40 research outputs found

    Different output properties of perisomatic region-targeting interneurons in the basal amygdala

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    Perisomatic region of principal neurons in the cortical regions is innervated by three types of GABAergic interneurons, including parvalbumi n - containing basket cells (PVBCs) and axo - axonic cells (AACs), as well as cholecystokinin and type 1 cannabinoid receptor - expressing basket cells (CCK/CB1BCs). These perisomatic inhibitory cell types can also be found in the basal nucleus of the amygdala, however, their output properties are largely unknown. Here, we performed whole - cell recordings in morphologically identified interneurons in slices prepared from transgenic mice, in which the GABAergic cells could be selectively targeted. By investigating the passive and active membrane properties of interneurons located within the bas al amygdala , w e observed that the three interneuron types had distinct single - cell properties . For instance, the input resistance, spike rate, accommodation in discharge rate , or after - hyperpolarization width at the half maximal amplitude separated the three interneuron types . Furthermore , we performed paired recordings from interneurons and principal neurons to uncover the basic features of unitary inhibitory postsynaptic curr ents (uIPSCs). We found that, although there was no difference in the magnitude of responses measured in the principal neurons , the uIPSCs originated from the distinct interneuron types differed in the rise time, failure rate, latency and short - term dynami cs. Moreover, the asynchronous transmitter release induced by a train of action potentials was typical for the output synapses of CCK/CB1BCs. Our results suggest that , although the three perisomatic inhibitory cell types give rise to uIPSCs with similar ma gnitude, their distinct spiking characteristics may help to accomplish specific function in amygdala operation

    Spi-OPS : Spitzer and CHEOPS confirm the near-polar orbit of MASCARA-1 b and reveal a hint of dayside reflection

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    A.C.C. and T.G.W. acknowledge support from STFC consolidated grant number ST/M001296/1.Context. The light curves of tidally locked hot Jupiters transiting fast-rotating, early-type stars are a rich source of information about both the planet and star, with full-phase coverage enabling a detailed atmospheric characterisation of the planet. Although it is possible to determine the true spin–orbit angle Ψ – a notoriously difficult parameter to measure – from any transit asymmetry resulting from gravity darkening induced by the stellar rotation, the correlations that exist between the transit parameters have led to large disagreements in published values of Ψ for some systems. Aims. We aimed to study these phenomena in the light curves of the ultra-hot Jupiter MASCARA-1 b, which is characteristically similar to well-studied contemporaries such as KELT-9 b and WASP-33 b. Methods. We obtained optical CHaracterising ExOPlanet Satellite (CHEOPS) transit and occultation light curves of MASCARA-1 b, and analysed them jointly with a Spitzer/IRAC 4.5 μm full-phase curve to model the asymmetric transits, occultations, and phase-dependent flux modulation. For the latter, we employed a novel physics-driven approach to jointly fit the phase modulation by generating a single 2D temperature map and integrating it over the two bandpasses as a function of phase to account for the differing planet–star flux contrasts. The reflected light component was modelled using the general ab initio solution for a semi-infinite atmosphere. Results. When fitting the CHEOPS and Spitzer transits together, the degeneracies are greatly diminished and return results consistent with previously published Doppler tomography. Placing priors informed by the tomography achieves even better precision, allowing a determination of Ψ = 72.1−2.4+2.5 deg. From the occultations and phase variations, we derived dayside and nightside temperatures of 3062−68+66 K and 1720 ± 330 K, respectively.Our retrieval suggests that the dayside emission spectrum closely follows that of a blackbody. As the CHEOPS occultation is too deep to be attributed to blackbody flux alone, we could separately derive geometric albedo Ag = 0.171−0.068+0.066 and spherical albedo As = 0.266−0.100+0.097 from the CHEOPS data, and Bond albedoAB = 0.057−0.101+0.083 from the Spitzer phase curve.Although small, the Ag and As indicate that MASCARA-1 b is more reflective than most other ultra-hot Jupiters, where H− absorption is expected to dominate. Conclusions. Where possible, priors informed by Doppler tomography should be used when fitting transits of fast-rotating stars, though multi-colour photometry may also unlock an accurate measurement of Ψ. Our approach to modelling the phase variations at different wavelengths provides a template for how to separate thermal emission from reflected light in spectrally resolved James Webb Space Telescope phase curve data.Publisher PDFPeer reviewe

    Transit timing variations of AU Microscopii b and c

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    Here we report large-amplitude transit timing variations (TTVs) for AU Microcopii b and c as detected in combined TESS (2018, 2020) and CHEOPS (2020, 2021) transit observations. AU Mic is a young planetary system with a debris disk and two transiting warm Neptunes. A TTV on the order of several minutes was previously reported for AU Mic b, which was suggested to be an outcome of mutual perturbations between the planets in the system. In 2021, we observed AU Mic b (five transits) and c (three transits) with the CHEOPS space telescope to follow-up the TTV of AU Mic b and possibly detect a TTV for AU Mic c. When analyzing TESS and CHEOPS 2020a 2021 measurements together, we find that a prominent TTV emerges with a full span of a ¥23 min between the two TTV extrema. Assuming that the period change results from a periodic process a such as mutual perturbationsa we demonstrate that the times of transits in the summer of 2022 are expected to be 30a 85 min later than predicted by the available linear ephemeris. © 2022 ESO
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