@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 = {<p>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.</p>
},
	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 {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 = {<p>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.</p>
},
	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}
}
