@article {205, title = {Age-related changes in tissue signal properties within cortical areas important for word understanding in 12- to 19-month-old infants.}, journal = {Cereb Cortex}, volume = {24}, year = {2014}, month = {2014 Jul}, pages = {1948-55}, abstract = {

Recently, our laboratory has shown that the neural mechanisms for encoding lexico-semantic information in adults operate functionally by 12-18 months of age within left frontotemporal cortices (Travis et al., 2011. Spatiotemporal neural dynamics of word understanding in 12- to 18-month-old-infants. Cereb Cortex. 8:1832-1839). However, there is minimal knowledge of the structural changes that occur within these and other cortical regions important for language development. To identify regional structural changes taking place during this important period in infant development, we examined age-related changes in tissue signal properties of gray matter (GM) and white matter (WM) intensity and contrast. T1-weighted surface-based measures were acquired from 12- to 19-month-old infants and analyzed using a general linear model. Significant age effects were observed for GM and WM intensity and contrast within bilateral inferior lateral and anterovental temporal regions, dorsomedial frontal, and superior parietal cortices. Region of interest (ROI) analyses revealed that GM and WM intensity and contrast significantly increased with age within the same left lateral temporal regions shown to generate lexico-semantic activity in infants and adults. These findings suggest that neurophysiological processes supporting linguistic and cognitive behaviors may develop before cellular and structural maturation is complete within associative cortices. These results have important implications for understanding the neurobiological mechanisms relating structural to functional brain development.

}, keywords = {Aging, Brain Mapping, Cerebral Cortex, Comprehension, Female, Humans, Image Processing, Computer-Assisted, Infant, Language Development, Magnetic Resonance Imaging, Male, Vocabulary}, issn = {1460-2199}, doi = {10.1093/cercor/bht052}, author = {Travis, Katherine E and Curran, Megan M and Torres, Christina and Leonard, Matthew K and Brown, Timothy T and Dale, Anders M and Elman, Jeffrey L and Halgren, Eric} } @article {181, title = {Atypical social referencing in infant siblings of children with autism spectrum disorders.}, journal = {J Autism Dev Disord}, volume = {42}, year = {2012}, month = {2012 Dec}, pages = {2611-21}, abstract = {

Social referencing was investigated in 18-month-old siblings of children with autism spectrum disorders (ASD; "high-risk infants"). Infants were exposed to novel toys, which were emotionally tagged via adults{\textquoteright} facial and vocal signals. Infants{\textquoteright} information seeking (initiation of joint attention with an adult) and their approach/withdrawal behavior toward the toys before versus after the adults{\textquoteright} emotional signals was measured. Compared to both typically developing infants and high-risk infants without ASD, infants later diagnosed with ASD engaged in slower information seeking, suggesting that this aspect of referencing may be an early indicator of ASD. High-risk infants, both those who were and those who were not later diagnosed with ASD, exhibited impairments in regulating their behavior based on the adults{\textquoteright} emotional signals, suggesting that this aspect of social referencing may reflect an endophenotype for ASD.

}, keywords = {Attention, Child, Child Development, Child Development Disorders, Pervasive, Child, Preschool, Emotions, Endophenotypes, Female, Humans, Infant, Infant Behavior, Male, Risk Factors, Siblings, Social Behavior}, issn = {1573-3432}, doi = {10.1007/s10803-012-1518-8}, author = {Cornew, Lauren and Dobkins, Karen R and Akshoomoff, Natacha and McCleery, Joseph P and Carver, Leslie J} } @article {206, title = {Spatiotemporal neural dynamics of word understanding in 12- to 18-month-old-infants.}, journal = {Cereb Cortex}, volume = {21}, year = {2011}, month = {2011 Aug}, pages = {1832-9}, abstract = {

Learning words is central in human development. However, lacking clear evidence for how or where language is processed in the developing brain, it is unknown whether these processes are similar in infants and adults. Here, we use magnetoencephalography in combination with high-resolution structural magnetic resonance imaging to noninvasively estimate the spatiotemporal distribution of word-selective brain activity in 12- to 18-month-old infants. Infants watched pictures of common objects and listened to words that they understood. A subset of these infants also listened to familiar words compared with sensory control sounds. In both experiments, words evoked a characteristic event-related brain response peaking \~{}400 ms after word onset, which localized to left frontotemporal cortices. In adults, this activity, termed the N400m, is associated with lexico-semantic encoding. Like adults, we find that the amplitude of the infant N400m is also modulated by semantic priming, being reduced to words preceded by a semantically related picture. These findings suggest that similar left frontotemporal areas are used for encoding lexico-semantic information throughout the life span, from the earliest stages of word learning. Furthermore, this ontogenetic consistency implies that the neurophysiological processes underlying the N400m may be important both for understanding already known words and for learning new words.

}, keywords = {Adult, Brain Mapping, Cerebral Cortex, Evoked Potentials, Auditory, Female, Humans, Infant, Language Tests, Learning, Magnetic Resonance Imaging, Magnetoencephalography, Male, Neurons, Speech Perception, Vocabulary}, issn = {1460-2199}, doi = {10.1093/cercor/bhq259}, author = {Travis, Katherine E and Leonard, Matthew K and Brown, Timothy T and Hagler, Donald J and Curran, Megan and Dale, Anders M and Elman, Jeffrey L and Halgren, Eric} } @article {194, title = {Atypical face versus object processing and hemispheric asymmetries in 10-month-old infants at risk for autism.}, journal = {Biol Psychiatry}, volume = {66}, year = {2009}, month = {2009 Nov 15}, pages = {950-7}, abstract = {

BACKGROUND: Previous studies have documented atypicalities in face/object processing in children and adults with autism spectrum disorders (ASDs). To investigate whether such atypicalities may reflect a genetically mediated risk factor present early in development, we measured face/object processing in 10-month-old high-risk infants who carry some of the genes associated with ASD because they have an older sibling diagnosed with the disorder.

METHODS: We employed event-related potentials (ERPs) to measure cortical responses to pictures of faces and objects, the objects being toys. Latencies and amplitudes of four ERP components (P100, N290, P400, and Nc) were compared between 20 high-risk infants and 20 low-risk control subjects (infants with no family history of ASD).

RESULTS: Responses to faces versus objects differed between high- and low-risk infants for the latencies of the N290 and P400. Differences were driven by faster responses to faces than objects in low-risk, but not high-risk, infants (P400) and, conversely, faster responses to objects than faces in high-risk, but not low-risk, infants (N290). Object responses were also faster in high-risk than low-risk infants (both N290 and P400). Left versus right hemisphere responses also differed between high- and low-risk infants for the amplitudes of the P100, N290, and P400; collapsed across faces/objects, low-risk, but not high-risk, infants exhibited hemisphere asymmetries.

CONCLUSIONS: Genetic risk for ASD is associated with atypical face versus object processing and an atypical lack of hemispheric asymmetry early in life. These atypicalities might contribute to development of the disorder.

}, keywords = {Analysis of Variance, Autistic Disorder, Brain, Brain Mapping, Cerebral Cortex, Child, Child, Preschool, Electroencephalography, Evoked Potentials, Face, Female, Fourier Analysis, Functional Laterality, Humans, Infant, Male, Neuropsychological Tests, Pattern Recognition, Visual, Photic Stimulation, Reaction Time, Risk}, issn = {1873-2402}, doi = {10.1016/j.biopsych.2009.07.031}, author = {McCleery, Joseph P and Akshoomoff, Natacha and Dobkins, Karen R and Carver, Leslie J} } @article {184, title = {Effects of gestational length, gender, postnatal age, and birth order on visual contrast sensitivity in infants.}, journal = {J Vis}, volume = {9}, year = {2009}, month = {2009}, pages = {19.1-21}, abstract = {

To investigate effects of visual experience versus preprogrammed mechanisms on visual development, we used multiple regression analysis to determine the extent to which a variety of variables (that differ in the extent to which they are tied to visual experience) predict luminance and chromatic (red/green) contrast sensitivity (CS), which are mediated by the magnocellular (M) and parvocellular (P) subcortical pathways, respectively. Our variables included gestational length (GL), birth weight (BW), gender, postnatal age (PNA), and birth order (BO). Two-month-olds (n = 60) and 6-month-olds (n = 122) were tested. Results revealed that (1) at 2 months, infants with longer GL have higher luminance CS; (2) at both ages, CS significantly increases over a approximately 21-day range of PNA, but this effect is stronger in 2- than 6-month-olds and stronger for chromatic than luminance CS; (3) at 2 months, boys have higher luminance CS than girls; and (4) at 2 months, firstborn infants have higher CS, while at 6 months, non-firstborn infants have higher CS. The results for PNA/GL are consistent with the possibility that P pathway development is more influenced by variables tied to visual experience (PNA), while M pathway development is more influenced by variables unrelated to visual experience (GL). Other variables, including prenatal environment, are also discussed.

}, keywords = {Age Factors, Analysis of Variance, Birth Order, Color Perception, Contrast Sensitivity, Female, Gender Identity, Gestational Age, Humans, Infant, Light, Male, Regression Analysis}, issn = {1534-7362}, doi = {10.1167/9.10.19}, author = {Dobkins, Karen R and Bosworth, Rain G and McCleery, Joseph P} }