As infants look around them, objects routinely disappear and the later reappear. For example, a toy gets covered by a blanket, an electric train moves through a tunnel, or a cup is placed in the sink. One of infants' most challenging tasks is to keep track of these objects as they move in and out of view. How do infants' determine whether an object currently in view is the same object they saw before or a different object? What parts of the brain process this information? In the past, questions about the neural basis of object processing were difficult to answer because non-invasive techniques were not available to measure brain activity in awake, attending human infants. With support from the National Science Foundation, Dr. Teresa Wilcox will apply an optical imaging technique, near-infrared spectroscopy (NIRS), to the study of the infant brain. Near-infrared spectroscopy measures changes in cerebral blood flow from the scalp of the infant, and changes in blood flow are used an indicator of neural activation. This highly innovate approach will allow Dr. Wilcox and her colleagues to measure neural activation during object processing tasks. For example, these researchers will measure activation in the parietal cortex, an area that processes object motion in the adult, while infants watch an event in which an object changes its speed or path of motion. The broader impact of this funded project is that the successful application of NIRS, which is non-invasive, affordable, and relatively easy to use, will open the door for investigators to study the neural basis of other cognitive functions in infants, such as language or number processing. In addition, this project will enhance the neuroimaging resources and infrastructure at Texas A&M University and provide a unique educational resource for undergraduate and graduate students interested in neuroimaging of the human brain.
As infants look around them, objects routinely move in and out of view. For example, a ball rolls under the couch and reappears at another location or a toy is covered with a blanket and is later uncovered. One of infants’ most challenging tasks is to keep track of objects across space and time. How do infants’ determine whether an object currently in view is the same object they saw before or a different object? What parts of the brain process this information? In order to answer these questions, Dr. Teresa Wilcox applied near-infrared spectroscopy (NIRS) to study the infant brain. NIRS measures changes in cerebral blood flow from the scalp of the infant and changes in blood flow are used as an indicator of neural activation. There are two main types of information that infants could use to track the identity of an object, what it looks like (e.g., its shape) or how it moves through space (e.g., its path or speed of motion). This project investigated neural responses to these two types of information. Three main findings emerged. First, posterior parietal cortex was activated when objects changed their speed or path of motion in 3- to 7-month-olds (young infants) and 11- to 12-month-olds (old infants). Second, posterior parietal cortex was activated in the younger but not the older infants in response to shape differences. Third, posterior temporal cortex was activated in the younger but not older infants in response to all of the events. Fourth, regardless of whether infants saw a spatiotemporal discontinuity or a shape difference, anterior temporal cortex was activated when infants used that information to individuate the objects. Together, these results reveal: (1) that the posterior parietal cortex mediates processing of spatiotemporal information throughout the first year; (2) young infants are more likely than older infants to rely on motion-carried information, a parietal mediated function, to extract object shape; (3) paring down of cortical areas involved in object processing during the first year; and (4) a neural signature for object individuation that remains stable over time. The broader impacts of this project are that we have demonstrated that NIRS can identify functional changes in visual object processing areas in the healthy infant cortex during the first year. This is useful for researchers who seek a non-invasive imaging tool to identify deficits in visual object processing in young infants. These results also lay the foundation for more in-depth investigation of the functional development of the object processing areas in the human cortex. Finally, this project enhanced the neuroimaging resources and infrastructure at Texas A&M University and provided a unique educational resource for undergraduate and graduate students interested in studying early neural and behavioral development.
