We recall the experimental approaches involved in the discovery of hydrogen bonds in deoxyribonucleic acid (DNA) made 70 years ago by a team of scientists at University College Nottingham led by J.M. ...Gulland, and in relation to previous studies. This discovery proved an important step in the elucidation of the correct structure for DNA made by J.D. Watson and F.H.C. Crick, as acknowledged in '
'. At that time of the discovery, however, it was impossible to delineate between inter- and intra-chain hydrogen bonds. We also consider in the light of more recent hydrodynamic theory a tentative model for DNA proposed by Gulland's and D.O. Jordan's PhD student J.M. Creeth in his PhD thesis of 1948, with the correct prediction of two chains with a sugar-phosphate backbone on the exterior and hydrogen-bonded bases between the nucleotide bases of opposite chains in the interior. Our analysis shows that his incorporation of alternating breaks in the two-chain structure was not necessary to explain the viscosity data on scission of hydrogen bonds after titrating to high or low pH. Although Creeth's model is a depiction of DNA structure alone, he could not know whether the hydrogen bonding was intermolecular, although this was subsequently proved correct by others. The mechanisms by which replicative processes occurred were of course unknown at that time, and so, he could not have realised how closely his tentative model resembled steps in some viral replicative mechanisms involving the molecule of life that he was working on.
Changes in reward-related behavior are an important component of normal adolescent affective development. Understanding the neural underpinnings of these normative changes creates a foundation for ...investigating adolescence as a period of vulnerability to affective disorders, substance use disorders, and health problems. Studies of reward-related brain function have revealed conflicting findings regarding developmental change in the reactivity of the striatum and medial prefrontal cortex (mPFC) and have not considered puberty. The current study focused on puberty-specific changes in brain function and their association with mood.
A sample of 77 healthy adolescents (26 pre-/early pubertal, 51 mid-/late pubertal) recruited in a narrow age range (mean = 11.94 years, SD = 0.75) were assessed for sexual maturation and circulating testosterone, completed a functional magnetic resonance imaging (fMRI) guessing task with monetary reward, and underwent experience sampling of mood in natural environments. For comparison, 19 healthy adults completed the fMRI assessment.
Adolescents with more advanced pubertal maturation exhibited less striatal and more mPFC reactivity during reward outcome than similarly aged adolescents with less advanced maturation. Testosterone was positively correlated with striatal reactivity in boys during reward anticipation and negatively correlated with striatal reactivity in girls and boys during reward outcome. Striatal reactivity was positively correlated with real-world subjective positive affect and negatively correlated with depressive symptoms. mPFC reactivity was positively correlated with depressive symptoms.
Reward-related brain function changes with puberty and is associated with adolescents' positive affect and depressive symptoms. Increased reward-seeking behavior at this developmental point could serve to compensate for these changes.
Previous studies, predominantly in experimental animals, have suggested the presence of a differentiation of function across the hippocampal formation. In rodents, ventral regions are thought to be ...involved in emotional behavior while dorsal regions mediate cognitive or spatial processes. Using a combination of modeling the co-occurrence of significant activations across thousands of neuroimaging experiments and subsequent data-driven clustering of these data we were able to provide evidence of distinct subregions within a region corresponding to the human subiculum, a critical hub within the hippocampal formation. This connectivity-based model consists of a bilateral anterior region, as well as separate posterior and intermediate regions on each hemisphere. Functional connectivity assessed both by meta-analytic and resting fMRI approaches revealed that more anterior regions were more strongly connected to the default mode network, and more posterior regions were more strongly connected to ‘task positive’ regions. In addition, our analysis revealed that the anterior subregion was functionally connected to the ventral striatum, midbrain and amygdala, a circuit that is central to models of stress and motivated behavior. Analysis of a behavioral taxonomy provided evidence for a role for each subregion in mnemonic processing, as well as implication of the anterior subregion in emotional and visual processing and the right posterior subregion in reward processing. These findings lend support to models which posit anterior–posterior differentiation of function within the human hippocampal formation and complement other early steps toward a comparative (cross-species) model of the region.
•Data driven parcellation of the subiculum reveals five clusters.•Anterior regions were better connected to default mode network.•Region plays a role in memory, visual cognition and emotion.
Abstract Recent evidence indicates that the propensity towards experiencing disgust may contribute to the development and maintenance of some anxiety disorders. This article summarizes the empirical ...evidence with emphasis on illuminating potential mediators, moderators, and mechanisms of the disgust–anxiety disorder association that may inform the development of an integrative conceptual model. Early research using neuroimaging methods suggest that disgust processing is associated with activation of the insula. This research has the potential to facilitate progress in developing an empirically informed psychobiological theory on the causal role of disgust in the anxiety disorders.
•The differences in DLPFC activation in depressed individuals vs. healthy controls during recognition of emotional and neutral facial expressions was examined using functional near-infrared ...spectroscopy.•Depressed individuals, compared to healthy controls, were slower and less accurate in recognizing neutral, but not happy or fearful, facial emotional expressions.•Depressed individuals, but not healthy controls, rely on functioning of the right DLPFC during recognition of neutral and happy facial expressions.•Depressed individuals who had lower activation in the right DLPFC during recognition of neutral facial expression also had lower recognition accuracy for neutral facial expressions compared to depressed individuals who had greater right DLPFC activation.
Depressed individuals often perceive neutral facial expressions as emotional. Neurobiological underpinnings of this effect remain unclear. We investigated the differences in prefrontal cortical (PFC) activation in depressed individuals vs. healthy controls (HC) during recognition of emotional and neutral facial expressions using functional near infrared spectroscopy (fNIRS).
In Experiment 1, 33 depressed individuals and 20 HC performed the Emotion Intensity Rating task in which they rated intensity of facial emotional expressions. In Experiment 2, a different set of participants (18 depressed individuals and 16 HC) performed the same task while their PFC activation was measured using fNIRS.
Both experiments showed that depressed individuals were slower and less accurate in recognizing neutral, but not happy or fearful, facial emotional expressions. Experiment 2 revealed that lower accuracy for neutral facial emotional expressions was associated with lower right PFC activation in depressed individuals, but not HC. In addition, depressed individuals, compared to HC, had lower right PFC activation during recognition of happy facial expressions.
Relatively small sample size
Recognition of neutral facial expressions is impaired in depressed individuals. Greater impairment corresponds to lower right PFC activation during neutral face processing. Recognition of happy facial expressions is comparable for depressed individuals and HC, but the former have significantly lower right PFC activation. Taken together, these findings suggest that the ability of depressed individuals to discriminate neutral and emotional signals in the environment may be affected by aberrant functioning of right PFC.
Background
Adult posttraumatic stress disorder (PTSD) has been characterized by altered fear‐network connectivity. Childhood trauma is a major risk factor for adult PTSD, yet its contribution to ...fear‐network connectivity in PTSD remains unexplored. We examined, within a single model, the contribution of childhood maltreatment, combat exposure, and combat‐related posttraumatic stress symptoms (PTSS) to resting‐state connectivity (rs‐FC) of the amygdala and hippocampus in military veterans.
Methods
Medication‐free male veterans (n = 27, average 26.6 years) with a range of PTSS completed resting‐state fMRI. Measures including the Clinician‐Administered PTSD Scale (CAPS), Childhood Trauma Questionnaire (CTQ), and Combat Exposure Scale (CES) were used to predict rs‐FC using multilinear regression. Fear‐network seeds included the amygdala and hippocampus.
Results
Amygdala: CTQ predicted lower connectivity to ventromedial prefrontal cortex (vmPFC), but greater anticorrelation with dorsal/lateral PFC. CAPS positively predicted connectivity to insula, and loss of anticorrelation with dorsomedial/dorsolateral (dm/dl)PFC. Hippocampus: CTQ predicted lower connectivity to vmPFC, but greater anticorrelation with dm/dlPFC. CES predicted greater anticorrelation, whereas CAPS predicted less anticorrelation with dmPFC.
Conclusions
Childhood trauma, combat exposure, and PTSS differentially predict fear‐network rs‐FC. Childhood maltreatment may weaken ventral prefrontal–subcortical circuitry important in automatic fear regulation, but, in a compensatory manner, may also strengthen dorsal prefrontal–subcortical pathways involved in more effortful emotion regulation. PTSD symptoms, in turn, appear to emerge with the loss of connectivity in the latter pathway. These findings suggest potential mechanisms by which developmental trauma exposure leads to adult PTSD, and which brain mechanisms are associated with the emergence of PTSD symptoms.
Individual differences in personality traits affect the quality of social relationships. The parent-child relationship is among the most impactful social relationships in an individual's life, and ...positive parenting behaviors are known to support positive child development. The present study aimed to identify personality predictors-measured prior to conception at age 16-on later positive parenting behaviors. Young women (n = 207; 83.5% Black or multiracial; 86.9% receiving public assistance) who were followed since childhood as part of a prospective longitudinal study were observed interacting with their infants 4 months postpartum. We tested prospective associations between personality factors relevant to the quality and maintenance of social relationships-empathy, callousness, and rejection sensitivity-and coded dimensions of parenting behavior: maternal warmth, responsiveness, and mental state talk. We additionally examined potential moderating effects of infant affect on the relations between personality and parenting behavior. Results indicated that preconception empathy predicted later maternal warmth and responsivity, whereas preconception callousness was inversely associated with maternal warmth. The association between rejection sensitivity and maternal mental state talk was moderated by infant affect, consistent with a "goodness-of-fit" framework. The present study is the first to our knowledge to report associations between preconception personality and later parenting behaviors. The findings suggest that a woman's personality traits in adolescence, potentially years before she becomes a mother, can predict her behavior during interactions with her infant. Clinically, findings suggest the potential for interventions in adolescence to influence later parenting behavior and ultimately impact children's developmental outcomes.
Functional Magnetic Resonance Imagine (fMRI) is an important assessment tool in longitudinal studies of mental illness and its treatment. Understanding the psychometric properties of fMRI-based ...metrics, and the factors that influence them, will be critical for properly interpreting the results of these efforts. The current study examined whether the choice among alternative model specifications affects estimates of test-retest reliability in key emotion processing regions across a 6-month interval. Subjects (N = 46) performed an emotional-faces paradigm during fMRI in which neutral faces dynamically morphed into one of four emotional faces. Median voxelwise intraclass correlation coefficients (mvICCs) were calculated to examine stability over time in regions showing task-related activity as well as in bilateral amygdala. Four modeling choices were evaluated: a default model that used the canonical hemodynamic response function (HRF), a flexible HRF model that included additional basis functions, a modified CompCor (mCompCor) model that added corrections for physiological noise in the global signal, and a final model that combined the flexible HRF and mCompCor models. Model residuals were examined to determine the degree to which each pipeline met modeling assumptions. Results indicated that the choice of modeling approaches impacts both the degree to which model assumptions are met and estimates of test-retest reliability. ICC estimates in the visual cortex increased from poor (mvICC = 0.31) in the default pipeline to fair (mvICC = 0.45) in the full alternative pipeline - an increase of 45%. In nearly all tests, the models with the fewest assumption violations generated the highest ICC estimates. Implications for longitudinal treatment studies that utilize fMRI are discussed.
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