Bipolar Disorder is costly and debilitating, and many treatments have side effects. Transcranial Direct Current Stimulation (tDCS) is a well-tolerated neuromodulation technique that may be a useful ...treatment for Bipolar Disorder if targeted to neural regions implicated in the disorder. One potential region is the left ventrolateral prefrontal cortex (vlPFC), which shows abnormally elevated activity during reward expectancy in individuals with Bipolar Disorder. We used a counterbalanced repeated measures design to assess the impact of cathodal (inhibitory) tDCS over the left vlPFC on reward circuitry activity, functional connectivity, and affect in adults with Bipolar Disorder, as a step toward developing novel interventions for individuals with the disorder. -1mA cathodal tDCS was administered over the left vlPFC versus a control region, left somatosensory cortex, concurrently with neuroimaging. Affect was assessed pre and post scan in remitted Bipolar Disorder (n = 27) and age/gender-matched healthy (n = 31) adults. Relative to cathodal tDCS over the left somatosensory cortex, cathodal tDCS over the left vlPFC lowered reward expectancy-related left ventral striatal activity (F(1,51) = 9.61, p = 0.003), and was associated with lower negative affect post scan, controlling for pre-scan negative affect, (F(1,49) = 5.57, p = 0.02) in all participants. Acute cathodal tDCS over the left vlPFC relative to the left somatosensory cortex reduces reward expectancy-related activity and negative affect post tDCS. Build on these findings, future studies can determine whether chronic cathodal tDCS over the left vlPFC has sustained effects on mood in individuals with Bipolar Disorder, to guide new treatment developments for the disorder.
The genus Ambrosiella accommodates species of Ceratocystidaceae (Microascales) that are obligate, mutualistic symbionts of ambrosia beetles, but the genus appears to be polyphyletic and more diverse ...than previously recognized. In addition to Ambrosiella xylebori, Ambrosiella hartigii, Ambrosiella beaveri, and Ambrosiella roeperi, three new species of Ambrosiella are described from the ambrosia beetle tribe Xyleborini: Ambrosiella nakashimae sp. nov. from Xylosandrus amputatus, Ambrosiella batrae sp. nov. from Anisandrus sayi, and Ambrosiella grosmanniae sp. nov. from Xylosandrus germanus. The genus Meredithiella gen. nov. is created for symbionts of the tribe Corthylini, based on Meredithiella norrisii sp. nov. from Corthylus punctatissimus. The genus Phialophoropsis is resurrected to accommodate associates of the Xyloterini, including Phialophoropsis trypodendri from Trypodendron scabricollis and Phialophoropsis ferruginea comb. nov. from Trypodendron lineatum. Each of the ten named species was distinguished by ITS rDNA barcoding and morphology, and the ITS rDNA sequences of four other putative species were obtained with Ceratocystidaceae-specific primers and template DNA extracted from beetles or galleries. These results support the hypothesis that each ambrosia beetle species with large, complex mycangia carries its own fungal symbiont. Conidiophore morphology and phylogenetic analyses using 18S (SSU) rDNA and TEF1α DNA sequences suggest that these three fungal genera within the Ceratocystidaceae independently adapted to symbiosis with the three respective beetle tribes. In turn, the beetle genera with large, complex mycangia appear to have evolved from other genera in their respective tribes that have smaller, less selective mycangia and are associated with Raffaelea spp. (Ophiostomatales).
Abstract
We report the results of our follow-up campaign for the neutron-star—black-hole (NSBH) merger GW200115 detected during the O3 run of the Advanced LIGO and Advanced Virgo detectors. We ...obtained wide-field observations with the Deca-Degree Optical Transient Imager covering ∼20% of the total probability area down to a limiting magnitude of
w
= 20.5 AB at ∼23 hr after the merger. Our search for counterparts returns a single candidate (AT2020aeo), likely not associated with the merger. In total, only 25 sources of interest were identified by the community and later discarded as unrelated to the GW event. We compare our upper limits with the emission predicted by state-of-the-art kilonova simulations and disfavor high-mass ejecta (>0.1
M
⊙
), indicating that the spin of the system is not particularly high. By combining our optical limits with gamma-ray constraints from Swift and Fermi, we disfavor the presence of a standard short-duration burst for viewing angles ≲15° from the jet axis. Our conclusions are, however, limited by the large localization region of this GW event, and accurate prompt positions remain crucial to improving the efficiency of follow-up efforts.
Altered corticostriatothalamic encoding of reinforcement is a core feature of depression. Here we examine reinforcement learning in late-life depression in the theoretical framework of the vascular ...depression hypothesis. This hypothesis attributes the co-occurrence of late-life depression and poor executive control to prefrontal/cingulate disconnection by vascular lesions.
Our fMRI study compared 31 patients aged ⩾60 years with major depression to 16 controls. Using a computational model, we estimated neural and behavioral responses to reinforcement in an uncertain, changing environment (probabilistic reversal learning).
Poor executive control and depression each explained distinct variance in corticostriatothalamic response to unexpected rewards. Depression, but not poor executive control, predicted disrupted functional connectivity between the striatum and prefrontal cortex. White-matter hyperintensities predicted diminished corticostriatothalamic responses to reinforcement, but did not mediate effects of depression or executive control. In two independent samples, poor executive control predicted a failure to persist with rewarded actions, an effect distinct from depressive oversensitivity to punishment. The findings were unchanged in a subsample of participants with vascular disease. Results were robust to effects of confounders including psychiatric comorbidities, physical illness, depressive severity, and psychotropic exposure.
Contrary to the predictions of the vascular depression hypothesis, altered encoding of rewards in late-life depression is dissociable from impaired contingency learning associated with poor executive control. Functional connectivity and behavioral analyses point to a disruption of ascending mesostriatocortical reward signals in late-life depression and a failure of cortical contingency encoding in elderly with poor executive control.
Identification of neural markers associated with risk for manic symptoms is an important challenge for neuropsychiatric research. Previous work has highlighted the association between predisposition ...for mania/hypomania and elevated reward sensitivity. Elevated activity in the left ventrolateral prefrontal cortex (L vlPFC) during reward expectancy (RE) is associated with measures predictive of risk for manic/hypomanic symptoms. However, no studies have examined this relationship longitudinally. The goal of this study was to identify a neural marker associated with longitudinal risk for manic/hypomanic symptoms.
We used a card guessing functional magnetic resonance imaging (fMRI) paradigm to examine RE-related L vlPFC activity. One hundred and three young adults who were either healthy or experiencing psychological distress completed a single baseline fMRI scan and self-report measures of manic/hypomanic symptoms. Self-report measures were repeated up to two follow up visits over one year.
We identified a significant positive relationship between baseline RE-related L vlPFC activity and MOODS Manic Domain scores up to one-year post scan. This relationship was specific to manic symptoms and was not present for MOODS depression-related domains.
This study was not designed to predict conversion to bipolar disorder, but rather the more proximal construct of lifetime risk for mania/hypomania.
RE-related L vlPFC activity may serve as an important marker of risk for future manic/hypomanic symptoms and may also be a potential target for intervention.
•Left ventrolateral PFC activity to reward expectancy correlates with mania risk over time•This relationship is not present for depressive or other mood symptoms•Left ventrolateral PFC activity to RE is a promising marker of future mania risk
ABSTRACT
We report on our observing campaign of the compact binary merger GW190814, detected by the Advanced LIGO and Advanced Virgo detectors on 2019 August 14. This signal has the best localization ...of any observed gravitational wave (GW) source, with a 90 per cent probability area of 18.5 deg2, and an estimated distance of ≈240 Mpc. We obtained wide-field observations with the Deca-Degree Optical Transient Imager (DDOTI) covering 88 per cent of the probability area down to a limiting magnitude of w = 19.9 AB. Nearby galaxies within the high probability region were targeted with the Lowell Discovery Telescope (LDT), whereas promising candidate counterparts were characterized through multicolour photometry with the Reionization and Transients InfraRed (RATIR) and spectroscopy with the Gran Telescopio de Canarias (GTC). We use our optical and near-infrared limits in conjunction with the upper limits obtained by the community to constrain the possible electromagnetic counterparts associated with the merger. A gamma-ray burst seen along its jet’s axis is disfavoured by the multiwavelength data set, whereas the presence of a burst seen at larger viewing angles is not well constrained. Although our observations are not sensitive to a kilonova similar to AT2017gfo, we can rule out high-mass (>0.1 M⊙) fast-moving (mean velocity ≥0.3c) wind ejecta for a possible kilonova associated with this merger.
The relationships between sexual trauma, cognitive appraisals, and subtypes of sexual intrusive thoughts have not been adequately examined in the context of obsessive–compulsive concerns. We employed ...variations of a moderated mediation model to test these relationships, situating sexual trauma as the predictor, sexual intrusive thoughts as the outcome, cognitive appraisals of these thoughts as the mediator, and subtypes of sexual intrusive thoughts as the moderator of the predictor–mediator link. Based on the continuum perspective, 180 individuals (159 females, 21 males) with or without a history of sexual trauma were recruited to complete measures assessing their most distressing sexual intrusion, cognitive appraisals, and severity of sexual intrusive thoughts. The results indicated that individuals with a history of sexual trauma reported more intrusions with sexual harm content, greater distress with sexual intrusions, more dysfunctional appraisals, and more severe sexual intrusions. The trauma–sexual intrusions link was also separately mediated by responsibility and importance/control appraisals (and when combined), with medium-to-large effect sizes, although this model was not moderated by whether intrusions contained sexual harm content or not. These findings shed light on the posttraumatic effects of sexual violence on sexual intrusions, their appraisals, and level of distress and functional impairment associated with sexual intrusive thoughts, with key clinical and research implications.
Dopamine has long been implicated in reward‐based learning and the expression of such learned associations on performance. Robust evidence supports its effects on learning and performance, but ...teasing these apart has proved challenging. Here we have adapted a classic test of value‐based learning, the probabilistic selection task, to disentangle effects of dopamine on value‐based performance from effects on value‐based learning. Valence‐specific effects of dopamine on this specific task cannot be accounted for by modulation of learning, and therefore must reflect modulation of performance. We found that dopaminergic medication, consisting of levodopa and/or dopamine agonists taken at own dose, in 18 patients with mild Parkinson’s disease (Hoehn and Yahr < 2.5) potentiated reward‐based approach in terms of both accuracy and reaction times, while leaving punishment‐based avoidance unaffected. These data demonstrate that the effects of dopamine on probabilistic action selection are at least partly mediated by effects on the expression of learned associations rather than on learning itself, and help refine current models of dopamine’s role in reward.
Dopamine has long been implicated in the acquisition of stimulus‐response associations, but its effect on the expression of value‐based representations is unclear. These data highlight a role for dopamine in reward‐driven behavioral control beyond that already established in learning and plasticity.
Ambrosia beetles farm fungal cultivars (ambrosia fungi) and carry propagules of the fungal mutualists in storage organs called mycangia, which occur in various body parts and vary greatly in size and ...complexity. The evolution of ambrosia fungi is closely tied to the evolution and development of the mycangia that carry them. The understudied ambrosia beetle tribe Xyloterini included lineages with uncharacterized ambrosia fungi and mycangia, which presented an opportunity to test whether developments of different mycangium types in a single ambrosia beetle lineage correspond with concomitant diversity in their fungal mutualists. We collected representatives of all three Xyloterini genera (Trypodendron, Indocryphalus, and Xyloterinus politus) and characterized their ambrosia fungi in pure culture and by DNA sequencing. The prothoracic mycangia of seven Trypodendron species all yielded Phialophoropsis (Microascales) ambrosia fungi, including three new species, although these relationships were not all species specific. Indocryphalus mycangia are characterized for the first time in the Asian I. pubipennis. They comprise triangular prothoracic cavities substantially smaller than those of Trypodendron and unexpectedly carry an undescribed species of Toshionella (Microascales), which are otherwise ambrosia fungi of Asian Scolytoplatypus (Scolytoplatypodini). Xyloterinus politus has two different mycangia, each with a different ambrosia fungus: Raffaelea cf. canadensis RNC5 (Ophiostomatales) in oral mycangia of both sexes and Kaarikia abrahamsonii (Sordariomycetes, genus incertae sedis with affinity for Distoseptisporaceae), a new genus and species unrelated to other known ambrosia fungi, in shallow prothoracic mycangia of females. In addition to their highly adapted mycangial mutualists, Trypodendron and X. politus harbor a surprising diversity of facultative symbionts in their galleries, including Raffaelea. A diversity of ambrosia fungi and mycangia suggest multiple ancestral cultivar captures or switches in the history of tribe Xyloterini, each associated with unique adaptations in mycangium anatomy. This further supports the theory that developments of novel mycangium types are critical events in the evolution of ambrosia beetles and their coadapted fungal mutualists.
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