Progressive and regressive developmental changes in neural substrates for face processing: testing specific predictions of the Interactive Specialization account

Face processing undergoes a fairly protracted developmental time course but the neural underpinnings are not well understood. Prior fMRI studies have only examined progressive changes (i.e., increases in specialization in certain regions with age), which would be predicted by both the Interactive Specialization (IS) and maturational theories of neural development. To differentiate between these accounts, the present study also examined regressive changes (i.e., decreases in specialization in certain regions with age), which is predicted by the IS but not maturational account. The fMRI results show that both progressive and regressive changes occur, consistent with IS. Progressive changes mostly occurred in occipital-fusiform and inferior frontal cortex whereas regressive changes largely emerged in parietal and lateral temporal cortices. Moreover, inconsistent with the maturational account, all of the regions involved in face viewing in adults were active in children, with some regions already specialized for face processing by 5 years of age and other regions activated in children but not specifically for faces. Thus, neurodevelopment of face processing involves dynamic interactions among brain regions including age-related increases and decreases in specialization and the involvement of different regions at different ages. These results are more consistent with IS than maturational models of neural development.     

Effects of structural similarity on neural substrates for object recognition

Human occipitotemporal cortex (OTC) is critically involved in object recognition, but the functional organization of this brain region is controversial. In the present study, functional magnetic resonance imaging (fMRI) signal changes were recorded in humans during an animal-matching task that parametrically varied degree of structural (i.e., shape) similarity among the items. fMRI signal in the midto anterior-fusiform gyrus increased as animals overlapped more in terms of structure and as reaction time increased. In contrast, relatively more posterior aspects of the fusiform gyrus and inferior occipital cortex showed greater fMRI signal when the animals overlapped less in terms of structure. A similar organization emerged when three-dimensional geometric shapes were matched, indicating that OTC is differentially tuned to varying degrees of overlap in object structure, regardless of taxonomic category. We discuss how the present findings fit in with current functional neuroanatomical approaches to object recognition.     

Neural developmental changes in processing inverted faces

We explored developmental changes in neural substrates for face processing, using fMRI. Children and adults performed a perceptual-matching task with upright and inverted face and animal stimuli. Behaviorally, inversion disrupted face processing more than animal processing for adults and older children. In line with this behavioral pattern, the left middle occipital gyrus showed a stronger face than animal inversion effect in adults. Moreover, a superior aspect of this region showed a greater face inversion effect in older than in younger children, indicating a developmental change in the processing of inverted faces. The visual regions recruited for inverted face processing in adults also overlapped more with brain regions involved in the viewing of upright objects than with regions involved in the viewing of upright faces in an independent localizer task. Hence, when faces are inverted, adults recruit regions normally engaged for recognizing objects, possibly pointing to a role for the featural processing of inverted faces.