In mammals, including humans, sudden sound or tactile stimuli can momentarily induce the startle reflex. The startle reflex exists throughout the life cycle of mammals. By urgently mobilizing multiple muscle contraction responses in the body, it protects vulnerable parts such as the eyes and back of the neck, and prepares for further defensive responses such as avoidance, escape, etc. . The startle reflex is an important instinctive defensive behavior, but the underlying neural circuits that control the startle reflex remain unclear. Chinese researchers have found that the neural circuit of the cochlear nucleus – the caudal reticular nucleus of the pons – spinal cord motor neurons plays an important role in the startle reflex in mammals. When the startle reflex is evoked by sound, glutamatergic neurons located in the caudal pontine reticular nucleus of the mammalian brainstem are massively activated. Glutamatergic neurons directly receive excitatory projections from the cochlear nucleus and have direct synaptic connections with spinal cord motor neurons, ultimately completing the control of neck and limb muscles.
What is the appetite of baleen whales
Baleen whales are the general term for cetaceans that use comb-like structures to filter food, and are the largest animals that have ever lived on Earth. How much they eat has previously been estimated based on metabolic models or by analyzing the stomach contents of dead whales. In a new study, researchers used drones, echo sounding equipment and sucker tracking devices to track the feeding of 321 whales from 2010 to 2019, spanning the Atlantic, Pacific and Southern Oceans data for seven species, including blue whales, humpback whales and fin whales. It was found that, on average, baleen whales consumed three times as much food as previously estimated. For example, an adult North Pacific blue whale eats an average of 16 tons of krill per day, the equivalent of the weight of a city bus. The new research also supports the so-called krill paradox, in which krill populations have plummeted as their biggest predators disappear. This is because whales forage on the bottom of the sea and defecate on the surface, which circulates nutrients throughout the ocean and promotes the proliferation of plankton that form the basis of the food chain, and fish and shrimp also increase. At the same time, the oceans can also absorb more carbon dioxide from the atmosphere.
Atmospheric microplastics may affect the global climate
Microplastics are becoming a widespread pollutant in the global atmosphere, their small size and low density allow them to travel around the planet by wind. The harm of microplastics is “micro”, the small diameter of the particles means a higher specific surface area and a stronger ability to adsorb pollutants. Atmospheric aerosols are known to heat or cool Earth’s climate by absorbing and scattering radiation. So, could atmospheric microplastics have the same effect? New Zealand researchers calculated the radiation effect of common atmospheric microplastics through climate modeling, and found that atmospheric microplastics may have a small cooling effect on the climate by reflecting sunlight radiation; as microplastics continue to accumulate in the earth’s environment, it may be possible in the future. will exhibit a stronger climate effect. This is the first calculation of the direct global climate impact of atmospheric microplastics. Microplastics are everywhere, even in remote arctic regions, and London, UK, has one of the highest concentrations of microplastics in the atmosphere measured so far. Synthetic fibers are the largest source of microplastics (92.3%) and are mostly composed of polyester.
