This project aims to improve the use of near-infrared light for studying infants' brain activity. Although current optical methods of monitoring brain activity in infants show promise, many poorly-corrected variables (physical, physiological, and anatomical) still corrupt the data from too many infant participants. Through the research team's combination of expertise in biophotonics, brain and cognitive sciences, and pediatrics, the sources of noise will be reduced to levels where meaningful scans can be performed on babies routinely. The method used will be near-infrared spectroscopy (NIRS), which measures changes in the absorption of light by blood in the scalp and brain. The instrumentation will include dedicated "scalp-only" channels whose source-detector separations (~5 mm) are too short to be sensitive to brain signals. When one of these channels' readout is subtracted from standard channels (with separations of 20-35 mm), much physiological noise is cancelled, and stimulus related activations become easier to observe. The researchers' home-built corrected-near infrared-spectroscopy (C-NIRS) system for adults will be restructured for infant studies and enhanced with more sources and detectors, enabling measurements from a stimulated region and concurrent monitoring of a "control" region. An instrument of this scale designed with dedicated near-channel noise-suppression will be the first of its kind. In parallel, a more flexible silicone-based headband will be developed to fit a range of head shapes, be comfortable and safe for infants, and reduce the amplitude of motion artifacts in the data. The new instrument will be tested on a cohort of 60 healthy, alert infant participants (age 6-9 mos.), along with a commercial near-infrared instrument that lacks correction channels. Measurement protocols will focus on well-studied visual and auditory stimulation paradigms. The reductions in physiological noise and motion artifacts should yield a higher "hit rate" of meaningful data runs using the C-NIRS instrument than for traditional NIRS, thereby establishing C-NIRS as a valuable tool in the arsenal of the cognitive scientist studying infant development.
