title: Top-down modulation in the infant brain: Learning-induced expectations rapidly affect the sensory cortex at 6 months.
abstract: 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.
authors.affiliation: Psychology Department, Princeton University, Princeton, NJ 08542; Brain and Cognitive Sciences Department, University of Rochester, Rochester, NY 14627; Rochester Center for Brain Imaging, University of Rochester, Rochester, NY 14627; lauren.emberson@princeton.edu aslin@cvs.rochester.edu.
authors.forename: Lauren L
authors.initials: LL
authors.lastname: Emberson
authors.affiliation: Department of Psychology, University of South Carolina, Columbia, SC 29208; Institute for Mind and Brain, University of South Carolina, Columbia, SC 29201.
authors.forename: John E
authors.initials: JE
authors.lastname: Richards
authors.affiliation: Psychology Department, Princeton University, Princeton, NJ 08542; Rochester Center for Brain Imaging, University of Rochester, Rochester, NY 14627; lauren.emberson@princeton.edu aslin@cvs.rochester.edu.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Aslin
mesh_terms: D000161:Acoustic Stimulation; D001921:Brain / Q000502:physiology*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007223:Infant; D007858:Learning; D008297:Male; D009778:Occipital Lobe / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010775:Photic Stimulation; D013003:Somatosensory Cortex / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D010100:Oxygen
keywords: associative learning; fNIRS; infant; multisensory; perceptual development