Infants can use their expectations about the world to rapidly shape their developing brains, researchers have found.
A series of experiments with infants ages 5 to 7 months has shown that portions of babies’ brains responsible for visual processing respond not just to the presence of visual stimuli, but also to the mere expectation of visual stimuli, according to the researchers from Princeton University, the University of Rochester and the University of South Carolina.
That type of sophisticated neural processing was once thought to happen only in adults and not infants, whose brains are still developing important neural connections.
“We show that in situations of learning and situations of expectations, babies are in fact able to really quickly use their experience to shift the ways different areas of their brain respond to the environment,” said Lauren Emberson, one of the researchers, who will join the Princeton faculty Sept. 1 as an assistant professor of psychology. She comes to Princeton from the University of Rochester, where she is a postdoctoral associate.
The research is described in the article, “Top-down modulation in the infant brain: Learning-induced expectations rapidly affect the sensory cortex at 6 months,” published online June 20 in the Proceedings of the National Academy of Sciences. The other authors are John Richards of the University of South Carolina and Richard Aslin of the University of Rochester.
The researchers exposed one group of infants to a pattern that included a sound — like a honk from a clown horn or a rattle — followed by an image of a red cartoon smiley face. Another group saw and heard the same things, but without any pattern.
The researchers used functional near-infrared spectroscopy, a technology that measures oxygenation in regions of the brain using light, to assess brain activity as the infants were exposed to the sounds and images.
After exposing the infants to the sounds and images for a little over a minute, the researchers began omitting the image. For the infants who had been exposed to the pattern, brain activity was detected in the visual areas of the brain even when the image didn’t appear as expected.
“We find that the visual areas of the infant brain respond both when they see things, which we knew, but also when they expect to see things but don’t,” Emberson said.
The finding could help shed light on the mysteries of neural development, the researchers said.
“Part of the reason I wanted to establish this type of phenomenon in infants is because I think it’s a really good candidate mechanism for how infants are using their experiences to develop their brains,” Emberson said. “There’s a lot of work that shows babies do use their experiences to develop. That’s sort of intuitive, especially if you’re a parent, but we have no idea how the brain is actually using the experiences.”
The findings offer insights that can shape future research in the area, said Janet Werker, a professor and Canada research chair in the Department of Psychology at the University of British Columbia who studies the roots of language acquisition.
“Most exciting to me is the evidence this work provides that from very early in infancy, the cortex is able to set up expectations about incoming events,” said Werker, who was not involved in the research. “This shows that infants not only learn about their external worlds, but are ready — from very early in life — to make predictions about the co-occurrence of events on the basis of very brief previous experience. This work thus has the potential to transform future research on infant learning to focus not on just what infants can learn, but to look at learning as a more active process, focusing more on how learning begets subsequent learning.”
Emberson is continuing to explore the topic by examining the phenomenon in infants who are at risk for poor developmental outcomes, specifically those who were born prematurely. She also is examining whether infants’ visual expectations boost their visual abilities.
Funding: The research was primarily funded by the National Institutes of Child Health and Development.
Source: Michael Hotchkiss – Princeton
Image Credit: The image is credited to NeuroscienceNews.com.
Original Research: Full open access research for “Top-down modulation in the infant brain: Learning-induced expectations rapidly affect the sensory cortex at 6 months” by Lauren L. Emberson, John E. Richards, and Richard N. Aslin in PNAS. Published only July 20 2015 doi:10.1073/pnas.1510343112
Top-down modulation in the infant brain: Learning-induced expectations rapidly affect the sensory cortex at 6 months
Recent theoretical work emphasizes the role of expectation in neural processing, shifting the focus from feed-forward cortical hierarchies to models that include extensive feedback (e.g., predictive coding). Empirical support for expectation-related feedback is compelling but restricted to adult humans and nonhuman animals. Given the considerable differences in neural organization, connectivity, and efficiency between infant and adult brains, it is a crucial yet open question whether expectation-related feedback is an inherent property of the cortex (i.e., operational early in development) or whether expectation-related feedback develops with extensive experience and neural maturation. To determine whether infants’ expectations about future sensory input modulate their sensory cortices without the confounds of stimulus novelty or repetition suppression, we used a cross-modal (audiovisual) omission paradigm and used functional near-infrared spectroscopy (fNIRS) to record hemodynamic responses in the infant cortex. We show that the occipital cortex of 6-month-old infants exhibits the signature of expectation-based feedback. Crucially, we found that this region does not respond to auditory stimuli if they are not predictive of a visual event. Overall, these findings suggest that the young infant’s brain is already capable of some rudimentary form of expectation-based feedback.
“Top-down modulation in the infant brain: Learning-induced expectations rapidly affect the sensory cortex at 6 months” by Lauren L. Emberson, John E. Richards, and Richard N. Aslin in PNAS. Published only July 20 2015 doi:10.1073/pnas.1510343112