Functional Optical Brain Imaging Using Near-Infrared During Cognitive Tasks

A symbiotic relation between the operator and the operational environment can be realized by an advanced computing platform designed to understand and adapt to the cognitive and the physiological state of the user, especially during sensitive and cognitively demanding operations. The success of such a complex system depends not only on the efficacy of the individual components, but also on the efficient and appropriate integration of its parts. Because near infrared technology allows the design of portable, safe, affordable, and negligibly intrusive monitoring systems, the functional near infrared (fNIR) monitoring of brain hemodynamics can be of value in this type of complex system, particularly in helping to understand the cognitive and emotional state of the user during mentally demanding operations. This article presents the deployment and statistical analysis of fNIR spectroscopy for the purpose of cognitive state assessment while the user performs a complex task. This article is based on data collected during the Augmented Cognition-Technical Integration Experiment session. The experimental protocol for this session used a complex task, resembling a video game, called the Warship Commander Task (WCT). The WCT was designed to approximate naval air warfare management. Task difficulty and task load were manipulated by changing the following: (a) the number of airplanes that had to be managed at a given time, (b) the number of unknown (vs. known) airplane identities, and (c) the presence or absence of an auditory memory task. The fNIR data analysis explored the following: (a) the relations among cognitive workload, the participant's performance, and changes in blood oxygenation levels of the dorsolateral prefrontal cortex; and (b) the effect of divided attention as manipulated by the secondary component of the WCT (the auditory task). The primary hypothesis was that blood oxygenation in the prefrontal cortex, as assessed by fNIR, would rise with increasing task load and would demonstrate a positive correlation with performance measures. The results indicated that the rate of change in blood oxygenation was significantly sensitive to task load changes and correlated fairly well with performance variables.