Search

A sensitive Breakthrough Listen search for technosignatures towards Proxima Centauri has resulted in a viable narrowband signal. The observational approach, using the Parkes Murriyang telescope, is described here, while the signal of interest is analysed in a companion paper by Sheikh et al.

The activity of somatostatin-expressing inhibitory neurons (SOMs) in the superficial layers of the mouse visual cortex increases with stimulation of the receptive-field surround, thereby contributing to the surround suppression of pyramidal cells.

Two double-sun exoplanets have been discovered by the Kepler spacecraft, establishing a new class of ‘circumbinary’ exoplanets and suggesting that at least several million such systems exist in our Galaxy.

The authors report on a temperate Earth-sized planet orbiting the cool M6 dwarf LP 791-18 with a radius of 1.03 ± 0.04 R_⊕ and an equilibrium temperature of 300–400 K, with the permanent night side plausibly allowing for water condensation.

Stellar data from the Kepler spacecraft are used to infer the existence of a sub-Mercury-sized exoplanet, the smallest yet discovered, in orbit around a Sun-like star.

Multi-instrument detection of a nearby type 1a supernova shows that the exploding star was probably a carbon–oxygen white dwarf star in a binary system with a main-sequence companion.

The transits of two Sun-like stars by small planets in an open star cluster are reported; such a stellar environment is unlike that of most planet-hosting field stars, and suggests that the occurrence of planets is unaffected by the stellar environment in open clusters.

Whereas large planets, such as gas giants, are more likely to form around high-metallicity stars, terrestrial-sized planets are found to form around stars with a wide range of metallicities, indicating that they may be widespread in the disk of the Galaxy.

The giant planet 8 Ursae Minoris b seems to have avoided engulfment by its giant host star through a stellar merger that either affected the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet.

A comprehensive study of the Kepler-138 system reveals the twin nature of Kepler-138 c and d and the presence of a fourth planet. Remarkably, the warm-temperate planet Kepler-138 d is probably composed of 50% volatiles by volume, indicative of a water world, rather than a rocky world, despite its small ~1.5 R_⊕ size.

Layer six in the mouse primary visual cortex is a major mediator of cortical gain modulation and may be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing.

The ‘jGCaMP7’ sensors are four genetically encoded calcium indicators with better sensitivity than state-of-the-art GCaMP6 and specifically improved for applications such as neuropil or wide-field imaging. The sensors are validated in vivo in both flies and mice.

Doppler spectroscopic measurements of the mass of the Earth-sized planet Kepler-78b reveal that its mean density is similar to Earth’s, suggesting a composition of rock and iron.

The pulsation spectra of intermediate-mass stars (so-called δ Scuti stars) have been challenging to analyse, but new observations of 60 such stars reveal remarkably regular sequences of high-frequency pulsation modes.

Radial-velocity measurements of a Galactic B-type star show a dark companion that seems to be a black hole of about 68 solar masses, in a widely spaced binary system.

Analysis of the metallicities of more than 400 stars hosting 600 candidate extrasolar planets shows that the planets can be categorized by size into three populations — terrestrial-like planets, gas dwarf planets with rocky cores and hydrogen–helium envelopes, and ice or gas giant planets — on the basis of host star metallicity.

A state-of-the-art machine-learning method combs a 480-h-long dataset of 820 nearby stars from the SETI Breakthrough Listen project, reducing the number of interesting signals by two orders of magnitude. Further visual inspection identifies eight promising signals of interest from different stars that warrant further observations.

A radio signal detected in the direction of Proxima Centauri in a Breakthrough Listen programme is analysed for signs that it was transmitted by extraterrestrial intelligent life, using a newly developed framework. However, the signal ‘blc1’ is likely to be terrestrial radio-frequency interference.

Direction selectivity emerges de novo in layer 4 neurons of primary visual cortex through the convergence of synaptic inputs from thalamic neurons that respond with distinct time courses to visual stimuli in distinct locations.

Using a combination of optogenetics, single-cell molecular profiling and paired electrophysiological recordings in the mouse visual cortex, Pfeffer and colleagues derived the connectivity matrix of three major classes of interneurons with their post-synaptic GABAergic targets. This study provides a comprehensive overview of the wiring rules of the inhibition of inhibition in the cortex.

A common anatomical feature of the sensory cortex in many species is that neurons with similar features cluster into vertically orientated domains spanning all layers of the cortex. Moreover, neurons in one domain modulate neurons in neighbouring domains through horizontal connections. A combination of techniques has now been used to show that such horizontal projections suppress layers of cortex devoted to processing inputs, but facilitate layers devoted to outputs.

By optogenetically silencing thalamus, the authors show that visual cortex does not sustain a response without thalamus for more than a few tens of milliseconds. This rapid cortical activity decay predicts the temporal dynamics of sensory activity transmission between thalamus and cortex in awake animals, whereas under anesthesia, the fidelity of thalamo-cortical connection is dominated by the effect of synaptic depression.

Using optogenetics to silence the cortex, the authors show that thalamic inputs to layer 4 V1 neurons in anesthetized mice only contribute a third of the total excitation to these cells during presentation of visual stimuli. Moreover, they find that a small offset in the center of ON and OFF receptive subfields accounts for the orientation tuning of thalamic excitation to these cells.

Feedback projections onto neurons of the mouse primary visual cortex generate a second excitatory receptive field that is driven by stimuli outside of the classical feedforward receptive field, with responses mediated by higher visual areas.

A fully formed, Neptune-sized planet is observed orbiting a young star, demonstrating that planets can form in less than 10 million years and may also experience inward migration on these timescales.

The cortex is sensitive to weak stimuli, but also responds to stronger inputs without saturating. In this study, Scanziani and colleagues find some of the circuits that enable neuronal populations to respond to a wide range of input strengths.

Transit timing variations of the four-planet system Kepler-223 are used to compute the long-term stability of the system, which has a chain of resonances; the results suggest that inward planetary migration, rather than in situ assembly, is responsible for the formation of some close-in sub-Neptune systems.

The authors establish a critical role for somatostatin interneurons in visually induced gamma oscillations in the primary visual cortex of mice. Optogenetic manipulations in awake animals, combined with an innovative computational model with multiple interneuron subtypes, provide a mechanism for the synchronization of neural firing across the retinotopic map.

Different amounts of excitation received by different pyramidal cells of primary visual cortex are matched by proportional amounts of inhibition.

Projections from the mouse visual cortex to the brainstem accessory optic system promote the adaptive plasticity of the optokinetic reflex, which stabilizes images on the retina when an animal is moving.

A rodent study using optogenetics to induce long-term potentiation and long-term depression provides a causal link between synaptic plasticity and memory.