Developing Brain Vital Signs: Initial Framework for Monitoring Brain Function Changes Over Time

Abstract

Clinical assessment of brain function relies heavily on indirect behavior-based tests. Unfortunately, behavior-based assessments are subjective and therefore susceptible to several confounding factors. Event-related brain potentials (ERPs), derived from electroencephalography (EEG), are often used to provide objective, physiological measures of brain function. Historically, ERPs have been characterized extensively within research settings, with limited but growing clinical applications. Over the past 20 years, we have developed clinical ERP applications for the evaluation of functional status following serious injury and/or disease. This work has identified an important gap: the need for a clinically accessible framework to evaluate ERP measures. Crucially, this enables baseline measures before brain dysfunction occurs, and might enable the routine collection of brain function metrics in the future much like blood pressure measures today. Here, we propose such a framework for extracting specific ERPs as potential “brain vital signs.” This framework enabled the translation/transformation of complex ERP data into accessible metrics of brain function for wider clinical utilization. To formalize the framework, three essential ERPs were selected as initial indicators: (1) the auditory N100 (Auditory sensation); (2) the auditory oddball P300 (Basic attention); and (3) the auditory speech processing N400 (Cognitive processing). First step validation was conducted on healthy younger and older adults (age range: 22–82 years). Results confirmed specific ERPs at the individual level (86.81–98.96%), verified predictable age-related differences (P300 latency delays in older adults, p < 0.05), and demonstrated successful linear transformation into the proposed brain vital sign (BVS) framework (basic attention latency sub-component of BVS framework reflects delays in older adults, p < 0.05). The findings represent an initial critical step in developing, extracting, and characterizing ERPs as vital signs, critical for subsequent evaluation of dysfunction in conditions like concussion and/or dementia.

Cognitive loading via mental arithmetic modulates effects of blink‐related oscillations on precuneus and ventral attention network regions

“…A recent study in our group also demonstrated these temporal and spectral characteristics using magnetoencephalography (MEG), further validating the existence of BRO effects across different modalities (Liu, Ghosh Hajra, Cheung, Song, & D'Arcy, 2017). Moreover, studies have also pointed to the potential utility of the BRO response in clinical brain function assessments (Bonfiglio et al, 2013(Bonfiglio et al, , 2014, with further possibility of deployment in bedside evaluations (Ghosh Hajra et al, 2016.…”

“…The BRO response has mainly been described under resting conditions with or without passive fixation, and is particularly prominent in the delta frequency range (0.5-4 Hz). Moreover, studies have also pointed to the potential utility of the BRO response in clinical brain function assessments (Bonfiglio et al, 2013(Bonfiglio et al, , 2014, with further possibility of deployment in bedside evaluations (Ghosh Hajra et al, 2016. A recent study in our group also demonstrated these temporal and spectral characteristics using magnetoencephalography (MEG), further validating the existence of BRO effects across different modalities (Liu, Ghosh Hajra, Cheung, Song, & D'Arcy, 2017).…”

Multimodal characterization of the semantic N400 response within a rapid evaluation brain vital sign framework

“…As introduced elsewhere [ 37 ], the rapid assessment framework utilizes a compressed auditory stimulus sequence with interlaced tones and words to elicit brain responses across four different functional domains—auditory sensation (N100 ERP), attention (P300 ERP), and semantic language (N400 ERP)—in approximately 5 min (Fig. 1 ).…”

“…We previously demonstrated the successful evaluation of the N400 response in 100 healthy individuals using a point-of-care enabled device [ 34 ], then employed this device to track the progress of rehabilitation therapy in a brain-injured patient [ 6 ]. More recently, we demonstrated a rapid evaluation platform known as the ‘brain vital sign’ framework [ 37 ], which enables the rapid assessment of several brain function indicators including the N400 (semantic language), N100 (sensory processing) [ 38 ] and P300 (attention orienting) [ 39 ]. The brain vital sign framework employs a portable, low-density EEG system, with automated, user-friendly software for easy clinical applications.…”

“…The testing paradigm utilizes a short, 5-min auditory stimulus sequence in which tone and word stimuli are interlaced to maximize the number of trials and signal-to-noise ratio. Results in healthy adults showed that, not only were the target responses successfully elicited at the individual level, but the platform also captured expected age-related changes in attention and cognition that were undetected using conventional clinical screening measures [ 37 ].…”