This study examines important developmental differences in patterns of activation in the prefront... more This study examines important developmental differences in patterns of activation in the prefrontal cortex during performance of a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned using gradient echo, echo planar imaging during performance of a response inhibition task. The results suggest four general findings. First, the location of activation in the prefrontal cortex was not different between children and adults, which is similar to our earlier pediatric fMRI results of prefrontal activation during a working memory task (Casey et al., 1995). Second, the volume of activation was significantly greater for children relative to adults. These differences in volume of activation were observed predominantly in the dorsal and lateral prefrontal cortices. Third, although inhibitory processes have typically been associated with more ventral or orbital frontal regions, the current study revealed activation that was distributed across both dorsolateral and orbitofrontal cortices. Finally, consistent with animal and human lesion studies, activity in orbital frontal and anterior cingulate cortices correlated with behavioral performance (i.e., number of false alarms). These results further demonstrate the utility of this methodology in studying pediatric populations.
Construct definitions of empathy have sought to distinguish between different dimensions of empat... more Construct definitions of empathy have sought to distinguish between different dimensions of empathetic capacity that are significantly associated with psychological distress or wellbeing. Research has provided substantial evidence differentiating affective and cognitive empathy; however, more recent research has cited the importance of a third domain represented by empathetic behaviors and compassionate intent to comfort others. Examining developmental and maturational stage during the rapid transitional period of early adolescence is needed to model developmental trajectories, mechanisms of change and mental health outcomes. This study aims to assess relationships between pubertal developmental stage, dimensions of empathy, and depression, anxiety and externalizing behaviors among early adolescents. A cross-sectional survey among young adolescents ages 9–12 years was conducted in Dar es Salaam, Tanzania. The relationships between pubertal developmental stage, affective, cognitive, ...
Published paper can be found at https://doi.org/10.1111/jora.12781. This study aimed to examine c... more Published paper can be found at https://doi.org/10.1111/jora.12781. This study aimed to examine changes in depression and anxiety symptoms from before to during the first six months of the COVID-19 pandemic in a sample of 1,339 adolescents from three countries (9-18 years old, 59% female). We also examined if age, race/ethnicity, disease burden, or strictness of government restrictions moderated change in symptoms. Data from 12 longitudinal studies (10 U.S., 1 Netherlands, 1 Peru) were combined. Linear mixed effect models showed that depression symptoms increased significantly (median increase=28%), whereas anxiety symptoms remained stable overall. The most negative mental health impacts were reported by multiracial adolescents and those under ‘lockdown’ restrictions. Policy makers need to consider these impacts by investing in ways to support adolescents’ mental health during the pandemic.
BACKGROUND The onset of puberty is a pivotal period of human development that is associated with ... more BACKGROUND The onset of puberty is a pivotal period of human development that is associated with significant changes in cognitive, social, emotional, psychological, and behavioral processes that shape identity formation. Very early adolescence provides a critical opportunity to shape identity formation around gender norms, attitudes, and beliefs before inequitable gender norms are amplified during and after puberty. OBJECTIVE The aim of the Discover Learning Project is to integrate strategic insights from developmental science to promote positive transformation in social, emotional, and gender identity learning among 10- to 11-year-olds in Tanzania. Through a pragmatic randomized controlled trial, the intervention scaffolds the development of critical social and emotional mindsets and skills (curiosity, generosity, persistence, purpose, growth mindset, and teamwork) delivered by conducting 18 after-school, technology-driven, experiential learning sessions in small, mixed-gender grou...
Multiple neurocognitive systems contribute simultaneously to learning. For example, dopamine and ... more Multiple neurocognitive systems contribute simultaneously to learning. For example, dopamine and basal ganglia (BG) systems are thought to support reinforcement learning (RL) by incrementally updating the value of choices, while the prefrontal cortex (PFC) contributes different computations, such as actively maintaining precise information in working memory (WM). It is commonly thought that WM and PFC show more protracted development than RL and BG systems, yet their contributions are rarely assessed in tandem. Here, we used a simple learning task to test how RL and WM contribute to changes in learning across adolescence. We tested 187 subjects ages 8 to 17 and 53 adults (25-30). Participants learned stimulus-action associations from feedback; the learning load was varied to be within or exceed WM capacity. Participants age 8-12 learned slower than participants age 13-17, and were more sensitive to load. We used computational modeling to estimate subjects’ use of WM and RL processes...
The developmental patterns of subcortical brain volumes in males and females observed in previous... more The developmental patterns of subcortical brain volumes in males and females observed in previous studies have been inconsistent. To help resolve these discrepancies, we examined developmental trajectories in three independent longitudinal samples of participants with the age-span of 8-22 years (total 216 participants and 467 scans). These datasets, including Pittsburgh (PIT; University of Pittsburgh, USA), NeuroCognitive Development (NCD; University of Oslo, Norway), and Orygen Adolescent Development Study (OADS; The University of Melbourne, Australia), span three countries and were analyzed in parallel using mixed-effects modeling with both generalized additive models and general linear models. The results showed that absolute volume estimates largely overlapped across samples for the thalamus, caudate, putamen, hippocampus, and amygdala in each sex, whereas volumes were less consistent across samples for the pallidum and nucleus accumbens. In males, the thalamus showed increasing...
The current study examines the association between parental support and adolescent sleep under va... more The current study examines the association between parental support and adolescent sleep under varying levels of family stress. Participants included 316 adolescents (Mage = 16.40 years, 43% male) and their parents (Mage = 45.67 years, 91% mothers) from diverse ethnic backgrounds. Both adolescents and parents completed questionnaires and adolescents wore wrist actigraphs and completed self-reports on their sleep for 7 consecutive days. Results indicated that under contexts of family stress, more parental support was linked to longer sleep duration, less sleep variability, and less time spent awake during the night. Findings suggest that under contexts of family stress, cohesive family relationships may provide a sense of stability and security that is necessary for healthful sleep.
Adolescence is a developmental period characterized by a greater tendency to take risks. While th... more Adolescence is a developmental period characterized by a greater tendency to take risks. While the adult literature has shown that sex steroids influence reward-related brain functioning and risk taking, research on the role of these hormones during puberty is limited. In this study, we examined the relation between pubertal hormones and adolescent risk taking using a probabilistic decision-making task. In this task, participants could choose on each trial to play or pass based on explicit information about the risk level and stakes involved in their decision. We administered this task to 58 11-to-13-year-old girls while functional MRI images were obtained to examine reward-related brain processes associated with their risky choices. Results showed that higher testosterone levels were associated with increased risk taking, which was mediated by increased medial orbitofrontal cortex activation. Furthermore, higher estradiol levels were associated with increased nucleus accumbens acti...
To investigate the associations between objective and subjective dimensions of adolescent sleep a... more To investigate the associations between objective and subjective dimensions of adolescent sleep and C-reactive protein (CRP), a key biomarker of inflammation that predicts chronic health problems in adulthood, and whether the associations vary as a function of adolescents' age. A total of 315 adolescents (14.5-18.4 years) wore wrist actigraphs at night to objectively estimate their sleep duration and variability across nights, and completed the Pittsburgh Sleep Quality Index to assess their subjective sleep quality. CRP levels were assayed from dried blood spots obtained from finger pricks. To control for adiposity, age- and sex-specific body mass index percentiles were obtained from height and weight measurements. Nightly variability in sleep duration was associated with higher levels of CRP (b = 0.13, p = .045). Shorter average sleep duration was associated with higher CRP, but only among younger adolescents (b = -0.11, p = .041). Subjective sleep quality was not associated wi...
Sleep problems are a major risk factor for the emergence of depression in adolescence. The aim of... more Sleep problems are a major risk factor for the emergence of depression in adolescence. The aim of this study was to test whether an intervention for improving sleep habits could prevent the emergence of depression, and improve well-being and cardiovascular indices amongst at-risk adolescents. A longitudinal randomised controlled trial (RCT) is being conducted across Victorian Secondary Schools in Melbourne, Australia. Adolescents (aged 12-17 years) were defined as at-risk for depression if they reported high levels of anxiety and sleep problems on in-school screening questionnaires and had no prior history of depression (assessed by clinical diagnostic interview). Eligible participants were randomised into either a sleep improvement intervention (based on cognitive behavioral and mindfulness principles) or an active control condition teaching study skills. Both programs consisted of seven 90 minute-long sessions over seven weeks. All participants were required to complete a battery ...
The onset of adolescence is associated with an increase in the behavioral tendency to explore and... more The onset of adolescence is associated with an increase in the behavioral tendency to explore and seek novel experiences. However, this exploration has rarely been quantified, and its neural correlates during this period remain unclear. Previously, activity within specific regions of the rostrolateral pFC (rlPFC) in adults has been shown to correlate with the tendency for exploration. Here we investigate a recently developed task to assess individual differences in strategic exploration, defined as the degree to which the relative uncertainty of rewards directs responding toward less well-evaluated choices, in 62 girls aged 11-13 years from whom resting state fMRI data were obtained in a separate session. Behaviorally, this task divided our participants into groups of explorers (n = 41) and nonexplorers (n = 21). When seed ROIs within the rlPFC were used to interrogate resting state fMRI data, we identified a lateralized connection between the rlPFC and posterior putamen/insula whos...
This study examines important developmental differences in patterns of activation in the prefront... more This study examines important developmental differences in patterns of activation in the prefrontal cortex during performance of a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned using gradient echo, echo planar imaging during performance of a response inhibition task. The results suggest four general findings. First, the location of activation in the prefrontal cortex was not different between children and adults, which is similar to our earlier pediatric fMRI results of prefrontal activation during a working memory task (Casey et al., 1995). Second, the volume of activation was significantly greater for children relative to adults. These differences in volume of activation were observed predominantly in the dorsal and lateral prefrontal cortices. Third, although inhibitory processes have typically been associated with more ventral or orbital frontal regions, the current study revealed activation that was distributed across both dorsolateral and orbitofrontal cortices. Finally, consistent with animal and human lesion studies, activity in orbital frontal and anterior cingulate cortices correlated with behavioral performance (i.e., number of false alarms). These results further demonstrate the utility of this methodology in studying pediatric populations.
Construct definitions of empathy have sought to distinguish between different dimensions of empat... more Construct definitions of empathy have sought to distinguish between different dimensions of empathetic capacity that are significantly associated with psychological distress or wellbeing. Research has provided substantial evidence differentiating affective and cognitive empathy; however, more recent research has cited the importance of a third domain represented by empathetic behaviors and compassionate intent to comfort others. Examining developmental and maturational stage during the rapid transitional period of early adolescence is needed to model developmental trajectories, mechanisms of change and mental health outcomes. This study aims to assess relationships between pubertal developmental stage, dimensions of empathy, and depression, anxiety and externalizing behaviors among early adolescents. A cross-sectional survey among young adolescents ages 9–12 years was conducted in Dar es Salaam, Tanzania. The relationships between pubertal developmental stage, affective, cognitive, ...
Published paper can be found at https://doi.org/10.1111/jora.12781. This study aimed to examine c... more Published paper can be found at https://doi.org/10.1111/jora.12781. This study aimed to examine changes in depression and anxiety symptoms from before to during the first six months of the COVID-19 pandemic in a sample of 1,339 adolescents from three countries (9-18 years old, 59% female). We also examined if age, race/ethnicity, disease burden, or strictness of government restrictions moderated change in symptoms. Data from 12 longitudinal studies (10 U.S., 1 Netherlands, 1 Peru) were combined. Linear mixed effect models showed that depression symptoms increased significantly (median increase=28%), whereas anxiety symptoms remained stable overall. The most negative mental health impacts were reported by multiracial adolescents and those under ‘lockdown’ restrictions. Policy makers need to consider these impacts by investing in ways to support adolescents’ mental health during the pandemic.
BACKGROUND The onset of puberty is a pivotal period of human development that is associated with ... more BACKGROUND The onset of puberty is a pivotal period of human development that is associated with significant changes in cognitive, social, emotional, psychological, and behavioral processes that shape identity formation. Very early adolescence provides a critical opportunity to shape identity formation around gender norms, attitudes, and beliefs before inequitable gender norms are amplified during and after puberty. OBJECTIVE The aim of the Discover Learning Project is to integrate strategic insights from developmental science to promote positive transformation in social, emotional, and gender identity learning among 10- to 11-year-olds in Tanzania. Through a pragmatic randomized controlled trial, the intervention scaffolds the development of critical social and emotional mindsets and skills (curiosity, generosity, persistence, purpose, growth mindset, and teamwork) delivered by conducting 18 after-school, technology-driven, experiential learning sessions in small, mixed-gender grou...
Multiple neurocognitive systems contribute simultaneously to learning. For example, dopamine and ... more Multiple neurocognitive systems contribute simultaneously to learning. For example, dopamine and basal ganglia (BG) systems are thought to support reinforcement learning (RL) by incrementally updating the value of choices, while the prefrontal cortex (PFC) contributes different computations, such as actively maintaining precise information in working memory (WM). It is commonly thought that WM and PFC show more protracted development than RL and BG systems, yet their contributions are rarely assessed in tandem. Here, we used a simple learning task to test how RL and WM contribute to changes in learning across adolescence. We tested 187 subjects ages 8 to 17 and 53 adults (25-30). Participants learned stimulus-action associations from feedback; the learning load was varied to be within or exceed WM capacity. Participants age 8-12 learned slower than participants age 13-17, and were more sensitive to load. We used computational modeling to estimate subjects’ use of WM and RL processes...
The developmental patterns of subcortical brain volumes in males and females observed in previous... more The developmental patterns of subcortical brain volumes in males and females observed in previous studies have been inconsistent. To help resolve these discrepancies, we examined developmental trajectories in three independent longitudinal samples of participants with the age-span of 8-22 years (total 216 participants and 467 scans). These datasets, including Pittsburgh (PIT; University of Pittsburgh, USA), NeuroCognitive Development (NCD; University of Oslo, Norway), and Orygen Adolescent Development Study (OADS; The University of Melbourne, Australia), span three countries and were analyzed in parallel using mixed-effects modeling with both generalized additive models and general linear models. The results showed that absolute volume estimates largely overlapped across samples for the thalamus, caudate, putamen, hippocampus, and amygdala in each sex, whereas volumes were less consistent across samples for the pallidum and nucleus accumbens. In males, the thalamus showed increasing...
The current study examines the association between parental support and adolescent sleep under va... more The current study examines the association between parental support and adolescent sleep under varying levels of family stress. Participants included 316 adolescents (Mage = 16.40 years, 43% male) and their parents (Mage = 45.67 years, 91% mothers) from diverse ethnic backgrounds. Both adolescents and parents completed questionnaires and adolescents wore wrist actigraphs and completed self-reports on their sleep for 7 consecutive days. Results indicated that under contexts of family stress, more parental support was linked to longer sleep duration, less sleep variability, and less time spent awake during the night. Findings suggest that under contexts of family stress, cohesive family relationships may provide a sense of stability and security that is necessary for healthful sleep.
Adolescence is a developmental period characterized by a greater tendency to take risks. While th... more Adolescence is a developmental period characterized by a greater tendency to take risks. While the adult literature has shown that sex steroids influence reward-related brain functioning and risk taking, research on the role of these hormones during puberty is limited. In this study, we examined the relation between pubertal hormones and adolescent risk taking using a probabilistic decision-making task. In this task, participants could choose on each trial to play or pass based on explicit information about the risk level and stakes involved in their decision. We administered this task to 58 11-to-13-year-old girls while functional MRI images were obtained to examine reward-related brain processes associated with their risky choices. Results showed that higher testosterone levels were associated with increased risk taking, which was mediated by increased medial orbitofrontal cortex activation. Furthermore, higher estradiol levels were associated with increased nucleus accumbens acti...
To investigate the associations between objective and subjective dimensions of adolescent sleep a... more To investigate the associations between objective and subjective dimensions of adolescent sleep and C-reactive protein (CRP), a key biomarker of inflammation that predicts chronic health problems in adulthood, and whether the associations vary as a function of adolescents' age. A total of 315 adolescents (14.5-18.4 years) wore wrist actigraphs at night to objectively estimate their sleep duration and variability across nights, and completed the Pittsburgh Sleep Quality Index to assess their subjective sleep quality. CRP levels were assayed from dried blood spots obtained from finger pricks. To control for adiposity, age- and sex-specific body mass index percentiles were obtained from height and weight measurements. Nightly variability in sleep duration was associated with higher levels of CRP (b = 0.13, p = .045). Shorter average sleep duration was associated with higher CRP, but only among younger adolescents (b = -0.11, p = .041). Subjective sleep quality was not associated wi...
Sleep problems are a major risk factor for the emergence of depression in adolescence. The aim of... more Sleep problems are a major risk factor for the emergence of depression in adolescence. The aim of this study was to test whether an intervention for improving sleep habits could prevent the emergence of depression, and improve well-being and cardiovascular indices amongst at-risk adolescents. A longitudinal randomised controlled trial (RCT) is being conducted across Victorian Secondary Schools in Melbourne, Australia. Adolescents (aged 12-17 years) were defined as at-risk for depression if they reported high levels of anxiety and sleep problems on in-school screening questionnaires and had no prior history of depression (assessed by clinical diagnostic interview). Eligible participants were randomised into either a sleep improvement intervention (based on cognitive behavioral and mindfulness principles) or an active control condition teaching study skills. Both programs consisted of seven 90 minute-long sessions over seven weeks. All participants were required to complete a battery ...
The onset of adolescence is associated with an increase in the behavioral tendency to explore and... more The onset of adolescence is associated with an increase in the behavioral tendency to explore and seek novel experiences. However, this exploration has rarely been quantified, and its neural correlates during this period remain unclear. Previously, activity within specific regions of the rostrolateral pFC (rlPFC) in adults has been shown to correlate with the tendency for exploration. Here we investigate a recently developed task to assess individual differences in strategic exploration, defined as the degree to which the relative uncertainty of rewards directs responding toward less well-evaluated choices, in 62 girls aged 11-13 years from whom resting state fMRI data were obtained in a separate session. Behaviorally, this task divided our participants into groups of explorers (n = 41) and nonexplorers (n = 21). When seed ROIs within the rlPFC were used to interrogate resting state fMRI data, we identified a lateralized connection between the rlPFC and posterior putamen/insula whos...
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Papers by Ronald Dahl