Vigilance Task-Related Change in Brain Functional Connectivity as Revealed by Wavelet Phase Coherence Analysis of Near-Infrared Spectroscopy Signals

Abstract

This study aims to assess the vigilance task-related change in connectivity in healthy adults using wavelet phase coherence (WPCO) analysis of near-infrared spectroscopy signals (NIRS). NIRS is a non-invasive neuroimaging technique for assessing brain activity. Continuous recordings of the NIRS signals were obtained from the prefrontal cortex (PFC) and sensorimotor cortical areas of 20 young healthy adults (24.9 ± 3.3 years) during a 10-min resting state and a 20-min vigilance task state. The vigilance task was used to simulate driving mental load by judging three random numbers (i.e., whether odd numbers). The task was divided into two sessions: the first 10 min (Task t1) and the second 10 min (Task t2). The WPCO of six channel pairs were calculated in five frequency intervals: 0.6–2 Hz (I), 0.145–0.6 Hz (II), 0.052–0.145 Hz (III), 0.021–0.052 Hz (IV), and 0.0095–0.021 Hz (V). The significant WPCO formed global connectivity (GC) maps in intervals I and II and functional connectivity (FC) maps in intervals III to V. Results show that the GC levels in interval I and FC levels in interval III were significantly lower in the Task t2 than in the resting state (p < 0.05), particularly between the left PFC and bilateral sensorimotor regions. Also, the reaction time (RT) shows an increase in Task t2 compared with that in Task t1. However, no significant difference in WPCO was found between Task t1 and resting state. The results showed that the change in FC at the range of 0.6–2 Hz was not attributed to the vigilance task per se, but the interaction effect of vigilance task and time factors. The findings suggest that the decreased attention level might be partly attributed to the reduced GC levels between the left prefrontal region and sensorimotor area. The present results provide a new insight into the vigilance task-related brain activity.

Functional connectivity analysis of distracted drivers based on the wavelet phase coherence of functional near-infrared spectroscopy signals

“…Additional visual vigilance task reduced the coordinated regulation of cardiac activity and cerebral circulation between PFC and MC, and may affect substrate delivery and the removal of by-products of metabolism. Similar results were noted in previous research that focused on vigilance task-related changes on brain FC between PFC and sensorimotor areas [ 42 ]. The task might affect the functional hyperemia mechanism and further influence driving performance.…”

“…Subjects were asked by the experimenter to mentally solve two-digit addition and subtraction problems and relay the answer. The vigilance task was described in a previous study [ 42 ]. This task was applied in our experiment to simulate distraction from image or visual change.…”

Effects of Sleep Deprivation on Phase Synchronization as Assessed by Wavelet Phase Coherence Analysis of Prefrontal Tissue Oxyhemoglobin Signals

“…Different levels of task difficulty will lead to different levels of activity in the prefrontal lobe [8]. This is consistent with the experimental results in our previous study [49]. …”

Exploring brain functional connectivity in rest and sleep states: a fNIRS study

“…Similar to the results found using fMRI, the studies using fNIRS have revealed the networks of sensorimotor, visual, auditory, and language systems in the resting brain in the normal healthy subjects 15 – 19 . In addition to the resting-state, fNIRS has been used to investigate the brain functional connectivity during a vigilance task and in sleep deprivation subjects 20 , 21 . Furthermore, this technique was not only applied to the healthy participants, but Metzger et al .…”