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Hemispheric asymmetry is a cardinal feature of human brain organization. Altered brain asymmetry has also been linked to some cognitive and neuropsychiatric disorders. Here, the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium presents the largest-ever analysis of cerebral cortical asymmetry and its variability across individuals. Cortical thickness and surface area were assessed in MRI scans of 17,141 healthy individuals from 99 datasets worldwide. Results revealed widespread asymmetries at both hemispheric and regional levels, with a generally thicker cortex but smaller surface area in the left hemisphere relative to the right. Regionally, asymmetries of cortical thickness and/or surface area were found in the inferior frontal gyrus, transverse temporal gyrus, parahippocampal gyrus, and entorhinal cortex. These regions are involved in lateralized functions, including language and visuospatial processing. In addition to population-level asymmetries, variability in brain asymmetry was related to sex, age, and intracranial volume. Interestingly, we did not find significant associations between asymmetries and handedness. Finally, with two independent pedigree datasets (n = 1,443 and 1,113, respectively), we found several asymmetries showing significant, replicable heritability. The structural asymmetries identified and their variabilities and heritability provide a reference resource for future studies on the genetic basis of brain asymmetry and altered laterality in cognitive, neurological, and psychiatric disorders.

In line with the Research Domain Criteria (RDoC) , we set out to investigate the brain basis of psychopathology within a transdiagnostic, dimensional framework. We performed an integrative structural-functional linked independent component analysis to study the relationship between brain measures and a broad set of biobehavioral measures in a sample (n = 295) with both mentally healthy participants and patients with diverse non-psychotic psychiatric disorders (i.e. mood, anxiety, addiction, and neurodevelopmental disorders). To get a more complete understanding of the underlying brain mechanisms, we used gray and white matter measures for brain structure and both resting-state and stress scans for brain function. The results emphasize the importance of the executive control network (ECN) during the functional scans for the understanding of transdiagnostic symptom dimensions. The connectivity between the ECN and the frontoparietal network in the aftermath of stress was correlated with symptom dimensions across both the cognitive and negative valence domains, and also with various other health-related biological and behavioral measures. Finally, we identified a multimodal component that was specifically associated with the diagnosis of autism spectrum disorder (ASD). The involvement of the default mode network, precentral gyrus, and thalamus across the different modalities of this component may reflect the broad functional domains that may be affected in ASD, like theory of mind, motor problems, and sensitivity to sensory stimuli, respectively. Taken together, the findings from our extensive, exploratory analyses emphasize the importance of a dimensional and more integrative approach for getting a better understanding of the brain basis of psychopathology.

[This corrects the article DOI: 10.1371/journal.pone.0260952.].

Acute stress shifts the brain into a state that fosters rapid defense mechanisms. Stress-related neuromodulators are thought to trigger this change by altering properties of large-scale neural populations throughout the brain. We investigated this brain-state shift in humans. During exposure to a fear-related acute stressor, responsiveness and interconnectivity within a network including cortical (frontoinsular, dorsal anterior cingulate, inferotemporal, and temporoparietal) and subcortical (amygdala, thalamus, hypothalamus, and midbrain) regions increased as a function of stress response magnitudes, β-adrenergic receptor blockade, but not cortisol synthesis inhibition, diminished this increase. Thus, our findings reveal that noradrenergic activation during acute stress results in prolonged coupling within a distributed network that integrates information exchange between regions involved in autonomic-neuroendocrine control and vigilant attentional reorienting.

Selective serotonin reuptake inhibitors (SSRIs) are considered safe and are frequently used during pregnancy. However, two case-control studies suggested an association between prenatal SSRI exposure with childhood autism. To prospectively determine whether intra-uterine SSSRI exposure is associated with childhood autistic symptoms in a population-based study. A total of 376 children prenatally exposed to maternal depressive symptoms (no SSRI exposure), 69 children prenatally exposed to SSRIs and 5531 unexposed children were included. Child pervasive developmental and affective problems were assessed by parental report with the Child Behavior Checklist at ages 1.5, 3 and 6. At age 6, we assessed autistic traits using the Social Responsiveness Scale (n = 4264). Prenatal exposure to maternal depressive symptoms without SSRIs was related to both pervasive developmental (odds ratio (OR) = 1.44, 95% CI 1.07-1.93) and affective problems (OR = 1.44, 95% CI 1.15-1.81). Compared with unexposed children, those prenatally exposed to SSRIs also were at higher risk for developing pervasive developmental problems (OR = 1.91, 95% CI 1.13-3.47), but not for affective problems. Children prenatally exposed to SSRIs also had more autistic traits (B = 0.15, 95% CI 0.08-0.22) compared with those exposed to depressive symptoms only. Our results suggest an association between prenatal SSRI exposure and autistic traits in children. Prenatal depressive symptoms without SSRI use were also associated with autistic traits, albeit this was weaker and less specific. Long-term drug safety trials are needed before evidence-based recommendations are possible.

Emotionally arousing experiences are typically well remembered not only due to immediate effects at encoding, but also through further strengthening of subsequent consolidation processes. A large body of research shows how neuromodulatory systems promote synaptic consolidation. However, how emotionally arousing experiences alter systems-level interactions, presumably a consequence of modifications at a synaptic level, remains unclear. Animal models predict that memory traces are maintained by spontaneous reactivations across hippocampal–neocortical circuits during “offline” periods such as post-learning rest, and suggest this might be stronger for emotional memories. The present study was designed to test this hypothesis in humans using functional Magnetic Resonance Imaging. Participants underwent a two-category localizer paradigm followed by a categorical differential delay fear conditioning paradigm interleaved with blocks of awake rest. Counterbalanced across participants, exemplars of one category (CS+), but not the other (CS−), were paired with mild electrical shocks. Fear recall (differential conditioned pupil dilation) was tested 24h later. Analyses of the localizer paradigm replicate earlier work showing category-specific response patterns in neocortical higher-order visual regions. Critically, we show that during post-learning rest, spontaneous reactivation of these neocortical patterns was stronger for the CS+ than the CS− category. Furthermore, hippocampal connectivity with the regions exhibiting these reactivations predicted strength of fear recall 24h later. We conclude that emotional arousal during learning promotes spontaneous post-learning reactivation of neocortical representations of recent experiences, which leads to better memory when coinciding with hippocampal connectivity. Our findings reveal a systems-level mechanism that may explain the persistence of long-term memory for emotional experiences. •Cortical representations of fear-conditioned stimuli are reactivated offline.•Hippocampal–neocortical connectivity predicts strength of fear recall 24h later.•This systems-level mechanism might explain the persistence of emotional memories.

The retention of episodic-like memory is enhanced, in humans and animals, when something novel happens shortly before or after encoding. Using an everyday memory task in mice, we sought the neurons mediating this dopamine-dependent novelty effect, previously thought to originate exclusively from the tyrosine-hydroxylase-expressing (TH + ) neurons in the ventral tegmental area. Here we report that neuronal firing in the locus coeruleus is especially sensitive to environmental novelty, locus coeruleus TH + neurons project more profusely than ventral tegmental area TH + neurons to the hippocampus, optogenetic activation of locus coeruleus TH + neurons mimics the novelty effect, and this novelty-associated memory enhancement is unaffected by ventral tegmental area inactivation. Surprisingly, two effects of locus coeruleus TH + photoactivation are sensitive to hippocampal D 1 /D 5 receptor blockade and resistant to adrenoceptor blockade: memory enhancement and long-lasting potentiation of synaptic transmission in CA1 ex vivo . Thus, locus coeruleus TH + neurons can mediate post-encoding memory enhancement in a manner consistent with possible co-release of dopamine in the hippocampus. Projections from the locus coeruleus, an area typically defined by noradrenergic signalling, to the hippocampus drive novelty-based memory enhancement through possible co-release of dopamine. Memory consolidation in the locus coeruleus Memory retention can be enhanced when something novel or categorically relevant occurs shortly before or after the time of memory encoding, as in 'flashbulb memory'. Dopamine-based mechanisms originating in the ventral tegmental area have been implicated in the phenomenon. These authors suggest that projections from the locus coeruleus—typically defined by noradrenergic signalling—to the hippocampus drive this novelty-based memory enhancement through the possible local release of dopamine.

Motivation can be generated intrinsically or extrinsically, and both kinds of motivation show similar facilitatory effects on memory. However, effects of extrinsic and intrinsic motivation on memory formation have not been studied in combination and thus, it is unknown whether they interact and how such interplay is neurally implemented. In the present study, both extrinsic monetary reward and intrinsic curiosity enhanced memory performance, without evidence for an interaction. Functional magnetic resonance imaging revealed that curiosity-driven activity in the ventral striatal reward network appears to work cooperatively with the fronto-parietal attention network, while enhancing memory formation. In contrast, the monetary reward-modulated subsequent memory effect revealed deactivation in parietal midline regions. Thus, curiosity might enhance memory performance by allocation of attentional resources and reward-related processes; while, monetary reward does so by suppression of task-irrelevant processing.