Adolescent substance use and functional connectivity between the ventral striatum and hippocampus

Effects of gaming content from social media on individuals with internet gaming disorder: an fMRI study

Internet gaming disorder is an increasing public health problem due to the widespread availability of online gaming. Social media platforms drive this trend by enabling gameplay sharing and increasing user engagement, potentially reinforcing addictive gaming behaviors. Understanding how gaming content exposure on social media affects brain activity in individuals with internet gaming disorder is crucial. This study aimed to investigate gaming content neural responses on social media in individuals with internet gaming disorder using functional magnetic resonance imaging. We aimed to determine differences in activation patterns that contribute to understanding the neurobiological underpinnings of internet gaming disorder by examining brain activity in these individuals and comparing it to healthy controls. Additionally, we investigated the association of brain activity with clinical characteristics (internet gaming disorder severity and illness duration). The participants with internet gaming disorder demonstrated increased bilateral orbitofrontal cortex, bilateral hippocampus, left precuneus, and right superior temporal gyrus activation in response to gaming-related cues on social media compared to healthy controls. Additionally, internet gaming disorder severity and illness duration correlated with left hippocampus activation levels. These results improve our understanding of how gaming-related content on social media affects individuals with internet gaming disorder. Our findings provide valuable information into the neurobiological features of internet gaming disorder and help develop effective treatment interventions.

The promise of precision functional mapping for neuroimaging in psychiatry

Precision functional mapping (PFM) is a neuroimaging approach to reliably estimate metrics of brain function from individual people via the collection of large amounts of fMRI data (hours per person). This method has revealed much about the inter-individual variation of functional brain networks. While standard group-level studies, in which we average brain measures across groups of people, are important in understanding the generalizable neural underpinnings of neuropsychiatric disorders, many disorders are heterogeneous in nature. This heterogeneity often complicates clinical care, leading to patient uncertainty when considering prognosis or treatment options. We posit that PFM methods may help streamline clinical care in the future, fast-tracking the choice of personalized treatment that is most compatible with the individual. In this review, we provide a history of PFM studies, foundational results highlighting the benefits of PFM methods in the pursuit of an advanced understanding of individual differences in functional network organization, and possible avenues where PFM can contribute to clinical translation of neuroimaging research results in the way of personalized treatment in psychiatry.

A longitudinal study of the relationship between alcohol-related blackouts and attenuated structural brain development

PURPOSE

Alcohol-related blackouts (ARBs) are common in adolescents and emerging adults. ARBs may also be indicative of persistent, alcohol-related neurocognitive changes. This study explored ARBs as a predictor of altered structural brain development and associated cognitive correlates.

METHODS

Longitudinal growth curve modeling estimated trajectories of brain volume across 6 years in participants from the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study (n = 800, 213 with lifetime ARB history). While controlling for demographics and overall alcohol use, ARB history was analyzed as a predictor of brain volume growth in regions associated with alcohol-related cognitive change. Post hoc analyses examined whether ARBs moderated relationships between brain morphology and cognition.

RESULTS

ARBs significantly predicted attenuated development of fusiform gyrus and hippocampal volume at unique timepoints compared to overall alcohol use. Alcohol use without ARBs significantly predicted attenuated fusiform and hippocampal growth at earlier and later timepoints, respectively. Despite altered development in regions associated with memory, ARBs did not significantly moderate relationships between brain volume and cognitive performance.

CONCLUSION

ARBs and overall alcohol use predicted altered brain development in the fusiform gyrus and hippocampus at different timepoints, suggesting ARBs represent a unique marker of neurocognitive risk in younger drinkers.

Functional Connectivity of the Nucleus Accumbens across Variants of Callous-Unemotional Traits: A Resting-State fMRI Study in Children and Adolescents

A large body of literature suggests that the primary (high callousness-unemotional traits [CU] and low anxiety) and secondary (high CU traits and anxiety) variants of psychopathy significantly differ in terms of their clinical profiles. However, little is known about their neurobiological differences. While few studies showed that variants differ in brain activity during fear processing, it remains unknown whether they also show atypical functioning in motivational and reward system. Latent Profile Analysis (LPA) was conducted on a large sample of adolescents (n = 1416) to identify variants based on their levels of callousness and anxiety. Seed-to-voxel connectivity analysis was subsequently performed on resting-state fMRI data to compare connectivity patterns of the nucleus accumbens across subgroups. LPA failed to identify the primary variant when using total score of CU traits. Using a family-wise cluster correction, groups did not differ on functional connectivity. However, at an uncorrected threshold the secondary variant showed distinct functional connectivity between the nucleus accumbens and posterior insula, lateral orbitofrontal cortex, supplementary motor area, and parietal regions. Secondary LPA analysis using only the callousness subscale successfully distinguish both variants. Group differences replicated results of deficits in functional connectivity between the nucleus accumbens and posterior insula and supplementary motor area, but additionally showed effect in the superior temporal gyrus which was specific to the primary variant. The current study supports the importance of examining the neurobiological markers across subgroups of adolescents at risk for conduct problems to precise our understanding of this heterogeneous population.

Hippocampal anterior- posterior shift in childhood and adolescence

Hippocampal-cortical networks play an important role in neurocognitive development. Applying the method of Connectivity-Based Parcellation (CBP) on hippocampal-cortical structural covariance (SC) networks computed from T1-weighted magnetic resonance images, we examined how the hippocampus differentiates into subregions during childhood and adolescence (N = 1105, 6-18 years). In late childhood, the hippocampus mainly differentiated along the anterior-posterior axis similar to previous reported functional differentiation patterns of the hippocampus. In contrast, in adolescence a differentiation along the medial-lateral axis was evident, reminiscent of the cytoarchitectonic division into cornu ammonis and subiculum. Further meta-analytical characterization of hippocampal subregions in terms of related structural co-maturation networks, behavioural and gene profiling suggested that the hippocampal head is related to higher order functions (e.g. language, theory of mind, autobiographical memory) in late childhood morphologically co-varying with almost the whole brain. In early adolescence but not in childhood, posterior subicular SC networks were associated with action-oriented and reward systems. The findings point to late childhood as an important developmental period for hippocampal head morphology and to early adolescence as a crucial period for hippocampal integration into action- and reward-oriented cognition. The latter may constitute a developmental feature that conveys increased propensity for addictive disorders.

Adolescent social isolation induced alterations in nucleus accumbens glutamate signalling

Exposure to adversity during early childhood and adolescence increases an individual's vulnerability to developing substance use disorder. Despite the knowledge of this vulnerability, the mechanisms underlying it are still poorly understood. Excitatory afferents to the nucleus accumbens (NAc) mediate responses to both stressful and rewarding stimuli. Understanding how adolescent social isolation alters these afferents could inform the development of targeted interventions both before and after drug use. Here, we used social isolation rearing as a model of early life adversity which we have previously demonstrated increases vulnerability to cocaine addiction-like behaviour. The current study examined the effect of social isolation rearing on presynaptic glutamatergic transmission in NAc medium spiny neurons in both male and female mice. We show that social isolation rearing alters presynaptic plasticity in the NAc by decreasing the paired-pulse ratio and the size of the readily releasable pool of glutamate. Optogenetically activating the glutamatergic input from the ventral hippocampus to the NAc is sufficient to recapitulate the decreases in paired-pulse ratio and readily releasable pool size seen following electrical stimulation of all NAc afferents. Further, optogenetically inhibiting the ventral hippocampal afferent during electrical stimulation eliminates the effect of early life adversity on the paired-pulse ratio or readily releasable pool size. In summary, we demonstrate that social isolation rearing leads to alterations in glutamate transmission driven by projections from the ventral hippocampus. These data suggest that targeting the circuit from the ventral hippocampus to the nucleus accumbens could provide a means to reverse stress-induced plasticity.

Ventral striatal resting-state functional connectivity in adolescents is associated with earlier onset of binge drinking

BACKGROUND

Earlier engagement in heavy drinking during adolescence is a risk factor for the development of alcohol use disorders later in life. Longitudinal studies in adolescents have linked brain structure and task-evoked function to future alcohol use; however, less is known about how intrinsic network-level interactions relate to future substance use during this developmental period.

METHODS

In this prospective longitudinal study, resting-state functional connectivity of the ventral striatum, risky decision making, and sensation seeking were measured in 73 adolescents at baseline. Participants were between the ages of 14 and 15 and had no substantial history of substance use upon study entry. Follow-up interviews were conducted approximately every 3 months to assess the initiation of binge drinking (≥ 5 or ≥ 4 drinks per occasion for males or females, respectively).

RESULTS

Adolescents who began binge drinking sooner exhibited greater connectivity of the ventral striatum to the left precuneus, left angular gyrus, and the left superior frontal gyrus. Greater connectivity of the ventral striatum to the right insula/putamen was associated with longer duration to the onset of binge drinking. Resting-state functional connectivity in these regions was not associated with baseline assessments of risky decision making or sensation seeking.

CONCLUSIONS

Findings provide novel information about potential risk factors for early initiation of heavy alcohol use. Interventions that target relevant resting-state networks may enhance prevention efforts to decrease adolescent substance use by prolonging onset to heavier levels of alcohol consumption.