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Simultaneous Data Collection of fMRI and fNIRS Measurements Using a Whole-Head Optode Array and Short-Distance Channels
Published on: October 20, 2023
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Stimulus and optode placement effects on functional near-infrared spectroscopy of visual cortex
Nasser H Kashou1, Brenna M Giacherio1
1Wright State University , Biomedical Imaging Laboratory, 3640 Colonel Glenn Highway, Dayton, Ohio 45435, United States.
Neurophotonics
|June 24, 2016
Summary
Functional near-infrared spectroscopy (fNIRS) shows potential for ophthalmology, but signal reliability needs improvement. This study found stimulus size impacts visual cortical signals, though session variability and hair characteristics affect results, hindering clinical use.
Area of Science:
- Neuroscience
- Ophthalmology
- Biomedical Engineering
Background:
- Functional near-infrared spectroscopy (fNIRS) offers non-invasive monitoring of brain activity.
- fNIRS has not yet been established as a standalone clinical tool in ophthalmology.
- Reliability of visual cortical signals measured by fNIRS requires further investigation.
Purpose of the Study:
- To assess the reliability of visual cortical signals using fNIRS.
- To investigate the impact of optode placement, stimulus size, and cap placement variability on fNIRS signal quality.
- To evaluate the influence of participant hair characteristics on fNIRS measurements.
Main Methods:
- Utilized the 10-20 International System with 28 channels for optode placement.
- Presented visual stimuli (checkerboards) at varying visual angles (1-18 degrees) and a frequency of 7.5 Hz.
- Collected data across three sessions per participant, analyzing channel response, stimulus size effects, and session variability.
Main Results:
- The 1-degree stimulus size elicited the greatest activation in visual cortical signals.
- Significant variability was observed, with one out of three data collection sessions yielding different results per participant.
- Hair color and thickness influenced overall oxygenated hemoglobin (HbO) levels, with hair color significantly affecting deoxygenated hemoglobin (HbD) levels.
Conclusions:
- fNIRS shows promise for assessing visual function but requires enhanced robustness and consistency for clinical implementation.
- Stimulus size is a critical factor in eliciting reliable visual cortical responses.
- Factors such as session variability and individual hair characteristics present challenges for standardized fNIRS application in ophthalmology.
