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1.  Entering Adolescence: Resistance to Peer Influence, Risky Behavior, and Neural Changes in Emotion Reactivity 
Neuron  2011;69(5):10.1016/j.neuron.2011.02.019.
SUMMARY
Adolescence is often described as a period of heightened reactivity to emotions paired with reduced regulatory capacities, a combination suggested to contribute to risk-taking and susceptibility to peer influence during puberty. However, no longitudinal research has definitively linked these behavioral changes to underlying neural development. Here, 38 neurotypical participants underwent two fMRI sessions across the transition from late childhood (10 years) to early adolescence (13 years). Responses to affective facial displays exhibited a combination of general and emotion-specific changes in ventral striatum (VS), ventromedial PFC, amygdala, and temporal pole. Furthermore, VS activity increases correlated with decreases in susceptibility to peer influence and risky behavior. VS and amygdala responses were also significantly more negatively coupled in early adolescence than in late childhood while processing sad and happy versus neutral faces. Together, these results suggest that VS responses to viewing emotions may play a regulatory role that is critical to adolescent interpersonal functioning.
doi:10.1016/j.neuron.2011.02.019
PMCID: PMC3840168  PMID: 21382560
2.  Mirroring others’ emotions relates to empathy and interpersonal competence in children 
NeuroImage  2007;39(4):10.1016/j.neuroimage.2007.10.032.
The mirror neuron system (MNS) has been proposed to play an important role in social cognition by providing a neural mechanism by which others’ actions, intentions, and emotions can be understood. Here functional magnetic resonance imaging was used to directly examine the relationship between MNS activity and two distinct indicators of social functioning in typically-developing children (aged 10.1 years±7 months): empathy and interpersonal competence. Reliable activity in pars opercularis, the frontal component of the MNS, was elicited by observation and imitation of emotional expressions. Importantly, activity in this region (as well as in the anterior insula and amygdala) was significantly and positively correlated with established behavioral measures indexing children’s empathic behavior (during both imitation and observation) and interpersonal skills (during imitation only). These findings suggest that simulation mechanisms and the MNS may indeed be relevant to social functioning in everyday life during typical human development.
doi:10.1016/j.neuroimage.2007.10.032
PMCID: PMC3840169  PMID: 18082427
3.  Longitudinal change in the neural bases of adolescent social self-evaluations: Effects of age and pubertal development 
Self-evaluations undergo significant transformation during early adolescence, developing in parallel with the heightened complexity of teenagers’ social worlds. Intuitive theories of adolescent development, based in part on animal work, suggest that puberty is associated with neural-level changes that facilitate a “social reorientation” (Nelson, Leibenluft, McClure, and Pine, 2005). However, direct tests of this hypothesis using neuroimaging are limited in humans. This longitudinal fMRI study examined neurodevelopmental trajectories associated with puberty, self-evaluations, and the presumed social reorientation during the transition from childhood to adolescence. Participants (N = 27, M age = 10.1 and 13.1 years at timepoints one and two, respectively) engaged in trait evaluations of two targets (the self and a familiar fictional other), across two domains of competence (social and academic). Responses in ventromedial PFC increased with both age and pubertal development during self-evaluations in the social domain, but not in the academic domain. These results suggest changes in social self-evaluations are intimately connected with biology, not just peer contexts, and provide important empirical support for the relationship between neurodevelopment, puberty, and social functioning.
doi:10.1523/JNEUROSCI.4074-12.2013
PMCID: PMC3809090  PMID: 23616547
4.  Age and experience shape developmental changes in the neural basis of language-related learning 
Developmental science  2011;14(6):1261-1282.
Very little is known about the neural underpinnings of language learning across the lifespan and how these might be modified by maturational and experiential factors. Building on behavioral research highlighting the importance of early word segmentation (i.e. the detection of word boundaries in continuous speech) for subsequent language learning, here we characterize developmental changes in brain activity as this process occurs online, using data collected in a mixed cross-sectional and longitudinal design. One hundred and fifty-six participants, ranging from age 5 to adulthood, underwent functional magnetic resonance imaging (fMRI) while listening to three novel streams of continuous speech, which contained either strong statistical regularities, strong statistical regularities and speech cues, or weak statistical regularities providing minimal cues to word boundaries. All age groups displayed significant signal increases over time in temporal cortices for the streams with high statistical regularities; however, we observed a significant right-to-left shift in the laterality of these learning-related increases with age. Interestingly, only the 5- to 10-year-old children displayed significant signal increases for the stream with low statistical regularities, suggesting an age-related decrease in sensitivity to more subtle statistical cues. Further, in a sample of 78 10-year-olds, we examined the impact of proficiency in a second language and level of pubertal development on learning-related signal increases, showing that the brain regions involved in language learning are influenced by both experiential and maturational factors.
doi:10.1111/j.1467-7687.2011.01075.x
PMCID: PMC3717169  PMID: 22010887
5.  Cracking the Language Code: Neural Mechanisms Underlying Speech Parsing 
Word segmentation, detecting word boundaries in continuous speech, is a critical aspect of language learning. Previous research in infants and adults demonstrated that a stream of speech can be readily segmented based solely on the statistical and speech cues afforded by the input. Using functional magnetic resonance imaging (fMRI), the neural substrate of word segmentation was examined on-line as participants listened to three streams of concatenated syllables, containing either statistical regularities alone, statistical regularities and speech cues, or no cues. Despite the participants’ inability to explicitly detect differences between the speech streams, neural activity differed significantly across conditions, with left-lateralized signal increases in temporal cortices observed only when participants listened to streams containing statistical regularities, particularly the stream containing speech cues. In a second fMRI study, designed to verify that word segmentation had implicitly taken place, participants listened to trisyllabic combinations that occurred with different frequencies in the streams of speech they just heard (“words,” 45 times; “partwords,” 15 times; “nonwords,” once). Reliably greater activity in left inferior and middle frontal gyri was observed when comparing words with partwords and, to a lesser extent, when comparing partwords with nonwords. Activity in these regions, taken to index the implicit detection of word boundaries, was positively correlated with participants’ rapid auditory processing skills. These findings provide a neural signature of on-line word segmentation in the mature brain and an initial model with which to study developmental changes in the neural architecture involved in processing speech cues during language learning.
doi:10.1523/JNEUROSCI.5501-05.2006
PMCID: PMC3713232  PMID: 16855090
fMRI; language; speech perception; word segmentation; statistical learning; auditory cortex; inferior frontal gyrus
6.  Facing puberty: associations between pubertal development and neural responses to affective facial displays 
Adolescence is marked by profound psychosocial and physiological changes. Although investigations into the interactions between these forces have begun to shed light on the neural correlates of affective processing during the transition to adolescence, relatively little is known about the relationship between pubertal development and emotion perception at the neural level. In the current longitudinal study, 45 neurotypical participants were shown affective facial displays while undergoing fMRI, at ages 10 and 13. Neural responses to emotional expressions at both time points were then correlated with a self-report measure of pubertal development, revealing positive associations with activity in amygdala, thalamus and visual cortical areas at age 10 that increased in magnitude and extent by age 13. At the latter time point, pubertal development was additionally correlated with enhanced responses to faces in temporal pole, ventrolateral prefrontal cortex (PFC) and dorsomedial PFC. Longitudinal comparisons revealed that the relationships between pubertal development and activity in the amygdala, hippocampus and temporal pole were significantly stronger during early adolescence than late childhood. These results suggest that pubertal development per se is linked to neural processing of socioemotional stimuli, particularly with respect to the integration of complex perceptual input and higher order cortical processing of affective content.
doi:10.1093/scan/nsr066
PMCID: PMC3252633  PMID: 22228752
adolescence; puberty; emotion; fMRI; amygdala; longitudinal
7.  The Neural Basis of Speech Parsing in Children and Adults 
Developmental science  2010;13(2):385-406.
Word segmentation, detecting word boundaries in continuous speech, is a fundamental aspect of language learning that can occur solely by the computation of statistical and speech cues. Fifty-four children underwent functional magnetic resonance imaging (fMRI) while listening to three streams of concatenated syllables, which contained either high statistical regularities, high statistical regularities and speech cues, or no easily-detectable cues. Significant signal increases over time in temporal cortices suggest that children utilized the cues to implicitly segment the speech streams. This was confirmed by the findings of a second fMRI run where children displayed reliably greater activity in left inferior frontal gyrus when listening to ‘words’ that occurred more frequently in the streams of speech they just heard. Finally, comparisons between activity observed in these children vs. previously-studied adults indicate significant developmental changes in the neural substrate of speech parsing.
doi:10.1111/j.1467-7687.2009.00895.x
PMCID: PMC3229831  PMID: 20136936
fMRI; language; development; speech perception; word segmentation; statistical learning
8.  Neural correlates of social exclusion during adolescence: understanding the distress of peer rejection 
Developmental research has demonstrated the harmful effects of peer rejection during adolescence; however, the neural mechanisms responsible for this salience remain unexplored. In this study, 23 adolescents were excluded during a ball-tossing game in which they believed they were playing with two other adolescents during an fMRI scan; in reality, participants played with a preset computer program. Afterwards, participants reported their exclusion-related distress and rejection sensitivity, and parents reported participants’ interpersonal competence. Similar to findings in adults, during social exclusion adolescents displayed insular activity that was positively related to self-reported distress, and right ventrolateral prefrontal activity that was negatively related to self-reported distress. Findings unique to adolescents indicated that activity in the subgenual anterior cingulate cortex (subACC) related to greater distress, and that activity in the ventral striatum related to less distress and appeared to play a role in regulating activity in the subACC and other regions involved in emotional distress. Finally, adolescents with higher rejection sensitivity and interpersonal competence scores displayed greater neural evidence of emotional distress, and adolescents with higher interpersonal competence scores also displayed greater neural evidence of regulation, perhaps suggesting that adolescents who are vigilant regarding peer acceptance may be most sensitive to rejection experiences.
doi:10.1093/scan/nsp007
PMCID: PMC2686232  PMID: 19470528
peer rejection; adolescence; functional magnetic resonance imaging

Results 1-8 (8)