Brain vital signs: Auditory to visual translation

Date created: 
Evoked potentials
Vital signs
Cognitive processing
Cognitive neuroscience

An objective measure is greatly needed to monitor the impacts of injury or disease on our brain health. In order to provide such a measure, the brain vital sign framework utilizes an established, non-invasive, and physiology-based technology, Electroencephalogram (EEG), along with a rapid auditory sequence used to elicit and assess specific markers of cognitive function (marked by event-related potentials (ERPs)). To date, applications for brain vital signs have included evaluation of cognitive function in healthy and patient populations. To expand the applications, this study aims to translate the established rapid auditory sequence to a visual based assessment. The objectives are to: 1) demonstrate the viability of visual brain vital signs assessment and 2) examine the differences between the two modalities. EEG data was collected in 30 healthy adults (33±14yrs) and analyzed at central electrodes. Similar to the interlaced auditory sequence, the visual sequence utilized an oddball paradigm (standard vs. deviant stimuli) to evoke a sensory (N100) and attention (P300) response, and a word pair paradigm (congruent vs. incongruent stimuli) to evoke a semantic language response (N400). Comparison of mean amplitudes between stimuli revealed the targeted ERPs were successfully evoked in the visual modality at a group-level as expected (N100: p < 0.001; P300: p < 0.0001; N400: p = 0.0105). Attention processing (P300) was found to be the most transferrable across modalities, with no group-level differences and correlated peak amplitudes (rho = 0.7, p =0.0001) across individuals. Auditory P300 latencies were shorter than visual (p < 0.0001) but normalization and correlation (r =0.5, p = 0.0033) implied a potential systematic difference across modalities. Reduced auditory N400 amplitudes compared to visual (p = 0.0061) paired with normalization and correlation across individuals (r = 0.6, p = 0.0012), also revealed potential systematic modality differences between reading and listening language comprehension. This study provides initial understanding of the relationship between the visual and auditory sequences, while importantly establishing a visual sequence within the brain vital signs framework as a potential translational tool to monitor brain health over the human lifespan in broader populations, such as those with hearing impairments, congenital or due to injury or aging.

Document type: 
This thesis may be printed or downloaded for non-commercial research and scholarly purposes. Copyright remains with the author.
Senior supervisor: 
Stephen Robinovitch
Ryan D'Arcy
Science: Department of Biomedical Physiology and Kinesiology
Thesis type: 
(Thesis) M.Sc.