention and Capacity Limits in Perception: A Cellular Metabolism Account

“…In the present study, we used a multichannel BNIRS system, which has been developed to specifically measure oxCCO (e.g., Phan et al, 2016) and has been shown to successfully isolate its signal (based on the absorption characteristics of oxCCO, which has a broad peak at 830 nm) from other chromophores (HHb and HbO 2 ), as described here (Siddiqui et al, 2018). The instrument has 4 source and 10 detector fibers (optodes) and a sampling rate of 1 s. The detectors were arranged in rows of five with the four sources between them (source detector separation was 30 mm), resulting in 16 measurement channels.…”

Review of measurements and imaging of cytochrome-c-oxidase in humans using near-infrared spectroscopy: an update

“…This system has been used in a wide variety of research papers and was one of the first portable broadband systems capable of measuring oxCCO in a clinical setting, first described in 2014 [ 14 ]. miniCYRIL [ 36 ] is a miniature version of CYRIL, designed to be more portable so it can measure a wider variety of tasks in different settings. It comprises a miniature white light source, a customized miniature spectrometer, fiber-optic cables and a laptop for real-time visualization of results.…”