The capacity to represent the world in terms of numerically distinct objects (i.e., object individuation) is a milestone in early cognitive development and forms the foundation for more complex thought and behavior. Over the past 10 to 15 yr, infant researchers have expended a great deal of effort to identify the origins and development of this capacity. In contrast, relatively little is known about the neural mechanisms that underlie the ability to individuate objects, in large part because there are a limited number of noninvasive techniques available to measure brain functioning in human infants. Recent research suggests that near-IR spectroscopy (NIRS), an optical imaging technique that uses relative changes in total hemoglobin concentration and oxygenation as an indicator of neural activation, may be a viable procedure for assessing the relation between object processing and brain function in human infants. We examine the extent to which increased neural activation, as measured by NIRS, could be observed in two neural areas known to be involved in object processing, the primary visual cortex and the inferior temporal cortex, during an object processing task. Infants aged 6.5 months are presented with a visual event in which two featurally distinct objects emerge successively to opposite sides of an occluder and neuroimaging data are collected. As predicted, increased neural activation is observed in both the primary visual and inferior cortex during the visual event, suggesting that these neural areas support object processing in the young infant. The outcome has important implications for research in cognitive development, developmental neuroscience, and optical imaging.

Sensitivity to spoken language is an integral part of infants' formative development, yet relatively little is known about the neural mechanisms that underlie the emerging ability to perceive and process speech. This is in large part because there are a limited number of non-invasive techniques available to measure brain functioning in human infants. Near-infrared spectroscopy (NIRS), an optical imaging technique that estimates changes in neuronal activity by measuring changes in total hemoglobin concentration and oxygenation, may be a viable procedure for assessing the relation between speech processing and brain function in human infants. While auditory processing data have been gathered from newborn and preterm infants using NIRS, such data have not been collected from older infants. Many behavioral measures used to establish linguistic sensitivity in this population are accompanied by visual stimuli; however, it is unclear how coupling of auditory and visual stimuli influences neural processing. Here we studied cortical activity in infants aged 6-9 months, as measured by NIRS, during exposure to linguistic stimuli paired with visual stimuli and compared this to the activity observed in the same regions during exposure to visual stimuli alone. Results dissociate infants' hemodynamic responses to multimodal and unimodal stimuli, demonstrating the utility of NIRS for studying perceptual development in infants. In particular, these findings support the utility of NIRS for studying the neurobiology of language development in older infants, a task that is difficult to accomplish without the use of attention-getting visual stimuli.Infants' ability to perceive speech begins in the womb, and progresses dramatically during the first year of life (DeCasper and Fifer, 1980;Werker and Tees, 1984). Research indicates that during the last trimester in-utero (Mehler et al., 1988), and in the first twelve months of life post-natally (Jusczyk, 1997), infants become aware of and adjust to regularities in their native language. By using various cues found in adult speech, infants gradually come to understand and use their native language. For example, between 6 and 9 months of age, infants become sensitive to patterns within their native language, such as prosodic cues (Cutler, 1990;Morgan, 1996), phonotactic cues (Hohne and Jusczyk, 1994;Jusczyk et al., 1994), and allophonic variation (Hohne and Jusczyk, 1994). Investigating and understanding the mechanisms of the trajectory of such advances is a difficult task, and researchers have advanced the study of infant speech perception largely based on clever behavioral paradigms (e.g., Eimas et al., 1971;Trehub, 1973;Jusczyk et al., 1993;Saffran et al., 1996).The behavioral methods used to understand language development across infants' first year are typically chosen based on the specific age group being studied and the particular question being asked. For example, with infants four months of age and younger, a useful method employs a pacifier to record changes in infant su...

Over the past 30 years researchers have learned a great deal about the development of object processing in infancy. In contrast, little is understood about the neural mechanisms that underlie this capacity, in large part because there are few techniques available to measure brain functioning in human infants. The present research examined the extent to which near-infrared spectroscopy (NIRS), an optical imaging technique, could be used to assess the relation between object processing and brain functioning. Infants aged 6.5 months were presented with an occlusion event involving objects that differed on many feature dimensions (multi-featural change), differed on shape only (shape change) or color only (color change), or did not differ (control). NIRS data were collected in the occipital and inferior temporal cortex. In the occipital cortex, a significant increase in oxyhemoglobin (HbO(2)) was observed in response to all four events and these responses did not differ significantly from each other. In the inferior temporal cortex, a significant increase in HbO(2 )was observed in the multi-featural and the shape change condition but not in the control condition. An increase was also observed in the color change condition but this increase did not differ significantly from baseline nor did it differ significantly from the response obtained in the control condition. These data were discussed in terms of (a) what they suggest about the neural basis of feature processing in infants and (b) the viability of using NIRS to study brain-behavior relations in infants.

Over the last 20 years neuroscientists have learned a great deal about the ventral and dorsal object processing pathways in the adult brain, yet little is known about the functional development of these pathways. The present research assessed the extent to which different patterns of neural activation, as measured by changes in blood volume and oxygenation, are observed in infant visual and temporal cortex in response to events that involve processing of featural differences or spatiotemporal discontinuities. Infants aged 6.5 months were tested. Increased neural activation was observed in visual cortex in response to a featural-difference and a spatiotemporal-discontinuity event. In addition, increased neural activation was observed in temporal cortex in response to the featuraldifference but not the spatiotemporal-discontinuity event. The outcome of this experiment reveals early functional specialization of temporal cortex and lays the foundation for future investigation of the maturation of object processing pathways in humans. Keywordsinfants; near-infrared spectroscopy; object processing; featural information; spatiotemporal information Over the last 20 years a great deal of research has been conducted on the neural basis of object processing. Early studies conducted with non-human primates suggested that there are two Address for correspondence: Teresa Wilcox, Department of Psychology, Texas A&M University, 4235 TAMU, College Station,; email: E-mail: tgw@psyc.tamu.edu). Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptNeuropsychologia. Author manuscript; available in PMC 2010 February 1. (Livingstone & Hubel, 1988; De Yoe & Van Essen, 1988;Goodale & Milner, 1992;Mishkin, Ungerleider, & Macko, 1983;Ungerleider & Mishkin, 1982). The ventral route originates from the parvocellular layers of the lateral geniculate nucleus (LGN) and projects from the primary visual cortex to the temporal cortex and mediates processing of visual features important for the recognition and identification of objects. The dorsal route originates from the magnocellular layers of the LGN and projects from the primary visual cortex to the parietal cortex and is important for the analysis of motion, depth, and location. More recent studies with non-human (Orban, Van Essen, & Vanduffel, 2004;Tanaka, 2000;Tootell, Tsao, & Vanduffel, 2003; Tsunoda, Yamane, Nishkzaki, & Tanifuji, 2001;Wang, Tanifuji, & Tanaka, 1998;Wang, Tanaka, Tanifuji, 1996) and human (Bly & Kosslyn, 1997;Grill-Spector, Kourtzi, & Kanwisher, 2001;Grill-Spector et al., 1998;Haxby et al.,...