This study investigated the effects of familiarization and attention on event-related potential (ERP) correlates of recognition memory in infants. Infants 4.5, 6, or 7.5 months of age were either familiarized with 2 stimuli that were used during later testing or presented 2 stimuli that were not used later. Then, infants were presented with a recording of Sesame Street to elicit attention or inattention and presented with familiar and novel stimuli. A negative ERP component over the frontal and central electrodes (Nc) was larger in the preexposure familiarization group for novel-than for familiar-stimulus presentations, whereas the Nc did not differ for the group not receiving a familiarization exposure. Spatial independent components analysis of the electroencephelogram and "equivalent current dipole" analysis were used to examine putative cortical sources of the ERP components. The cortical source of Nc was located in areas of prefrontal cortex and anterior cingulate cortex.Visual attention and recognition memory in infants are closely related. For example, infants demonstrate greater memory for events they were exposed to while in an attentive state than for events they were exposed to in an inattentive state (Frick & Richards, 2001;Richards, 1997). Events that have been partially encoded into memory or events that are novel elicit larger attention responses than those events that have been fully encoded (Bornstein, 1985;Fantz, 1961Fantz, ,1963. Infants show larger orienting responses to novel events than to those events that are familiar to them. Studies examining visual attention and recognition memory simultaneously can provide insight into the overall cognitive activity involved in an organism's adaptive responses to environmental information. The present study shows that attentionelicited event-related potential (ERP) responses differ as a function of the infant's familiarity with the stimuli and suggests that these effects are mediated by the prefrontal cortex of the brain.Several studies of infant recognition memory development have used the electroencephelogram (EEG) to measure ERPs related to recognition memory. ERPs are scalp voltage oscillations that are time locked with a specific physical or mental event (Fabiani, Gratton, & Coles, 2000;Picton et al., 2000). Courchesne, Ganz, and Norcia (1981) recorded ERP during an oddball procedure. They exposed 10 infants from 4 to 7 months of age to tachistoscopically presented slides of two unfamiliar female faces. One female face was presented on 88% of the trials (standard stimulus), and the other female face was presented on 12% of the trials (oddball stimulus). A negative component over the frontal and central electrodes with a latency of 700 ms, labeled Nc ("negative central"), was larger to the oddball stimulus than to the standard stimulus. A later occurring (latency = 1,360 ms) positive component followed both the infrequently and frequently presented stimuli. The authors concluded that the frequently presented stimulus was more familiar to t...

To examine the developmental course of look duration as a function of age and stimulus type, 14-to 52-week-old infants were shown static and dynamic versions of faces, Sesame Street material and achromatic patterns for 20 seconds of accumulated looking. Heart rate was recorded during looking and parsed into stimulus orienting, sustained attention, and attention termination phases of attention. Infants' peak look durations indicated that prior to 26 weeks there was a linear decrease with age for all stimuli. Older infants' look durations continued to decline for patterns but increased for Sesame Street and faces. Measures of heart rate change during sustained attention and the proportion of time spent in each phase of attention confirmed infants' greater engagement with the more complex stimuli.Infants' Attention to Patterned Stimuli: Developmental Change from 3 to 12 Months of Age Measures of visual attention obtained from habituation and selective looking (e.g., pairedcomparison; novelty preference) procedures have provided a wealth of information about the development of infants' sensory, perceptual, and cognitive capabilities (for reviews see Haith & Benson, 1998;Kellman & Banks, 1998). More recently, these procedures have become important in their own right with growing evidence that components of infants' attention during habituation and selective looking also provide information about the functioning and early development of the human information-processing system (see Bornstein, 1998;Colombo, 1993;Fagan, 1990;Hayne, 2004;McCall, 1994;Rose, Feldman, & Jankowski, 2004). The underlying reasoning is not new and is based on the assumption that the process of habituation represents a ubiquitous and elementary form of learning during which the infant constructs an internal representation (trace, or engram) of an external stimulus. As the infant's attention to the stimulus progresses and its representation becomes complete, his or her attention to it wanes. The subsequent presentation of a novel stimulus elicits a recovery of attention (dishabituation, or a novelty preference) as the infant presumably compares its features to the internal representation of the familiar stimulus, "recognizes" at some level that it is unrepresented or weakly represented in memory, and begins the process of trace construction once more (Sokolov, 1963). These same familiarization, comparison, and recognition processes are also presumed to occur without complete habituation, as infants will show visual preference for a novel stimulus even after fairly brief exposure to a standard (see Fagan,

Several research groups have identified a network of regions of the adult cortex that are activated during social perception and cognition tasks. In this paper we focus on the development of components of this social brain network during early childhood and test aspects of a particular viewpoint on human functional brain development: “interactive specialization.” Specifically, we apply new data analysis techniques to a previously published data set of event-related potential ~ERP! studies involving 3-, 4-, and 12-month-old infants viewing faces of different orientation and direction of eye gaze. Using source separation and localization methods, several likely generators of scalp recorded ERP are identified, and we describe how they are modulated by stimulus characteristics. We then review the results of a series of experiments concerned with perceiving and acting on eye gaze, before reporting on a new experiment involving young children with autism. Finally, we discuss predictions based on the atypical emergence of the social brain network

This study examined the effect of attention in infants on the ERP changes occurring during the recognition of briefly presented visual stimuli. Infants at ages 4.5, 6 and 7.5 months were presented with a Sesame Street movie that elicited periods of attention and inattention, and computer-generated stimuli were presented overlaid on the movie for 500 ms. One stimulus was familiar to the infants and was presented frequently, a second stimulus was familiar but presented infrequently, and a set of 14 novel stimuli were presented infrequently. An ERP component labeled the 'Nc' (Negative Central, about 450-550 ms after stimulus onset) was larger during attention than inattention and increased in magnitude over the three testing ages during attention. Late slow waves in the ERP (from 1000 to 2000 ms post-stimulus onset) consisted of a positive slow wave in response to the infrequent familiar stimulus at all three testing ages. The late slow wave in response to the infrequent novel stimulus during attention was a positive slow wave for the 4.5-month-old infants, to a positivenegative slow wave for the 6-month-old infants and a negative slow wave for the 7.5-month-old infants. These results show attention facilitates the brain response during infant recognition memory and show that developmental changes in recognition memory are closely related to changes in attention.

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.O ver the past two decades, theoretical focus has shifted from predominantly feed-forward hierarchies of cortical function, where sensory cortex propagates information to higher level analyzers on the way to decision and motor control areas, to models in which feedback connections to lower-level cortical regions allow extensive top-down functional modulation based on expectation (1). An influential model for incorporating feedback is predictive coding, which compares expectations or predictions to input at each level of the processing hierarchy (2-4). There is extensive and compelling evidence for expectation-based modulation even at the earliest levels of sensory processing in both humans (5-7) and nonhuman animals (8). Because complex, naturalistic sensory input is characterized by temporal, spatial, and contextual regularities, the ability to modulate early sensory function as a result of expectations is believed to support adaptive perceptual abilities (4).Empirical evidence for expectation-based feedback, however, is restricted to adult humans and nonhuman animals. With their extensive experience, adults already have developed sophisticated internal models of the environment and have a highly interconnected brain and efficient neural processing. Comparatively, human infants are born with a demonstratively immature behavioral repertoire, have underdeveloped sensorimotor and cognitive capacities, and lack sophisticated internal models of the environment. These internal models undergo substantial postnatal development even in the early sensory cortex. For example, spontaneous activity of primary visual cortex (V1) in ferrets converges with e...

This article summarizes a life-span neurodevelopmental MRI database. The study of neurostructural development or neurofunctional development has been hampered by the lack of age-appropriate MRI reference volumes. This causes misspecification of segmented data, irregular registrations, and the absence of appropriate stereotaxic volumes. We have created the “Neurodevelopmental MRI Database” that provides age-specific reference data from 2 weeks through 89 years of age. The data are presented in fine-grained ages (e.g., 3 months intervals through 1 year; 6 months intervals through 19.5 years; 5 year intervals from 20 through 89 years). The base component of the database at each age is an age-specific average MRI template. The average MRI templates are accompanied by segmented partial volume estimates for segmenting priors, and a common stereotaxic atlas for infant, pediatric, and adult participants. The database is available online (http://jerlab.psych.sc.edu/NeurodevelopmentalMRIDatabase/).

Spatial normalization and segmentation of pediatric brain MRI data with adult templates may impose biases and limitations in pediatric neuroimaging work. To remedy this deficiency, we created a single database made up of a series of pediatric, age-specific MRI average brain templates. These average, age-specific templates were constructed from brain scans of individual children obtained from two sources: (1) the NIH MRI Study of Normal Brain Development and (2) MRIs from University of South Carolina’s McCausland Brain Imaging Center. Participants included young children enrolled at ages ranging from 8 days through 4.3 years of age. A total of 13 age group cohorts spanning the developmental progression from birth through 4.3 years of age were used to construct age-specific MRI brain templates (2 weeks, 3, 4.5, 6, 7.5, 9, 12, 15, 18 months, 2, 2.5, 3, 4 years). Widely-used processing programs (FSL, SPM, ANTS) extracted the brain and constructed average templates separately for 1.5T and 3T MRI volumes. The resulting age-specific, average templates showed clear changes in head and brain size across ages and between males and females, as well as changes in regional brain structural characteristics (e.g., myelin development). This average brain template database is available via our website (http://jerlab.psych.sc.edu/neurodevelopmentalmridatabase) for use by other researchers. Use of these age-specific, average pediatric brain templates by the research community will enhance our ability to gain a clearer understanding of the early postnatal development of the human brain in health and in disease.

This study examined the effect of attention on 3- to 6-month-olds responses to briefly exposed visual stimuli. In Study I, stimuli presented at 2.5 or 5.0 s resulted in a familiarity preference in a subsequent paired-comparison procedure. A novelty preference was found with 10.0- or 20.0-s exposure durations. In Study 2, a Sesame Street movie elicited heart-rate-defined attention phases and stimuli replaced Sesame Street during sustained attention, attention termination, or 5.0 s following attention termination. For 20 and 26-week-olds. Stimuli presented for 5.0 s during sustained attention resulted in a novelty preference similar to that found when exposure time was 20.0 s. The duration of stimulus exposure during sustained attention in the familiarization phase was positively correlated with the preference for the novel stimulus in the paired-comparison procedure. Thus, processing of briefly presented visual stimuli differs depending on the type of attention in which the infant is currently engaged.