Critical tests of fuzzy trace theory in brain and behavior: uncertainty across time, probability, and development

Uncertainty permeates decisions from the trivial to the profound. Integrating brain and behavioral evidence, we discuss how probabilistic (varied outcomes) and temporal (delayed outcomes) uncertainty differ across age and individuals; how critical tests adjudicate between theories of uncertainty (prospect theory and fuzzy-trace theory); and how these mechanisms might be represented in the brain. The same categorical gist representations of gains and losses account for choices and eye-tracking data in both value-allocation (add money to gambles) and risky-choice tasks, disconfirming prospect theory and confirming predictions of fuzzy-trace theory. The analysis is extended to delay discounting and disambiguated choices, explaining hidden-zero effects that similarly turn on categorical distinctions between some gain and no gain, certain gain and uncertain gain, gain and loss, and now and later. Bold activation implicates dorsolateral prefrontal and posterior parietal cortices in gist strategies that are not just one tool in a grab-bag of cognitive options but rather are general strategies that systematically predict behaviors across many different tasks involving probabilistic and temporal uncertainty. High valuation (e.g., ventral striatum; ventromedial prefrontal cortex) and low executive control (e.g., lateral prefrontal cortex) contribute to risky and impatient choices, especially in youth. However, valuation in ventral striatum supports reward-maximizing and gist strategies in adulthood. Indeed, processing becomes less "rational" in the sense of maximizing gains and more noncompensatory (eye movements indicate fewer tradeoffs) as development progresses from adolescence to adulthood, as predicted. Implications for theoretically predicted "public-health paradoxes" are discussed, including gist versus verbatim thinking in drug experimentation and addiction.

Neural Response to Social Exclusion Moderates the Link Between Adolescent Anxiety Symptoms and Substance Use

BACKGROUND

Substance use (SU) typically increases from middle to late adolescence. Anxiety is one factor associated with greater SU, although variability in who uses substances remains. Some models suggest that brain-based susceptibility markers could reveal which adolescents are at a higher risk for psychopathology, but it is unknown whether these individual differences attenuate or accentuate the association between anxiety and elevated SU even if normative. This study addressed this gap by testing whether neural response to social exclusion moderates the association between anxiety symptoms and increased SU from middle to late adolescence.

METHODS

Participants were 181 Mexican-origin adolescents (48% female; 16-17 years old) who completed a social exclusion task during a functional magnetic resonance imaging scan and filled out questionnaires about their SU and anxiety symptoms. Analyses focused on neural response to social exclusion versus inclusion within 3 regions of interest and change in SU across 2 years.

RESULTS

Dorsal anterior cingulate cortex response to social exclusion, but not subgenual anterior cingulate cortex or anterior insula, moderated the relation between anxiety symptoms and SU, such that higher anxiety symptoms predicted a greater relative increase in SU only for those youth with a lower dorsal anterior cingulate cortex response to exclusion.

CONCLUSIONS

Blunted dorsal anterior cingulate cortex response to social exclusion may serve as a neural susceptibility marker of altered conflict monitoring or emotion regulation in middle adolescence that, in combination with high levels of anxious feelings, elevates the risk for onset of and/or increased SU by late adolescence. These findings have implications for designing targeted interventions to mitigate SU among adolescents.

Myelin development in cerebral gray and white matter during adolescence and late childhood

Myelin development during adolescence is becoming an area of growing interest in view of its potential relationship to cognition, behavior, and learning. While recent investigations suggest that both white matter (WM) and gray matter (GM) undergo protracted myelination during adolescence, quantitative relations between myelin development in WM and GM have not been previously studied. We quantitatively characterized the dependence of cortical GM, WM, and subcortical myelin density across the brain on age, gender, and puberty status during adolescence with the use of a novel macromolecular proton fraction (MPF) mapping method. Whole-brain MPF maps from a cross-sectional sample of 146 adolescents (age range 9–17 years) were collected. Myelin density was calculated from MPF values in GM and WM of all brain lobes, as well as in subcortical structures. In general, myelination of cortical GM was widespread and more significantly correlated with age than that of WM. Myelination of GM in the parietal lobe was found to have a significantly stronger age dependence than that of GM in the frontal, occipital, temporal and insular lobes. Myelination of WM in the temporal lobe had the strongest association with age as compared to WM in other lobes. Myelin density was found to be higher in males as compared to females when averaged across all cortical lobes, as well as in a bilateral subcortical region. Puberty stage was significantly correlated with myelin density in several cortical areas and in the subcortical GM. These findings point to significant differences in the trajectories of myelination of GM and WM across brain regions and suggest that cortical GM myelination plays a dominant role during adolescent development.

Cognitive and Emotional Empathy in Young Adolescents: an fMRI Study

Objectives

We investigated the differences in cognitive and emotional empathic ability between adolescents and adults, and the differences of the brain activation during cognitive and emotional empathy tasks.

Methods

Adolescents (aged 13–15 years, n=14) and adults (aged 19–29 years, n=17) completed a range of empathic ability questionnaires and were scanned functional magnetic resonance imaging (fMRI) during both cognitive and emotional empathy task. Differences in empathic ability and brain activation between the groups were analyzed.

Results

Both cognitive and emotional empathic ability were significantly lower in the adolescent compared to the adult group. Comparing the adolescent to the adult group showed that brain activation was significantly greater in the right transverse temporal gyrus (BA 41), right insula (BA 13), right superior parietal lobule (BA 7), right precentral gyrus (BA 4), and right thalamus whilst performing emotional empathy tasks. No brain regions showed significantly greater activation in the adolescent compared to the adult group while performing cognitive empathy task. In the adolescent group, scores of the Fantasy Subscale in the Interpersonal Reactivity Index, which reflects cognitive empathic ability, negatively correlated with activity of right superior parietal lobule during emotional empathic situations (r=-0.739, p=0.006).

Conclusion

These results strongly suggest that adolescents possess lower cognitive and emotional empathic abilities than adults do and require compensatory hyperactivation of the brain regions associated with emotional empathy or embodiment in emotional empathic situation. Compensatory hyperactivation in the emotional empathy-related brain areas among adolescents are likely associated with their lower cognitive empathic ability.

Δ9-Tetrahydrocannabinol changes the brain lipidome and transcriptome differentially in the adolescent and the adult

Exposing the adolescent brain to drugs of abuse is associated with increased risk for adult onset psychopathologies. Cannabis use peaks during adolescence, with largely unknown effects on the developing brain. Cannabis' major psychoactive component, Δ9-tetrahydrocannabinol (THC) alters neuronal, astrocytic, and microglial signaling. Therefore, multiple cellular and signaling pathways are affected with a single dose of THC. The endogenous cannabinoids (eCBs), N-arachidonoyl ethanolamine (AEA) and 2-arachidonoyl glycerol (2-AG) are members of an interconnected lipidome that includes an emerging class of AEA structural analogs, the lipoamines, additional 2-acyl glycerols, free fatty acids, and prostaglandins (PGs). Lipids in this lipidome share many biosynthetic and metabolic pathways, yet have diverse signaling properties. Here, we show that acute THC drives age-dependent changes in this lipidome across 8 regions of the female mouse brain. Interestingly, most changes are observed in the adult, with eCBs and related lipids predominately decreasing. Analysis of THC and metabolites reveals an unequal distribution across these brain areas; however, the highest levels of THC were measured in the hippocampus (HIPP) in all age groups. Transcriptomic analysis of the HIPP after acute THC showed that like the lipidome, the adult transcriptome demonstrated significantly more changes than the adolescent. Importantly, the regulation of 31 genes overlapped between the adolescent and the adult, suggesting a conserved transcriptomic response in the HIPP to THC exposure independent of age. Taken together these data illustrate that the first exposure to a single dose of THC has profound effects on signaling in the CNS.

Emotion regulation in adolescents: An ERP study

AIMS

The use of emotion regulation strategies can reduce the intensity of negative emotional experiences. Event related potentials (ERPs), specifically the late positive potential (LPP), are known to be sensitive to this modulation in adults. This is the first study to explore the neural correlates of expressive suppression in adolescents. We sought to replicate previous findings from emotion regulation studies with adult populations, show that the LPP can be modulated by expressive suppression in healthy adolescents, and examine the influence of age on LPP changes.

METHOD

ERPs of 53 healthy adolescents (12-17 years old) performing an emotion regulation task (expressive suppression) were recorded.

RESULTS

Expressive suppression altered the LPP in adolescents with both increases and decreases noted depending on time window and recording site. The LPP during expressive suppression was decreased with increasing age.

CONCLUSIONS

The findings suggest that 1) the LPP is an effective tool to study processes associated with emotion regulation in adolescents, and 2) expressive suppression, in terms of its neural indicators, seems to become more effective with age. The nature and utility of expressive suppression as a specific form of emotion regulation in adolescents are discussed.