Functional activation of the infant cortex during object processing

Abstract

A great deal is known about the functional organization of the neural structures that mediate visual object processing in the adult observer. These findings have contributed significantly to our conceptual models of object recognition and identification and provided unique insight into the nature of object representations extracted from visual input. In contrast, little is known about the neural basis of object processing in the infant. The current research used near-infrared spectroscopy (NIRS) as a neuroimaging tool to investigate functional activation of the infant cortex during an object processing task that has been used extensively with infants. The neuroimaging data revealed that the infant cortex is functionally specialized for object processing (i.e., individuation-by-feature) early in the first year but that patterns of activation also change between 3 and 12 months. These changes may reflect functional reorganization of the immature cortex or age-related differences in the cognitive processes engaged during the task.

Cortical activation to object shape and speed of motion during the first year

“…On the basis of these findings, one might expect younger infants, whose visual acuity is less well developed and hence depend more on motion-carried information to perceive object shape, to show greater activation in dorsal areas than older infants. Consistent with this hypothesis, Wilcox et al (2012) found that infants 3 to 5 months, but not infants aged 11 to 12 months, evidence activation in posterior parietal cortex during the different-shape event. Recall that from the early months of life infants individuate on the basis of shape (Wilcox, 1999) and both 3- to 5-month-olds and 11- to 12-month-olds show activation in anterior temporal cortex to the shape difference test event (Wilcox et al, 2012).…”

“…Consistent with this hypothesis, Wilcox et al (2012) found that infants 3 to 5 months, but not infants aged 11 to 12 months, evidence activation in posterior parietal cortex during the different-shape event. Recall that from the early months of life infants individuate on the basis of shape (Wilcox, 1999) and both 3- to 5-month-olds and 11- to 12-month-olds show activation in anterior temporal cortex to the shape difference test event (Wilcox et al, 2012). Yet, only the 3- to 5-month-olds show activation in posterior parietal cortex.…”

“…A growing number of studies (for a review see Lloyd-Fox, Blasi, & Elwell, 2010) have focused on identifying cortical substrates that mediate processing of distinct types of objects and/or object properties, many of which are theoretically important to cognitive and developmental neuroscientists. The outcome of such studies have allowed us to better understand how the human brain is functionally organized from the early days of life (Honda et al, 2010; Lloyd-Fox et al, 2009; Watanabe, Homae, Nakano, & Taga, 2008; Wilcox, Haslup, & Boas, 2010) and provide insight into how this might change with time and experience (Wilcox, Stubbs, Hirshkowitz, & Boas, 2012). Most relevant to the present research are studies that have focused on the cortical substrates that support infants’ emerging capacity to use featural and spatiotemporal information to track the identity of objects (Wilcox, Bortfeld, Armstrong, Woods, & Boas, 2009; Wilcox et al, 2012; Wilcox, Hirshkowitz, Hawkins, & Boas, 2014)…”

“…In one group of studies (Wilcox et al, 2012), infants 3 to 5 months (M age = 5, 8) and 11 to 12 months (M age = 11, 21) were shown occlusion events (Figure 1) in which the objects that emerged successively from behind the screen differed in shape (green ball-green box), color (green ball-red ball) or were identical in appearance (green ball-green ball). The cortical areas targeted were anterior temporal, posterior temporal, posterior parietal, and occipital cortex.…”

Imaging structural and functional brain development in early childhood

“…For example, task-based fMRI and FNIRS studies using passive stimuli have revealed adult-like positive blood-oxygen-level-dependent (BOLD) signals in response to sensorimotor 74, 75 , visual 76 , and auditory stimuli 77, 78 in human newborns and infants. FNIRS studies have documented the emergence and gradual improvement of various other functional responses during spatiotemporal processing 79 , object recognition 80 , learning 81 and social processing 82 , among other processes, during the first year of life. Nevertheless, non-invasive brain imaging of awake infants remains challenging owing to their motion and their inability to perform certain tasks, which limit such studies to a restricted set of brain functions.…”