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Evaluation of Cognitive Function Using Time-Domain Optical Neuroimaging

Wednesday, June 14, 2023

11:00 AM-1:00 PM

BIOMED Master's Thesis Defense

Evaluation of Cognitive Function Using Time-Domain Optical Neuroimaging

Zack Goldblum, Master's Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Hasan Ayaz, PhD
Associate Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical neuroimaging technique that measures changes in the concentration of oxygenated hemoglobin in the outer cortex of the brain. By detecting these changes, fNIRS provides an indirect measure of neural activity. Recent advancements in system-on-a-chip optics have miniaturized ultrafast optical detectors, enabling time-domain (TD)-fNIRS measurements which capture the time-of-flight distribution of photons. The first wearable TD-fNIRS systems are now becoming available. One such system, featuring a high-density sensor array in a headset form factor, is Kernel Flow (Kernel Inc., Los Angeles, CA). The overall aim of this project was to validate the capabilities of this system through an investigation into the neural correlates of cognitive function.

A study was designed around eight cognitive tasks that elicit well-characterized responses across various brain regions. These tasks probe several domains of cognition including problem solving, working memory, attention, response inhibition, language function, and resting state. Healthy participants (n=15) volunteered for this study and completed these tasks while their brain activity and physiological responses were measured with the Kernel Flow system and a smart watch.

The results generally agree with previous investigations of these cognitive tasks and domains of cognition. Significant increases in neural activity were primarily found in the prefrontal cortex when participants were performing problem solving, working memory, and response inhibition functions. The right inferior frontal gyrus in particular, well known for its role in attentional control, was active across tasks that required focused attention. Responses were also elicited in temporal cortices and occipital visual association areas in several tasks. The cases where results from this study did not agree with prior evidence offer new directions for further investigations and potentially highlight the increased information content that the Kernel Flow system provides. As the first cognitive study to use this system, it sets a foundation for the use of this technology in explorations of human cognition.

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