White Matter Microstructure and Atypical Visual Orienting in 7-Month-Olds at Risk for Autism

“Clinical diagnosis was corroborated in the proband of high-risk infants with the Autism Diagnostic Interview–Revised (18).”

“selective attention has been comprehensively delineated in adults (6-10) and selective attention’s role in”

“selective attention has been comprehensively delineated in adults (6-10) and selective attention’s role in”

“A total of 97 infants completed the experimental task and were categorized into three groups based on risk status and ASD classification on the ADOS: low-risk infants (N=41), high-risk infants who did not meet ASD criteria on the ADOS (high-risk-negative group, N=40), and high-risk infants who met ADOS criteria for an…”

“First, linear affine registration of baseline images was applied to the structurally weighted T2 atlas using B-spline registration and normalized mutual information (24).”

“This tract may function in part as transitional connectivity between extrastriate visual areas and the dorsal frontoparietal and ventral frontoparietal orienting networks identified in adults (10).”

“We initially chose to focus on radial diffusivity because there have been reports linking this metric to myelination (30), and the relative myelin content is thought to support rapid and efficient signal transmission (31) and therefore efficient information processing.”

“Overlap latencies are consistently longer than gap latencies, likely resulting from 1) additional processing demands supported by the lateral intraparietal area (16, 21, 22) and 2) the absence of the fixation offset priming effects.”

“Although the neural circuitry of selective attention has been comprehensively delineated in adults (6– 10) and selective attention’s role in social cognition continues to be elucidated (10, 11), the precise circuitry that underlies selective visual attention during infancy is unknown.”

“The splenium is the most posterior sector of the corpus callosum and projects to striate and extrastriate visual areas and to portions of the posterior parietal cortex, including Brodmann’s area 7 (14), a cortical target implicated in sensorimotor programming (15).”

“selective attention has been comprehensively delineated in adults (6-10) and selective attention’s role in”

“Another study (2) reported that visual orienting latencies measured in a high-risk cohort at 12 months (N=27) correlated with autism symptom severity at 24 months.”

“Low-risk infants were excluded if they had a family history of a first- or seconddegree relative with autism or if the low-risk proband (older sibling) showed symptoms of ASD on the Social Communication Questionnaire (17).”

“Identifying infants at highest risk for ASD before the consolidation of syndromic features offers the possibility of implementing behavioral and other interventions during infancy that could reduce or prevent the manifestation of the full syndrome (40).”

“This study was primarily concerned with domain-general response patterns, as there is evidence to suggest that 6-month-old infants who later develop ASD exhibit patterns of “gaze to faces” and “gaze to objects” similar to those of 6-month-olds who do not develop ASD (4).”

“With regard to oculomotor efficiency, or performance in the gap condition, the difference between low-risk and high-risk-ASD infants was quite large and statistically significant, which suggests a marked deficit in the saccade-generating circuit (16, 22).”

“Developmental models of autism spectrum disorders (ASDs) suggest that atypical or biased visual attention patterns in the first year of life could directly contribute to the emergence of the characteristic social-cognitive deficits (1).”

“Second, a large deformation diffeomorphic metric mapping transformation was applied for unbiased, deformable atlas building (25).”

“The present behavioral findings not only complement and extend recent data suggesting early functional and structural brain abnormalities in infants who go on to develop ASD (41, 42), they also have the potential to enhance early identification of individuals with ASD and to inform targeted interventions developed for…”

“Results The sex ratio did not differ significantly across the three groups of children, and the groups did not differ statistically in age at the initial 6-month visit, age at the 24-month clinical visit, nonverbal developmental quotient as measured by the Mullen Scales of Early Learning at the 6-month visit, or stand…”

“We initially chose to focus on radial diffusivity because there have been reports linking this metric to myelination (30), and the relative myelin content is thought to support rapid and efficient signal transmission (31) and therefore efficient information processing.”

“Tensor maps were calculated from each data set using weighted least squares estimation (26) and were transformed into the atlas space with tensor reorientation by a finite strain approach (27).”

“Indeed, many of the early behavioral markers associated with later emerging ASD, specifically orienting to name, responding to bids for joint attention, spontaneous gaze to faces, and making eye contact (2-4), implicate behaviors associated with flexibly allocating attentional resources to salient or biologically rele…”

“The internal capsule and the corticospinal tracts myelinate earlier than cortical and commissural tracts (34), and the splenium undergoes more postnatal axonal elimination than any other sector of the corpus callosum (35), a process that likely extends into the sixth or seventh postnatal month in human infants.”

“Characterizing the neural correlates of visual attention during infancy may inform our understanding of cortical specialization, as experience with specific categories of information may sculpt neural circuits and enhance processing efficiency (12).”

“Future research using targeted imaging pulse sequences (34) has the potential to elucidate specific neuroanatomical mechanisms that underlie information processing during infancy.”

“Diffusion tensor images were transformed and averaged using the Riemannian and log-Euclidean frameworks (28), resulting in the final three-dimensional average tensor atlas.”

“With regard to oculomotor efficiency, or performance in the gap condition, the difference between low-risk and high-risk-ASD infants was quite large and statistically significant, which suggests a marked deficit in the saccade-generating circuit (16, 22).”

“In one study (13), 9- to 10month-old infants at high familial risk for developing autism (N=16) were reported to have longer visual orienting latencies compared with typically developing low-risk infants.”

“However, there is evidence to suggest that the density and diameter of axons in a given fiber tract, in addition to myelin content, affect the diffusion of water molecules perpendicular to the primary eigenvector of a fiber tract (32).”

“Image registration proceeded in two steps (23).”

“Previous research has shown that visual orienting latencies are related to encoding speed in 4-month-olds (37), which subsequently predicts cognitive outcomes in preschool-age children (38).”

“Tensor maps were calculated from each data set using weighted least squares estimation (26) and were transformed into the atlas space with tensor reorientation by a finite strain approach (27).”

“Previous research has shown that visual orienting latencies are related to encoding speed in 4-month-olds (37), which subsequently predicts cognitive outcomes in preschool-age children (38).”

“This pattern is consistent with studies examining DTI-related associations with attentional operations in adults (9), as well as behavioral evidence from a rare infant hemispherectomy patient (33).”

“This pattern is consistent with studies examining DTI-related associations with attentional operations in adults (9), as well as behavioral evidence from a rare infant hemispherectomy patient (33).”

“The splenium is the most posterior sector of the corpus callosum and projects to striate and extrastriate visual areas and to portions of the posterior parietal cortex, including Brodmann’s area 7 (14), a cortical target implicated in sensorimotor programming (15).”

“074), this pattern of results suggests that abnormal oculomotor functioning may be a familial marker of ASD (39).”

“It has long been recognized that selective attention shapes the development of adaptive cognitive function (5).”

“…to processing sensory information (e.g., left middle occipital cortex), consistent with regions previously reported to show the earliest increase in SA growth rate in typically developing infants 12 , and with reports showing early sensory differences in infants who will later develop ASD 13,14 .”

“Recently launched longitudinal imaging studies, as well as work examining white matter integrity in specific brain structures, may help to clarify neuroanatomic features influencing behaviors in ASD (56).”

“Atypical attention happens to be among the earliest signs of ASD, described in terms of the flexible and appropriate assignment of salience to stimuli (Elison et al., 2013; Zwaigenbaum et al., 2005).”

“Visual orienting latencies to nonsocial stimuli are atypically slow in 7 month olds who later meet ASD criteria (Elison et al., 2013).”