K. Suzanne Scherf

Facing changes and changing faces in adolescence: a new model for investigating adolescent-specific interactions between pubertal, brain and behavioral development.

Adolescence is a time of dramatic physical, cognitive, emotional, and social changes as well as a time for the development of many social-emotional problems. These characteristics raise compelling questions about accompanying neural changes that are unique to this period of development. Here, we propose that studying adolescent-specific changes in face processing and its underlying neural circuitry provides an ideal model for addressing these questions. We also use this model to formulate new hypotheses. Specifically, pubertal hormones are likely to increase motivation to master new peer-oriented developmental tasks, which will in turn, instigate the emergence of new social/affective components of face processing. We also predict that pubertal hormones have a fundamental impact on the re-organization of neural circuitry supporting face processing and propose, in particular, that, the functional connectivity, or temporal synchrony, between regions of the face-processing network will change with the emergence of these new components of face processing in adolescence. Finally, we show how this approach will help reveal why adolescence may be a period of vulnerability in brain development and suggest how it could lead to prevention and intervention strategies that facilitate more adaptive functional interactions between regions within the broader social information processing network.

Connecting developmental trajectories: Biases in face processing from infancy to adulthood

The nature of the developmental trajectory of face recognition abilities from infancy through adulthood is multifaceted and currently not well understood. We argue that the understanding of this trajectory can be greatly informed by taking a more functionalist approach in which the influence of age-appropriate developmental tasks and goals are considered. To build this argument, we provide a focused review of developmental change across several important biases within face processing (species, race, age, and gender biases) from infancy through adulthood. We show that no existing theoretical framework can simultaneously and parsimoniously explain these very different trajectories and relative degrees of plasticity. We offer several examples of infant- and adolescent-specific developmental tasks that we predict have an essential influence on the content and description of information that individuals need to extract from faces at these very different developmental stages. Finally, we suggest that this approach may provide a unique opportunity to study the role of early experience in (i.e., age of acquisition effects) and the quality and range of experiences that are critical for shaping behaviors through the course of development, from infancy to adulthood.

Atypical development of face and greeble recognition in autism

BACKGROUND Impaired face processing is a widely documented deficit in autism. Although the origin of this deficit is unclear, several groups have suggested that a lack of perceptual expertise is contributory. We investigated whether individuals with autism develop expertise in visuoperceptual processing of faces and whether any deficiency in such processing is specific to faces, or extends to other objects, too. METHOD Participants performed perceptual discrimination tasks, including a face inversion task and a classification-level task, which requires especially fine-grained discriminations, on three classes of stimuli: socially-laden faces, perceptually homogenous novel objects, greebles, and perceptually heterogeneous common objects. RESULTS We found that children with autism develop typical levels of expertise for recognition of common objects. However, they evince poorer recognition for perceptually homogenous objects, including faces and, most especially, greebles. CONCLUSIONS Documenting the atypical recognition abilities for greebles in children with autism has provided an important insight into the potential origin of the relatively poor face recognition skills. Our findings suggest that, throughout development, individuals with autism have a generalized deficit in visuoperceptual processing that may interfere with their ability to undertake configural processing, and that this, in turn, adversely impacts their recognition of within-class perceptually homogenous objects.

Designing Serious Game Interventions for Individuals with Autism

The design of “Serious games” that use game components (e.g., storyline, long-term goals, rewards) to create engaging learning experiences has increased in recent years. We examine of the core principles of serious game design and examine the current use of these principles in computer-based interventions for individuals with autism. Participants who undergo these computer-based interventions often show little evidence of the ability to generalize such learning to novel, everyday social communicative interactions. This lack of generalized learning may result, in part, from the limited use of fundamental elements of serious game design that are known to maximize learning. We suggest that future computer-based interventions should consider the full range of serious game design principles that promote generalization of learning.

A Two-Hit Model of Autism: Adolescence as the Second Hit

Adolescence brings dramatic changes in behavior and neural organization. Unfortunately, for some 30% of individuals with autism, there is marked decline in adaptive functioning during adolescence. We propose a two-hit model of autism. First, early perturbations in neural development function as a “first hit” that sets up a neural system that is “built to fail” in the face of a second hit. Second, the confluence of pubertal hormones, neural reorganization, and increasing social demands during adolescence provides the “second hit” that interferes with the ability to transition into adult social roles and levels of adaptive functioning. In support of this model, we review evidence about adolescent-specific neural and behavioral development in autism. We conclude with predictions and recommendations for empirical investigation about several domains in which developmental trajectories for individuals with autism may be uniquely deterred in adolescence.

Two faces, two languages: an fMRI study of bilingual picture naming.

This fMRI study explores how nonlinguistic cues modulate lexical activation in the bilingual brain. We examined the influence of face race on bilingual language production in a picture-naming paradigm. Chinese-English bilinguals were presented with pictures of objects and images of faces (Asian or Caucasian). Participants named the picture in their first or second language (Chinese or English) in separate blocks. Face race and naming language were either congruent (e.g., naming in Chinese when seeing an Asian face) or incongruent (e.g., naming in English when seeing an Asian face). Our results revealed that face cues facilitate naming when the socio-cultural identity of the face is congruent with the naming language. The congruence effects are reflected as effective integration of lexical and facial cues in key brain regions including IFG, MFG, ACC, and caudate. Implications of the findings in light of theories of language processing and cultural priming are discussed.

Emerging Structure–Function Relations in the Developing Face Processing System

To evaluate emerging structure-function relations in a neural circuit that mediates complex behavior, we investigated age-related differences among cortical regions that support face recognition behavior and the fiber tracts through which they transmit and receive signals using functional neuroimaging and diffusion tensor imaging. In a large sample of human participants (aged 6-23 years), we derived the microstructural and volumetric properties of the inferior longitudinal fasciculus (ILF), the inferior fronto-occipital fasciculus, and control tracts, using independently defined anatomical markers. We also determined the functional characteristics of core face- and place-selective regions that are distributed along the trajectory of the pathways of interest. We observed disproportionately large age-related differences in the volume, fractional anisotropy, and mean and radial, but not axial, diffusivities of the ILF. Critically, these differences in the structural properties of the ILF were tightly and specifically linked with an age-related increase in the size of a key face-selective functional region, the fusiform face area. This dynamic association between emerging structural and functional architecture in the developing brain may provide important clues about the mechanisms by which neural circuits become organized and optimized in the human cortex.

Development of object recognition in humans

Although the ability to perceive simple shapes emerges in infancy, the ability to recognize individual objects as well as adults do continues to develop through childhood into adolescence. Despite this slow development, recent neuroimaging studies have revealed that an area of the ventral visual cortex that responds selectively to the category of common objects is adult-like by 5-8 years of age. The challenge for future research will be to identify the specific visual skills involved in object recognition that continue to develop through childhood and adolescence, and the neural mechanisms underlying this protracted development.

Individual differences in symptom severity and behavior predict neural activation during face processing in adolescents with autism.

Despite the impressive literature describing atypical neural activation in visuoperceptual face processing regions in autism, almost nothing is known about whether these perturbations extend to more affective regions in the circuitry and whether they bear any relationship to symptom severity or atypical behavior. Using fMRI, we compared face-, object-, and house-related activation in adolescent males with high-functioning autism (HFA) and typically developing (TD) matched controls. HFA adolescents exhibited hypo-activation throughout the core visuoperceptual regions, particularly in the right hemisphere, as well as in some of the affective/motivational face-processing regions, including the posterior cingulate cortex and right anterior temporal lobe. Conclusions about the relative hyper- or hypo-activation of the amygdala depended on the nature of the contrast that was used to define the activation. Individual differences in symptom severity predicted the magnitude of face activation, particularly in the right fusiform gyrus. Also, among the HFA adolescents, face recognition performance predicted the magnitude of face activation in the right anterior temporal lobe, a region that supports face individuation in TD adults. Our findings reveal a systematic relation between the magnitude of neural dysfunction, severity of autism symptoms, and variation in face recognition behavior in adolescents with autism. In so doing, we uncover brain–behavior relations that underlie one of the most prominent social deficits in autism and help resolve discrepancies in the literature.

Animal, but not human, faces engage the distributed face network in adolescents with autism.

Multiple hypotheses have been offered to explain the impaired face-processing behavior and the accompanying underlying disruptions in neural circuitry among individuals with autism. We explored the specificity of atypical face-processing activation and potential alterations to fusiform gyrus (FG) morphology as potential underlying mechanisms. Adolescents with high functioning autism (HFA) and age-matched typically developing (TD) adolescents were scanned with sMRI and fMRI as they observed human and animal faces. In spite of exhibiting comparable face recognition behavior, the HFA adolescents evinced hypo-activation throughout the face-processing system in response to unfamiliar human, but not animal, faces. They also exhibited greater activation in affective regions of the face-processing network in response to animal, but not human, faces. Importantly, this atypical pattern of activation in response to human faces was not related to atypical structural properties of the FG. This atypical neural response to human faces in autism may stem from abnormalities in the ability to represent the reward value of social (i.e. conspecific) stimuli.