Sequential learning and rule abstraction in Bengalese finches

The Bengalese finch (Lonchura striata var. domestica) is a species of songbird. Males sing courtship songs with complex note-to-note transition rules, while females discriminate these songs when choosing their mate. The present study uses serial reaction time (RT) to examine the characteristics of the Bengalese finches’ sequential behaviours beyond song production. The birds were trained to produce the sequence with an “A–B–A” structure. After the RT to each key position was determined to be stable, we tested the acquisition of the trained sequential response by presenting novel and random three-term sequences (random test). We also examined whether they could abstract the embedded rule in the trained sequence and apply it to the novel test sequence (abstract test). Additionally, we examined rule abstraction through example training by increasing the number of examples in baseline training from 1 to 5. When considered as (gender) groups, training with 5 examples resulted in no statistically significant differences in the abstract tests, while statistically significant differences were observed in the random tests, suggesting that the male birds learned the trained sequences and transferred the abstract structure they had learned during the training trials. Individual data indicated that males, as opposed to females, were likely to learn the motor pattern of the sequence. The results are consistent with observations that males learn to produce songs with complex sequential rules, whereas females do not

Implications of the mild gas motion found with Hitomi in the core of the Perseus cluster

Based mainly on X-ray observations, studies are made on interactions between the intra-cluster medium (ICM) in clusters of galaxies and their member galaxies. Through (magneto)hydrodynamic and gravitational channels, the moving galaxies are expected to drag the ICM around them, and transfer to the ICM some fraction of their dynamical energies on cosmological time scales. This hypothesis is in line with several observations, including the possible cosmological infall of galaxies towards the cluster center, found over redshifts of z~1 to z~0. Further assuming that the energy lost by the galaxies is first converted into ICM turbulence and then dissipated, this picture can explain the subsonic and uniform ICM turbulence, measured with Hitomi in the core region of the Perseus cluster. The scenario may also explain several other unanswered problems regarding clusters of galaxies, including what prevents the ICM from the expected radiative cooling, how the various mass components in nearby clusters have attained different radial distributions, and how a thermal stability is realized between hot and cool ICM components that co-exist around cD galaxies. This view is also considered to pertain to the general scenario of galaxy evolution, including their environmental effects.Comment: 15 pages, 3 figures, accepted for publication in A&

Galaxy Infall by Interacting with its Environment: a Comprehensive Study of 340 Galaxy Clusters

To study systematically the evolution on the angular extents of the galaxy, ICM, and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts $<0.5$, based on all the available data with the Sloan Digital Sky Survey (SDSS) and {\it Chandra}/{\it XMM-Newton}. For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, were derived from a spatially-resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxy number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply towards outside in lower redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies travelling interior of the cluster have continuously fallen towards the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of $10^{44-45}$ erg $\rm s^{-1}$ per cluster from the member galaxies to their environment, which is expected to continue over cosmological time scales.Comment: 55 pages, 22 figures, accepted for publication in Astrophysical Journa

A Distinct Role of the Queen in Coordinated Workload and Soil Distribution in Eusocial Naked Mole-Rats

We investigated how group members achieve collective decision-making, by considering individual intrinsic behavioural rules and behavioural mechanisms for maintaining social integration. Using a simulated burrow environment, we investigated the behavioural rules of coordinated workload for soil distribution in a eusocial mammal, the naked mole-rat (Heterocephalus glaber). We tested two predictions regarding a distinct role of the queen, a socially dominant individual in the caste system: the presence of a queen would increase the workload of other caste individuals, and the cues by a queen would affect the soil distribution. In experiment 1, we placed four individuals of various castes from the same colony into an experimental burrow. Workers exhibited the highest frequency of workload compared to other castes. The presence of a queen activated the workload by other individuals. Individuals showed a consistent workload in a particular direction so as to bias the soil distribution. These results suggest that individuals have a consensus on soil distribution and that the queen plays a distinct role. In experiment 2, we placed the odour of a queen in one of four cells and observed its effect on other individuals’ workload and soil distribution. Relative to other cells, individuals frequently dug in the queen cell so the amount of soil in the queen cell decreased. These results suggest that queen odour is an important cue in coordinated workload and soil distribution in this species

Prescribing Pattern of Hypnotic Medications in Patients Initiating Treatment at Japanese Hospitals: A Nationwide, Retrospective, Longitudinal, Observational Study Using a Claims Database

Background Prolonged treatment of insomnia using benzodiazepine (BZD) receptor agonists, including BZD and non-BZD hypnotic drugs, can cause drug dependence, tolerance, abuse and other adverse events. These side effects are more common and/or severe in older adults taking different hypnotic drugs concomitantly. Therefore, a single prescription is limited to 30 daily doses for most BZD receptor agonists and restrictions apply to the prescription of more than three types of hypnotic drugs in Japan. Little is known, however, about the real-world prescribing pattern of hypnotic drugs in Japan. Objective We analysed prescribing patterns for hypnotic drugs in Japan to evaluate whether real-world use differs from guideline recommendations. Methods In this nationwide, retrospective, longitudinal, observational study, we analysed the types of hypnotic drugs prescribed, duration of medication and treatment setting in a subset of hospitals in Japan using a hospital-based administrative claims database (Medical Data Vision). Patients initiating treatment with hypnotic drugs between January 2012 and December 2016 were included in the analyses to assess the duration of medication and occurrence of co-prescription of a second and third hypnotic drug, within a year from prescription of the first hypnotic drugs. Results In 261,167 patients analysed, the first hypnotic drugs prescribed were BZDs (59.7%), non-BZDs (36.8%), a melatonin receptor agonist [MRA] (3.1%) and an orexin receptor antagonist [ORA] (0.4%). Benzodiazepine and non-BZD hypnotic drugs were mostly prescribed in inpatient settings (57.7% and 63.0%, respectively) and the MRA and ORA mostly in outpatient settings (62.6% and 65.4%, respectively). The departments that prescribed the most patients their first hypnotic drugs were internal medicine (23.6%), general surgery (11.8%), orthopaedic surgery (11.4%) and urology (5.3%). Of the total prescriptions of MRA and ORA as the first hypnotic drugs, 22.0% and 31.8% were in internal medicine, 4.4% each in general surgery, 6.0% and 4.5% in orthopaedic surgery, 9.7% and 4.4% in neurology, and 10.1% and 12.2% in psychiatry departments, respectively. Mean duration of medication was 1.13 months for non-BZDs, 1.15 months for BZDs, 1.29 months for the ORA and 1.83 months for the MRA. Overall, 5.3% (95% confidence interval 5.2–5.4) of patients were prescribed a second hypnotic drug; of these, 8.4% (95% confidence interval 8.0–8.9) were prescribed at least three hypnotic drugs within a year. Patients who were prescribed three or more hypnotic drugs received higher doses of the first drug than patients who received fewer hypnotic drugs. Conclusions Benzodiazepine receptor agonists were the most common hypnotic drugs prescribed as the first drug to patients in Japan. Further education and awareness may be needed on the risk of complications and adverse events associated with these therapies. The duration of BZD receptor agonist use was shorter than for the MRA and ORA, in accordance with prescribing guidelines. Long-term use and co-prescribing of hypnotic drugs were also uncommon. Key Points The side effects of prolonged benzodiazepine receptor agonist use are more common and/or severe in older adults who take multiple hypnotic drugs concomitantly. This study revealed that benzodiazepine receptor agonists are the most commonly prescribed first-line treatments and are mostly prescribed in the inpatient setting in hospital departments such as internal medicine, general surgery, orthopaedic surgery and urology. A melatonin receptor agonist and an orexin receptor antagonist were commonly prescribed to patients in an outpatient setting in internal medicine, psychiatry and neurology departments

Patterns of hypnotic prescribing for residual insomnia and recurrence of major depressive disorder: a retrospective cohort study using a Japanese health insurance claims database

Background: Major depressive disorder (MDD) is highly prevalent in Japan and frequently accompanied by insomnia that may persist even with MDD remission. Hypnotics are used for the pharmacological treatment of insomnia, but their influence on MDD recurrence or residual insomnia following MDD remission is unclear. This retrospective, longitudinal, cohort study utilized a large Japanese health insurance claims database to investigate patterns of hypnotic prescriptions among patients with MDD, and the influence of hypnotic prescription pattern on MDD recurrence. Methods: Eligible patients (20–56 years) were those registered in the Japan Medical Data Center database between 1 January 2005 and 31 December 2018, and prescribed antidepressant and hypnotic therapy after being diagnosed with MDD. Patients who had ceased antidepressant therapy for > 180 days were followed for 1 year to evaluate depression recurrence, as assessed using Kaplan-Meier estimates. Logistic regression modelling was used to analyze the effect of hypnotic prescription pattern on MDD recurrence. Results: Of the 179,174 patients diagnosed with MDD who initiated antidepressant treatment between 1 January 2006 and 30 June 2017, complete prescription information was available for 2946 eligible patients who had been prescribed hypnotics. More patients were prescribed hypnotic monotherapy (70.8%) than combination therapy (29.2%). The most prescribed therapies were benzodiazepine monotherapy (26.2%), non-benzodiazepine monotherapy (28.9%), and combination therapy with two drugs (21.1%). Among patients prescribed multiple hypnotics, concomitant prescriptions for anxiolytics, antipsychotics, mood stabilizers and sedative antidepressants were more common. The 1-year recurrence rate for MDD was approximately 20%, irrespective of hypnotic monoversus combination therapy or class of hypnotic therapy. Being a spouse (odds ratio [OR], 1.44; 95% confidence interval [CI], 1.03–2.02) or other family member (OR, 1.46, 95% CI, 0.99–2.16) of the insured individual, or being prescribed a sedative antidepressant (OR, 1.50, 95% CI, 1.24–1.82) conferred higher odds of MDD recurrence within 1 year of completing antidepressant therapy. Conclusions: Benzodiazepines are the most prescribed hypnotic among Japanese patients with MDD, though combination hypnotic therapy is routinely prescribed. Hypnotic prescription pattern does not appear to influence real-world MDD recurrence, though hypnotics should be appropriately prescribed given class differences in efficacy and safety

IKs Block and Spiral-Wave Reentry

We tested a hypothesis that an enhancement of IKs may play a pivotal role in ventricular proarrhythmia under high sympathetic activity. A 2-dimensional ventricular muscle layer was prepared in rabbit hearts, and action potential signals were analyzed by optical mapping. During constant stimulation, isoproterenol (ISP, 0.1 μM) significantly shortened action potential duration (APD); chromanol 293B (30 μM), a selective IKs-blocker, reversed the APD shortening. VTs induced in the presence of ISP lasted longer than in the control, and this was reversed by 293B. E-4031 (0.1 μM), a selective IKr-blocker, did not cause such reversal. Spiral-wave (SW) reentry with ISP was characterized by more stable rotation around a shorter functional block line (FBL) than in the control. After application of 293B, SW reentry was destabilized, and rotation around a longer FBL with prominent drift reappeared. The APD abbreviation by ISP close to the rotation center was more pronounced than in the periphery, leading to an opposite APD gradient (center < periphery) compared with controls. This effect was also reversed by 293B. In conclusion, β-adrenergic stimulation stabilizes SW reentry most likely though an enhancement of IKs. Blockade of IKs may be a promising therapeutic modality in prevention of ventricular tachyarrhythmias under high sympathetic activity