Forming reliable predictions about upcoming events are both essential to and the product of successful learning.Using fNIRS recording of cortical hemodynamics, we measured infants’ prediction of upcoming visual events that were pre-ceded by auditory cues in infants who are at-risk for poor development due to premature birth and their full-term peers. Wecompared prediction and learning across groups by fitting their occipital cortex response (which we assumed to reflect themagnitude of the prediction error) to a reinforcement learning model with a dynamic learning rate. We found that preemies hada lower learning rate than full-terms. These findings shed light on the origins of the developmental difficulties associated withprematurity.

We compared the influence of prior knowledge on visualperception in infants, children, and adults in order to explorethe developmental trajectory by which prior knowledge isintegrated with new sensory input. Using an identical taskacross age groups, we tested how participants’ accumulatedexperience affected their ability to judge the relative saturationlevels within a pair of sequentially-presented stimuli. We foundthat infants and children, relative to adults, showed greaterinfluence of the current observation and reduced influence ofmemory in their perception. In fact, infants and childrenoutperformed adults in discriminating between different levelsof saturation, and their performance was less biased bypreviously-experienced exemplars. Thus, the development ofperceptual integration of memory leads to less precisediscrimination in the moment, but allows observers to make useof their prior experience in interpreting a complex sensoryenvironment.

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit of novel methods to explore brain health and function. While the first report focused on neurophotonic tools mostly applicable to animal studies, here, we highlight optical spectroscopy and imaging methods relevant to noninvasive human brain studies. We outline current state-of-the-art technologies and software advances, explore the most recent impact of these technologies on neuroscience and clinical applications, identify the areas where innovation is needed, and provide an outlook for the future directions.